Merge pull request #4215 from dhalbert/secondary-cdc

Second USB CDC (serial) channel

53 files changed, 1796 insertions, 683 deletions

diff --git a/main.c b/main.c
index 7bfa565df..7df6e293a 100755
--- a/main.c
+++ b/main.c
@@ -69,6 +69,19 @@
 #include "shared-bindings/alarm/__init__.h"
 #endif
 
+#if CIRCUITPY_BLEIO
+#include "shared-bindings/_bleio/__init__.h"
+#include "supervisor/shared/bluetooth.h"
+#endif
+
+#if CIRCUITPY_BOARD
+#include "shared-module/board/__init__.h"
+#endif
+
+#if CIRCUITPY_CANIO
+#include "common-hal/canio/CAN.h"
+#endif
+
 #if CIRCUITPY_DISPLAYIO
 #include "shared-module/displayio/__init__.h"
 #endif
@@ -81,17 +94,8 @@
 #include "shared-module/network/__init__.h"
 #endif
 
-#if CIRCUITPY_BOARD
-#include "shared-module/board/__init__.h"
-#endif
-
-#if CIRCUITPY_BLEIO
-#include "shared-bindings/_bleio/__init__.h"
-#include "supervisor/shared/bluetooth.h"
-#endif
-
-#if CIRCUITPY_CANIO
-#include "common-hal/canio/CAN.h"
+#if CIRCUITPY_USB_CDC
+#include "shared-module/usb_cdc/__init__.h"
 #endif
 
 #if CIRCUITPY_WIFI
diff --git a/ports/atmel-samd/Makefile b/ports/atmel-samd/Makefile
index 58c1c0d60..48724af0c 100644
--- a/ports/atmel-samd/Makefile
+++ b/ports/atmel-samd/Makefile
@@ -122,7 +122,7 @@ CFLAGS += -ftree-vrp
 $(echo PERIPHERALS_CHIP_FAMILY=$(PERIPHERALS_CHIP_FAMILY))
 #Debugging/Optimization
 ifeq ($(DEBUG), 1)
-  CFLAGS += -ggdb3 -Og
+  CFLAGS += -ggdb3 -Og -Os
   # You may want to disable -flto if it interferes with debugging.
   CFLAGS += -flto -flto-partition=none
   # You may want to enable these flags to make setting breakpoints easier.
diff --git a/ports/atmel-samd/boards/sparkfun_samd21_mini/mpconfigboard.mk b/ports/atmel-samd/boards/sparkfun_samd21_mini/mpconfigboard.mk
index 9460d0009..aef38661b 100644
--- a/ports/atmel-samd/boards/sparkfun_samd21_mini/mpconfigboard.mk
+++ b/ports/atmel-samd/boards/sparkfun_samd21_mini/mpconfigboard.mk
@@ -11,3 +11,4 @@ LONGINT_IMPL = NONE
 CIRCUITPY_FULL_BUILD = 0
 
 SUPEROPT_GC = 0
+SUPEROPT_VM = 0
diff --git a/ports/atmel-samd/common-hal/supervisor/Runtime.c b/ports/atmel-samd/common-hal/supervisor/Runtime.c
index 6be38f216..974f26cec 100755
--- a/ports/atmel-samd/common-hal/supervisor/Runtime.c
+++ b/ports/atmel-samd/common-hal/supervisor/Runtime.c
@@ -28,10 +28,10 @@
 #include "shared-bindings/supervisor/Runtime.h"
 #include "supervisor/serial.h"
 
-bool common_hal_get_serial_connected(void) {
+bool common_hal_supervisor_runtime_get_serial_connected(void) {
     return (bool) serial_connected();
 }
 
-bool common_hal_get_serial_bytes_available(void) {
+bool common_hal_supervisor_runtime_get_serial_bytes_available(void) {
     return (bool) serial_bytes_available();
 }
diff --git a/ports/atmel-samd/mpconfigport.mk b/ports/atmel-samd/mpconfigport.mk
index fb9cdf2e6..e47acfb36 100644
--- a/ports/atmel-samd/mpconfigport.mk
+++ b/ports/atmel-samd/mpconfigport.mk
@@ -18,7 +18,16 @@ ifeq ($(LONGINT_IMPL),LONGLONG)
 MPY_TOOL_LONGINT_IMPL = -mlongint-impl=longlong
 endif
 
+INTERNAL_LIBM = 1
+
+USB_SERIAL_NUMBER_LENGTH = 32
+
+# Number of USB endpoint pairs.
+USB_NUM_EP = 8
+
+######################################################################
 # Put samd21-only choices here.
+
 ifeq ($(CHIP_FAMILY),samd21)
 
 # The ?='s allow overriding in mpconfigboard.mk.
@@ -40,7 +49,9 @@ CIRCUITPY_SDCARDIO ?= 0
 CIRCUITPY_FRAMEBUFFERIO ?= 0
 
 # SAMD21 needs separate endpoint pairs for MSC BULK IN and BULK OUT, otherwise it's erratic.
+# Because of that, there aren't enough endpoints for a secondary CDC serial connection.
 USB_MSC_EP_NUM_OUT = 1
+CIRCUITPY_USB_CDC = 0
 
 CIRCUITPY_ULAB = 0
 
@@ -55,9 +66,13 @@ CIRCUITPY_TERMINALIO = 0
 endif
 
 endif # samd21
+######################################################################
 
+######################################################################
 # Put samd51-only choices here.
+
 ifeq ($(CHIP_FAMILY),samd51)
+
 # No native touchio on SAMD51.
 CIRCUITPY_TOUCHIO_USE_NATIVE = 0
 
@@ -70,9 +85,4 @@ CIRCUITPY_RGBMATRIX ?= $(CIRCUITPY_FULL_BUILD)
 CIRCUITPY_FRAMEBUFFERIO ?= $(CIRCUITPY_FULL_BUILD)
 
 endif # samd51
-
-INTERNAL_LIBM = 1
-
-USB_SERIAL_NUMBER_LENGTH = 32
-
-USB_NUM_EP = 8
+######################################################################
diff --git a/ports/cxd56/common-hal/supervisor/Runtime.c b/ports/cxd56/common-hal/supervisor/Runtime.c
index a0d9e70ab..eeeb1430f 100755
--- a/ports/cxd56/common-hal/supervisor/Runtime.c
+++ b/ports/cxd56/common-hal/supervisor/Runtime.c
@@ -27,10 +27,10 @@
 #include "shared-bindings/supervisor/Runtime.h"
 #include "supervisor/serial.h"
 
-bool common_hal_get_serial_connected(void) {
+bool common_hal_supervisor_runtime_get_serial_connected(void) {
     return (bool) serial_connected();
 }
 
-bool common_hal_get_serial_bytes_available(void) {
+bool common_hal_supervisor_runtime_get_serial_bytes_available(void) {
     return (bool) serial_bytes_available();
 }
diff --git a/ports/cxd56/mpconfigport.mk b/ports/cxd56/mpconfigport.mk
index e1ffc79d0..33a993ad9 100644
--- a/ports/cxd56/mpconfigport.mk
+++ b/ports/cxd56/mpconfigport.mk
@@ -7,6 +7,9 @@ USB_CDC_EP_NUM_DATA_IN = 1
 USB_MSC_EP_NUM_OUT = 5
 USB_MSC_EP_NUM_IN = 4
 
+# Number of USB endpoint pairs.
+USB_NUM_EP = 6
+
 MPY_TOOL_LONGINT_IMPL = -mlongint-impl=mpz
 
 CIRCUITPY_AUDIOBUSIO = 0
diff --git a/ports/esp32s2/boards/lilygo_ttgo_t8_s2_st7789/mpconfigboard.mk b/ports/esp32s2/boards/lilygo_ttgo_t8_s2_st7789/mpconfigboard.mk
index 38a7ed1fb..79b45fd92 100644
--- a/ports/esp32s2/boards/lilygo_ttgo_t8_s2_st7789/mpconfigboard.mk
+++ b/ports/esp32s2/boards/lilygo_ttgo_t8_s2_st7789/mpconfigboard.mk
@@ -2,7 +2,6 @@ USB_VID = 0x303a
 USB_PID = 0x8007
 USB_PRODUCT = "TTGO T8 ESP32-S2"
 USB_MANUFACTURER = "LILYGO"
-USB_DEVICES = "CDC,MSC,HID"
 
 INTERNAL_FLASH_FILESYSTEM = 1
 LONGINT_IMPL = MPZ
diff --git a/ports/esp32s2/boards/microdev_micro_s2/mpconfigboard.mk b/ports/esp32s2/boards/microdev_micro_s2/mpconfigboard.mk
index 515617095..783e7ad4c 100644
--- a/ports/esp32s2/boards/microdev_micro_s2/mpconfigboard.mk
+++ b/ports/esp32s2/boards/microdev_micro_s2/mpconfigboard.mk
@@ -2,7 +2,6 @@ USB_VID = 0x239A
 USB_PID = 0x80C6
 USB_PRODUCT = "microS2"
 USB_MANUFACTURER = "microDev"
-USB_DEVICES = "CDC,MSC,HID"
 
 INTERNAL_FLASH_FILESYSTEM = 1
 LONGINT_IMPL = MPZ
diff --git a/ports/esp32s2/boards/unexpectedmaker_feathers2/mpconfigboard.mk b/ports/esp32s2/boards/unexpectedmaker_feathers2/mpconfigboard.mk
index 9857c0761..d045cc214 100644
--- a/ports/esp32s2/boards/unexpectedmaker_feathers2/mpconfigboard.mk
+++ b/ports/esp32s2/boards/unexpectedmaker_feathers2/mpconfigboard.mk
@@ -2,7 +2,6 @@ USB_VID = 0x239A
 USB_PID = 0x80AC
 USB_PRODUCT = "FeatherS2"
 USB_MANUFACTURER = "UnexpectedMaker"
-USB_DEVICES = "CDC,MSC,HID"
 
 INTERNAL_FLASH_FILESYSTEM = 1
 LONGINT_IMPL = MPZ
diff --git a/ports/esp32s2/boards/unexpectedmaker_feathers2_prerelease/mpconfigboard.mk b/ports/esp32s2/boards/unexpectedmaker_feathers2_prerelease/mpconfigboard.mk
index 9857c0761..d045cc214 100644
--- a/ports/esp32s2/boards/unexpectedmaker_feathers2_prerelease/mpconfigboard.mk
+++ b/ports/esp32s2/boards/unexpectedmaker_feathers2_prerelease/mpconfigboard.mk
@@ -2,7 +2,6 @@ USB_VID = 0x239A
 USB_PID = 0x80AC
 USB_PRODUCT = "FeatherS2"
 USB_MANUFACTURER = "UnexpectedMaker"
-USB_DEVICES = "CDC,MSC,HID"
 
 INTERNAL_FLASH_FILESYSTEM = 1
 LONGINT_IMPL = MPZ
diff --git a/ports/esp32s2/common-hal/supervisor/Runtime.c b/ports/esp32s2/common-hal/supervisor/Runtime.c
index ea663f897..974f26cec 100644
--- a/ports/esp32s2/common-hal/supervisor/Runtime.c
+++ b/ports/esp32s2/common-hal/supervisor/Runtime.c
@@ -28,10 +28,10 @@
 #include "shared-bindings/supervisor/Runtime.h"
 #include "supervisor/serial.h"
 
-bool common_hal_get_serial_connected(void) {
+bool common_hal_supervisor_runtime_get_serial_connected(void) {
     return (bool) serial_connected();
 }
 
-bool common_hal_get_serial_bytes_available(void) {
-  return (bool) serial_bytes_available();
+bool common_hal_supervisor_runtime_get_serial_bytes_available(void) {
+    return (bool) serial_bytes_available();
 }
diff --git a/ports/esp32s2/mpconfigport.mk b/ports/esp32s2/mpconfigport.mk
index b273c02ee..5073d8812 100644
--- a/ports/esp32s2/mpconfigport.mk
+++ b/ports/esp32s2/mpconfigport.mk
@@ -28,6 +28,8 @@ CIRCUITPY_FREQUENCYIO = 1
 CIRCUITPY_I2CPERIPHERAL = 0
 CIRCUITPY_ROTARYIO = 1
 CIRCUITPY_NVM = 1
+CIRCUITPY_PS2IO ?= 1
+CIRCUITPY_TOUCHIO_USE_NATIVE ?= 1
 # We don't have enough endpoints to include MIDI.
 CIRCUITPY_USB_MIDI ?= 0
 CIRCUITPY_USB_HID ?= 1
@@ -35,14 +37,9 @@ CIRCUITPY_USB_HID ?= 1
 CIRCUITPY_USB_VENDOR ?= 0
 CIRCUITPY_WIFI = 1
 CIRCUITPY_WATCHDOG ?= 1
-CIRCUITPY_ESPIDF = 1
-
-ifndef CIRCUITPY_PS2IO
-CIRCUITPY_PS2IO = 1
-endif
 
-ifndef CIRCUITPY_TOUCHIO_USE_NATIVE
-CIRCUITPY_TOUCHIO_USE_NATIVE = 1
-endif
+CIRCUITPY_ESPIDF = 1
 
 CIRCUITPY_MODULE ?= none
+
+USB_NUM_EP = 5
diff --git a/ports/litex/common-hal/supervisor/Runtime.c b/ports/litex/common-hal/supervisor/Runtime.c
index ea663f897..974f26cec 100644
--- a/ports/litex/common-hal/supervisor/Runtime.c
+++ b/ports/litex/common-hal/supervisor/Runtime.c
@@ -28,10 +28,10 @@
 #include "shared-bindings/supervisor/Runtime.h"
 #include "supervisor/serial.h"
 
-bool common_hal_get_serial_connected(void) {
+bool common_hal_supervisor_runtime_get_serial_connected(void) {
     return (bool) serial_connected();
 }
 
-bool common_hal_get_serial_bytes_available(void) {
-  return (bool) serial_bytes_available();
+bool common_hal_supervisor_runtime_get_serial_bytes_available(void) {
+    return (bool) serial_bytes_available();
 }
diff --git a/ports/litex/mpconfigport.mk b/ports/litex/mpconfigport.mk
index 003fb5c2c..af6a94e64 100644
--- a/ports/litex/mpconfigport.mk
+++ b/ports/litex/mpconfigport.mk
@@ -6,6 +6,9 @@ MPY_TOOL_LONGINT_IMPL = -mlongint-impl=mpz
 # Internal math library is substantially smaller than toolchain one
 INTERNAL_LIBM = 1
 
+# Number of USB endpoint pairs.
+USB_NUM_EP = 16
+
 # Chip supplied serial number, in bytes
 USB_SERIAL_NUMBER_LENGTH = 30
 
diff --git a/ports/mimxrt10xx/common-hal/supervisor/Runtime.c b/ports/mimxrt10xx/common-hal/supervisor/Runtime.c
index 6be38f216..974f26cec 100755
--- a/ports/mimxrt10xx/common-hal/supervisor/Runtime.c
+++ b/ports/mimxrt10xx/common-hal/supervisor/Runtime.c
@@ -28,10 +28,10 @@
 #include "shared-bindings/supervisor/Runtime.h"
 #include "supervisor/serial.h"
 
-bool common_hal_get_serial_connected(void) {
+bool common_hal_supervisor_runtime_get_serial_connected(void) {
     return (bool) serial_connected();
 }
 
-bool common_hal_get_serial_bytes_available(void) {
+bool common_hal_supervisor_runtime_get_serial_bytes_available(void) {
     return (bool) serial_bytes_available();
 }
diff --git a/ports/mimxrt10xx/mpconfigport.mk b/ports/mimxrt10xx/mpconfigport.mk
index b4cc9586a..de594b14b 100644
--- a/ports/mimxrt10xx/mpconfigport.mk
+++ b/ports/mimxrt10xx/mpconfigport.mk
@@ -17,6 +17,9 @@ INTERNAL_LIBM = 1
 USB_SERIAL_NUMBER_LENGTH = 32
 USB_HIGHSPEED = 1
 
+# Number of USB endpoint pairs.
+USB_NUM_EP = 8
+
 INTERNAL_FLASH_FILESYSTEM = 1
 
 CIRCUITPY_AUDIOIO = 0
diff --git a/ports/nrf/bluetooth/ble_uart.c b/ports/nrf/bluetooth/ble_uart.c
index 1e7a319bd..1b87b82d1 100644
--- a/ports/nrf/bluetooth/ble_uart.c
+++ b/ports/nrf/bluetooth/ble_uart.c
@@ -40,7 +40,7 @@
 #include "shared-bindings/_bleio/Service.h"
 #include "shared-bindings/_bleio/UUID.h"
 
-#if CIRCUITPY_SERIAL_BLE
+#if CIRCUITPY_REPL_BLE
 
 static const char default_name[] = "CP-REPL"; // max 8 chars or uuid won't fit in adv data
 static const char NUS_UUID[] = "6e400001-b5a3-f393-e0a9-e50e24dcca9e";
@@ -190,4 +190,4 @@ void mp_hal_stdout_tx_strn(const char *str, size_t len) {
     }
 }
 
-#endif // CIRCUITPY_SERIAL_BLE
+#endif // CIRCUITPY_REPL_BLE
diff --git a/ports/nrf/boards/pca10100/mpconfigboard.mk b/ports/nrf/boards/pca10100/mpconfigboard.mk
index c8cba2877..fbb9987c2 100644
--- a/ports/nrf/boards/pca10100/mpconfigboard.mk
+++ b/ports/nrf/boards/pca10100/mpconfigboard.mk
@@ -29,6 +29,7 @@ CIRCUITPY_BUSDEVICE = 0
 MICROPY_PY_ASYNC_AWAIT = 0
 
 SUPEROPT_GC = 0
+SUPEROPT_VM = 0
 
 # Override optimization to keep binary small
 OPTIMIZATION_FLAGS = -Os
diff --git a/ports/nrf/boards/simmel/mpconfigboard.mk b/ports/nrf/boards/simmel/mpconfigboard.mk
index 6bc05a7f0..52743d340 100644
--- a/ports/nrf/boards/simmel/mpconfigboard.mk
+++ b/ports/nrf/boards/simmel/mpconfigboard.mk
@@ -3,8 +3,6 @@ USB_PID = 0xc051
 USB_PRODUCT = "Simmel"
 USB_MANUFACTURER = "Betrusted"
 
-CIRCUITPY_DEVICES="CDC,MSC,HID"
-
 MCU_CHIP = nrf52833
 
 # SPI_FLASH_FILESYSTEM = 1
@@ -31,6 +29,7 @@ CIRCUITPY_RTC = 1
 CIRCUITPY_SDCARDIO = 0
 CIRCUITPY_TOUCHIO = 0
 CIRCUITPY_ULAB = 0
+CIRCUITPY_USB_CDC = 0
 CIRCUITPY_USB_MIDI = 0
 CIRCUITPY_WATCHDOG = 1
 
diff --git a/ports/nrf/common-hal/supervisor/Runtime.c b/ports/nrf/common-hal/supervisor/Runtime.c
index ea663f897..a24e86cdf 100755
--- a/ports/nrf/common-hal/supervisor/Runtime.c
+++ b/ports/nrf/common-hal/supervisor/Runtime.c
@@ -28,10 +28,10 @@
 #include "shared-bindings/supervisor/Runtime.h"
 #include "supervisor/serial.h"
 
-bool common_hal_get_serial_connected(void) {
+bool common_hal_supervisor_runtime_get_serial_connected(void) {
     return (bool) serial_connected();
 }
 
-bool common_hal_get_serial_bytes_available(void) {
+bool common_hal_supervisor_runtime_get_serial_bytes_available(void) {
   return (bool) serial_bytes_available();
 }
diff --git a/ports/nrf/mpconfigport.mk b/ports/nrf/mpconfigport.mk
index 9560064fb..83924ff79 100644
--- a/ports/nrf/mpconfigport.mk
+++ b/ports/nrf/mpconfigport.mk
@@ -11,6 +11,9 @@ INTERNAL_LIBM = 1
 
 USB_SERIAL_NUMBER_LENGTH = 16
 
+# Number of USB endpoint pairs.
+USB_NUM_EP = 8
+
 # All nRF ports have longints.
 LONGINT_IMPL = MPZ
 
diff --git a/ports/nrf/supervisor/serial.c b/ports/nrf/supervisor/serial.c
index b19e9267c..2c2c0116f 100644
--- a/ports/nrf/supervisor/serial.c
+++ b/ports/nrf/supervisor/serial.c
@@ -28,15 +28,15 @@
 
 #include "supervisor/serial.h"
 
-#if CIRCUITPY_SERIAL_BLE
+#if CIRCUITPY_REPL_BLE
 #include "ble_uart.h"
-#elif CIRCUITPY_SERIAL_UART
+#elif CIRCUITPY_REPL_UART
 #include <string.h>
 #include "nrf_gpio.h"
 #include "nrfx_uarte.h"
 #endif
 
-#if CIRCUITPY_SERIAL_BLE
+#if CIRCUITPY_REPL_BLE
 
 void serial_init(void) {
     ble_uart_init();
@@ -58,7 +58,7 @@ void serial_write(const char *text) {
     ble_uart_stdout_tx_str(text);
 }
 
-#elif CIRCUITPY_SERIAL_UART
+#elif CIRCUITPY_REPL_UART
 
 uint8_t serial_received_char;
 nrfx_uarte_t serial_instance = NRFX_UARTE_INSTANCE(0);
@@ -124,4 +124,4 @@ void serial_write_substring(const char *text, uint32_t len) {
     }
 }
 
-#endif  // CIRCUITPY_SERIAL_UART
+#endif  // CIRCUITPY_REPL_UART
diff --git a/ports/raspberrypi/common-hal/supervisor/Runtime.c b/ports/raspberrypi/common-hal/supervisor/Runtime.c
index 6be38f216..974f26cec 100755
--- a/ports/raspberrypi/common-hal/supervisor/Runtime.c
+++ b/ports/raspberrypi/common-hal/supervisor/Runtime.c
@@ -28,10 +28,10 @@
 #include "shared-bindings/supervisor/Runtime.h"
 #include "supervisor/serial.h"
 
-bool common_hal_get_serial_connected(void) {
+bool common_hal_supervisor_runtime_get_serial_connected(void) {
     return (bool) serial_connected();
 }
 
-bool common_hal_get_serial_bytes_available(void) {
+bool common_hal_supervisor_runtime_get_serial_bytes_available(void) {
     return (bool) serial_bytes_available();
 }
diff --git a/ports/raspberrypi/mpconfigport.mk b/ports/raspberrypi/mpconfigport.mk
index b93e4dcc7..ab85c59f9 100644
--- a/ports/raspberrypi/mpconfigport.mk
+++ b/ports/raspberrypi/mpconfigport.mk
@@ -50,4 +50,5 @@ INTERNAL_LIBM = 1
 
 USB_SERIAL_NUMBER_LENGTH = 16
 
+# Number of USB endpoint pairs.
 USB_NUM_EP = 8
diff --git a/ports/stm/boards/stm32f412zg_discovery/mpconfigboard.mk b/ports/stm/boards/stm32f412zg_discovery/mpconfigboard.mk
index c99eb1a00..28874f9c6 100644
--- a/ports/stm/boards/stm32f412zg_discovery/mpconfigboard.mk
+++ b/ports/stm/boards/stm32f412zg_discovery/mpconfigboard.mk
@@ -16,5 +16,3 @@ MCU_PACKAGE = LQFP144
 
 LD_COMMON = boards/common_default.ld
 LD_FILE = boards/STM32F412_fs.ld
-
-CIRCUITPY_USB_HID = 1
diff --git a/ports/stm/boards/thunderpack_v12/mpconfigboard.mk b/ports/stm/boards/thunderpack_v12/mpconfigboard.mk
index a2e1da101..4436f04b7 100644
--- a/ports/stm/boards/thunderpack_v12/mpconfigboard.mk
+++ b/ports/stm/boards/thunderpack_v12/mpconfigboard.mk
@@ -2,7 +2,9 @@ USB_VID = 0x239A
 USB_PID = 0x8071
 USB_PRODUCT = "Thunderpack STM32F411"
 USB_MANUFACTURER = "Jeremy Gillick"
-USB_DEVICES = "CDC,MSC"
+
+# Turn off HID devices
+CIRCUITPY_USB_HID = 0
 
 LONGINT_IMPL = NONE
 
diff --git a/ports/stm/common-hal/supervisor/Runtime.c b/ports/stm/common-hal/supervisor/Runtime.c
index ea663f897..974f26cec 100755
--- a/ports/stm/common-hal/supervisor/Runtime.c
+++ b/ports/stm/common-hal/supervisor/Runtime.c
@@ -28,10 +28,10 @@
 #include "shared-bindings/supervisor/Runtime.h"
 #include "supervisor/serial.h"
 
-bool common_hal_get_serial_connected(void) {
+bool common_hal_supervisor_runtime_get_serial_connected(void) {
     return (bool) serial_connected();
 }
 
-bool common_hal_get_serial_bytes_available(void) {
-  return (bool) serial_bytes_available();
+bool common_hal_supervisor_runtime_get_serial_bytes_available(void) {
+    return (bool) serial_bytes_available();
 }
diff --git a/ports/stm/mpconfigport.mk b/ports/stm/mpconfigport.mk
index bcecaa517..fe257fc50 100644
--- a/ports/stm/mpconfigport.mk
+++ b/ports/stm/mpconfigport.mk
@@ -8,6 +8,7 @@ ifeq ($(MCU_VARIANT),STM32F405xx)
 	CIRCUITPY_FRAMEBUFFERIO ?= 1
 	CIRCUITPY_RGBMATRIX ?= 1
 	CIRCUITPY_SDIOIO ?= 1
+	# Number of USB endpoint pairs.
 	USB_NUM_EP = 4
 endif
 
@@ -23,6 +24,8 @@ ifeq ($(MCU_SERIES),F4)
 	CIRCUITPY_RTC ?= 0
 	CIRCUITPY_USB_MIDI ?= 0
 	CIRCUITPY_USB_HID ?= 0
+
+	USB_NUM_EP = 4
 endif
 
 ifeq ($(MCU_SERIES),H7)
@@ -40,6 +43,8 @@ ifeq ($(MCU_SERIES),H7)
 	CIRCUITPY_RTC ?= 0
 	CIRCUITPY_USB_HID ?= 0
 	CIRCUITPY_USB_MIDI ?= 0
+
+	USB_NUM_EP = 9
 endif
 
 ifeq ($(MCU_SERIES),F7)
@@ -56,4 +61,6 @@ ifeq ($(MCU_SERIES),F7)
 	CIRCUITPY_RTC ?= 0
 	CIRCUITPY_USB_HID ?= 0
 	CIRCUITPY_USB_MIDI ?= 0
+
+	USB_NUM_EP = 6
 endif
diff --git a/py/circuitpy_defns.mk b/py/circuitpy_defns.mk
index 47870ede1..943c99f93 100644
--- a/py/circuitpy_defns.mk
+++ b/py/circuitpy_defns.mk
@@ -132,9 +132,6 @@ endif
 ifeq ($(CIRCUITPY_AUDIOMP3),1)
 SRC_PATTERNS += audiomp3/%
 endif
-ifeq ($(CIRCUITPY_BITOPS),1)
-SRC_PATTERNS += bitops/%
-endif
 ifeq ($(CIRCUITPY_BITBANGIO),1)
 SRC_PATTERNS += bitbangio/%
 endif
@@ -142,6 +139,9 @@ endif
 ifeq ($(CIRCUITPY_BITBANG_APA102),1)
 SRC_PATTERNS += bitbangio/SPI%
 endif
+ifeq ($(CIRCUITPY_BITOPS),1)
+SRC_PATTERNS += bitops/%
+endif
 ifeq ($(CIRCUITPY_BLEIO),1)
 SRC_PATTERNS += _bleio/%
 endif
@@ -289,6 +289,9 @@ endif
 ifeq ($(CIRCUITPY_UHEAP),1)
 SRC_PATTERNS += uheap/%
 endif
+ifeq ($(CIRCUITPY_USB_CDC),1)
+SRC_PATTERNS += usb_cdc/%
+endif
 ifeq ($(CIRCUITPY_USB_HID),1)
 SRC_PATTERNS += usb_hid/%
 endif
diff --git a/py/circuitpy_mpconfig.h b/py/circuitpy_mpconfig.h
index d72146c42..cbe668289 100644
--- a/py/circuitpy_mpconfig.h
+++ b/py/circuitpy_mpconfig.h
@@ -299,6 +299,13 @@ extern const struct _mp_obj_module_t audiopwmio_module;
 #define BINASCII_MODULE
 #endif
 
+#if CIRCUITPY_BITBANGIO
+#define BITBANGIO_MODULE       { MP_OBJ_NEW_QSTR(MP_QSTR_bitbangio), (mp_obj_t)&bitbangio_module },
+extern const struct _mp_obj_module_t bitbangio_module;
+#else
+#define BITBANGIO_MODULE
+#endif
+
 #if CIRCUITPY_BITOPS
 extern const struct _mp_obj_module_t bitops_module;
 #define BITOPS_MODULE        { MP_OBJ_NEW_QSTR(MP_QSTR_bitops),(mp_obj_t)&bitops_module },
@@ -307,13 +314,6 @@ extern const struct _mp_obj_module_t bitops_module;
 #endif
 
 
-#if CIRCUITPY_BITBANGIO
-#define BITBANGIO_MODULE       { MP_OBJ_NEW_QSTR(MP_QSTR_bitbangio), (mp_obj_t)&bitbangio_module },
-extern const struct _mp_obj_module_t bitbangio_module;
-#else
-#define BITBANGIO_MODULE
-#endif
-
 #if CIRCUITPY_BLEIO
 #define BLEIO_MODULE           { MP_OBJ_NEW_QSTR(MP_QSTR__bleio), (mp_obj_t)&bleio_module },
 extern const struct _mp_obj_module_t bleio_module;
@@ -744,6 +744,13 @@ extern const struct _mp_obj_module_t uheap_module;
 #define UHEAP_MODULE
 #endif
 
+#if CIRCUITPY_USB_CDC
+extern const struct _mp_obj_module_t usb_cdc_module;
+#define USB_CDC_MODULE         { MP_OBJ_NEW_QSTR(MP_QSTR_usb_cdc),(mp_obj_t)&usb_cdc_module },
+#else
+#define USB_CDC_MODULE
+#endif
+
 #if CIRCUITPY_USB_HID
 extern const struct _mp_obj_module_t usb_hid_module;
 #define USB_HID_MODULE         { MP_OBJ_NEW_QSTR(MP_QSTR_usb_hid),(mp_obj_t)&usb_hid_module },
@@ -827,8 +834,8 @@ extern const struct _mp_obj_module_t msgpack_module;
     AUDIOMP3_MODULE \
     AUDIOPWMIO_MODULE \
     BINASCII_MODULE \
-    BITOPS_MODULE \
     BITBANGIO_MODULE \
+    BITOPS_MODULE \
     BLEIO_MODULE \
     BOARD_MODULE \
     BUSDEVICE_MODULE \
@@ -884,6 +891,7 @@ extern const struct _mp_obj_module_t msgpack_module;
     SUPERVISOR_MODULE \
     TOUCHIO_MODULE \
     UHEAP_MODULE \
+    USB_CDC_MODULE \
     USB_HID_MODULE \
     USB_MIDI_MODULE \
     USTACK_MODULE \
diff --git a/py/circuitpy_mpconfig.mk b/py/circuitpy_mpconfig.mk
index 6244ed136..9d8e53ea7 100644
--- a/py/circuitpy_mpconfig.mk
+++ b/py/circuitpy_mpconfig.mk
@@ -89,12 +89,15 @@ CFLAGS += -DCIRCUITPY_AUDIOMP3=$(CIRCUITPY_AUDIOMP3)
 CIRCUITPY_BINASCII ?= $(CIRCUITPY_FULL_BUILD)
 CFLAGS += -DCIRCUITPY_BINASCII=$(CIRCUITPY_BINASCII)
 
-CIRCUITPY_BITOPS ?= 0
-CFLAGS += -DCIRCUITPY_BITOPS=$(CIRCUITPY_BITOPS)
+CIRCUITPY_BITBANG_APA102 ?= 0
+CFLAGS += -DCIRCUITPY_BITBANG_APA102=$(CIRCUITPY_BITBANG_APA102)
 
 CIRCUITPY_BITBANGIO ?= $(CIRCUITPY_FULL_BUILD)
 CFLAGS += -DCIRCUITPY_BITBANGIO=$(CIRCUITPY_BITBANGIO)
 
+CIRCUITPY_BITOPS ?= 0
+CFLAGS += -DCIRCUITPY_BITOPS=$(CIRCUITPY_BITOPS)
+
 # _bleio can be supported on most any board via HCI
 CIRCUITPY_BLEIO_HCI ?= $(CIRCUITPY_FULL_BUILD)
 CFLAGS += -DCIRCUITPY_BLEIO_HCI=$(CIRCUITPY_BLEIO_HCI)
@@ -103,6 +106,9 @@ CFLAGS += -DCIRCUITPY_BLEIO_HCI=$(CIRCUITPY_BLEIO_HCI)
 CIRCUITPY_BLEIO ?= $(CIRCUITPY_BLEIO_HCI)
 CFLAGS += -DCIRCUITPY_BLEIO=$(CIRCUITPY_BLEIO)
 
+CIRCUITPY_BLE_FILE_SERVICE ?= 0
+CFLAGS += -DCIRCUITPY_BLE_FILE_SERVICE=$(CIRCUITPY_BLE_FILE_SERVICE)
+
 CIRCUITPY_BOARD ?= 1
 CFLAGS += -DCIRCUITPY_BOARD=$(CIRCUITPY_BOARD)
 
@@ -130,6 +136,13 @@ CFLAGS += -DCIRCUITPY_COUNTIO=$(CIRCUITPY_COUNTIO)
 CIRCUITPY_DISPLAYIO ?= $(CIRCUITPY_FULL_BUILD)
 CFLAGS += -DCIRCUITPY_DISPLAYIO=$(CIRCUITPY_DISPLAYIO)
 
+CIRCUITPY_DUALBANK ?= 0
+CFLAGS += -DCIRCUITPY_DUALBANK=$(CIRCUITPY_DUALBANK)
+
+# Enabled micropython.native decorator (experimental)
+CIRCUITPY_ENABLE_MPY_NATIVE ?= 0
+CFLAGS += -DCIRCUITPY_ENABLE_MPY_NATIVE=$(CIRCUITPY_ENABLE_MPY_NATIVE)
+
 CIRCUITPY_ERRNO ?= $(CIRCUITPY_FULL_BUILD)
 CFLAGS += -DCIRCUITPY_ERRNO=$(CIRCUITPY_ERRNO)
 
@@ -182,6 +195,9 @@ CFLAGS += -DCIRCUITPY_MEMORYMONITOR=$(CIRCUITPY_MEMORYMONITOR)
 CIRCUITPY_MICROCONTROLLER ?= 1
 CFLAGS += -DCIRCUITPY_MICROCONTROLLER=$(CIRCUITPY_MICROCONTROLLER)
 
+CIRCUITPY_MSGPACK ?= $(CIRCUITPY_FULL_BUILD)
+CFLAGS += -DCIRCUITPY_MSGPACK=$(CIRCUITPY_MSGPACK)
+
 CIRCUITPY_NEOPIXEL_WRITE ?= 1
 CFLAGS += -DCIRCUITPY_NEOPIXEL_WRITE=$(CIRCUITPY_NEOPIXEL_WRITE)
 
@@ -195,8 +211,8 @@ CFLAGS += -DCIRCUITPY_NVM=$(CIRCUITPY_NVM)
 CIRCUITPY_OS ?= 1
 CFLAGS += -DCIRCUITPY_OS=$(CIRCUITPY_OS)
 
-CIRCUITPY_DUALBANK ?= 0
-CFLAGS += -DCIRCUITPY_DUALBANK=$(CIRCUITPY_DUALBANK)
+CIRCUITPY_PEW ?= 0
+CFLAGS += -DCIRCUITPY_PEW=$(CIRCUITPY_PEW)
 
 CIRCUITPY_PIXELBUF ?= $(CIRCUITPY_FULL_BUILD)
 CFLAGS += -DCIRCUITPY_PIXELBUF=$(CIRCUITPY_PIXELBUF)
@@ -219,6 +235,20 @@ CFLAGS += -DCIRCUITPY_RANDOM=$(CIRCUITPY_RANDOM)
 CIRCUITPY_RE ?= $(CIRCUITPY_FULL_BUILD)
 CFLAGS += -DCIRCUITPY_RE=$(CIRCUITPY_RE)
 
+CIRCUITPY_REPL_BLE ?= 0
+CFLAGS += -DCIRCUITPY_REPL_BLE=$(CIRCUITPY_REPL_BLE)
+
+CIRCUITPY_REPL_UART ?= 0
+CFLAGS += -DCIRCUITPY_REPL_UART=$(CIRCUITPY_REPL_UART)
+
+CIRCUITPY_REPL_USB ?= 1
+CFLAGS += -DCIRCUITPY_REPL_USB=$(CIRCUITPY_REPL_USB)
+
+# Should busio.I2C() check for pullups?
+# Some boards in combination with certain peripherals may not want this.
+CIRCUITPY_REQUIRE_I2C_PULLUPS ?= 1
+CFLAGS += -DCIRCUITPY_REQUIRE_I2C_PULLUPS=$(CIRCUITPY_REQUIRE_I2C_PULLUPS)
+
 # CIRCUITPY_RP2PIO is handled in the raspberrypi tree.
 # Only for rp2 chips.
 # Assume not a rp2 build.
@@ -285,46 +315,54 @@ CFLAGS += -DCIRCUITPY_TOUCHIO=$(CIRCUITPY_TOUCHIO)
 CIRCUITPY_UHEAP ?= 0
 CFLAGS += -DCIRCUITPY_UHEAP=$(CIRCUITPY_UHEAP)
 
+# Secondary CDC is usually available if there are at least 8 endpoints.
+CIRCUITPY_USB_CDC ?= $(shell expr $(USB_NUM_EP) '>=' 8)
+CFLAGS += -DCIRCUITPY_USB_CDC=$(CIRCUITPY_USB_CDC)
+
 CIRCUITPY_USB_HID ?= 1
 CFLAGS += -DCIRCUITPY_USB_HID=$(CIRCUITPY_USB_HID)
 
+CIRCUITPY_USB_HID_CONSUMER ?= 1
+CFLAGS += -DCIRCUITPY_USB_HID_CONSUMER=$(CIRCUITPY_USB_HID_CONSUMER)
+
+CIRCUITPY_USB_HID_DIGITIZER ?= 0
+CFLAGS += -DCIRCUITPY_USB_HID_DIGITIZER=$(CIRCUITPY_USB_HID_DIGITIZER)
+
+CIRCUITPY_USB_HID_GAMEPAD ?= 1
+CFLAGS += -DCIRCUITPY_USB_HID_GAMEPAD=$(CIRCUITPY_USB_HID_GAMEPAD)
+
+CIRCUITPY_USB_HID_KEYBOARD ?= 1
+CFLAGS += -DCIRCUITPY_USB_HID_KEYBOARD=$(CIRCUITPY_USB_HID_KEYBOARD)
+
+CIRCUITPY_USB_HID_MOUSE ?= 1
+CFLAGS += -DCIRCUITPY_USB_HID_MOUSE=$(CIRCUITPY_USB_HID_MOUSE)
+
+CIRCUITPY_USB_HID_SYS_CONTROL ?= 0
+CFLAGS += -DCIRCUITPY_USB_HID_CONTROL=$(CIRCUITPY_USB_HID_CONTROL)
+
+CIRCUITPY_USB_HID_XAC_COMPATIBLE_GAMEPAD ?= 0
+CFLAGS += -DCIRCUITPY_USB_HID_XAC_COMPATIBLE_GAMEPAD=$(CIRCUITPY_USB_HID_XAC_COMPATIBLE_GAMEPAD)
+
 CIRCUITPY_USB_MIDI ?= 1
 CFLAGS += -DCIRCUITPY_USB_MIDI=$(CIRCUITPY_USB_MIDI)
 
+CIRCUITPY_USB_MSC ?= 1
+CFLAGS += -DCIRCUITPY_USB_MSC=$(CIRCUITPY_USB_MSC)
+
 # Defaulting this to OFF initially because it has only been tested on a
 # limited number of platforms, and the other platforms do not have this
 # setting in their mpconfigport.mk and/or mpconfigboard.mk files yet.
 CIRCUITPY_USB_VENDOR ?= 0
 CFLAGS += -DCIRCUITPY_USB_VENDOR=$(CIRCUITPY_USB_VENDOR)
 
-CIRCUITPY_PEW ?= 0
-CFLAGS += -DCIRCUITPY_PEW=$(CIRCUITPY_PEW)
+ifndef USB_NUM_EP
+$(error "USB_NUM_EP (number of USB endpoint pairs)must be defined")
+endif
 
 # For debugging.
 CIRCUITPY_USTACK ?= 0
 CFLAGS += -DCIRCUITPY_USTACK=$(CIRCUITPY_USTACK)
 
-# Non-module conditionals
-
-CIRCUITPY_BITBANG_APA102 ?= 0
-CFLAGS += -DCIRCUITPY_BITBANG_APA102=$(CIRCUITPY_BITBANG_APA102)
-
-# Should busio.I2C() check for pullups?
-# Some boards in combination with certain peripherals may not want this.
-CIRCUITPY_REQUIRE_I2C_PULLUPS ?= 1
-CFLAGS += -DCIRCUITPY_REQUIRE_I2C_PULLUPS=$(CIRCUITPY_REQUIRE_I2C_PULLUPS)
-
-# REPL over BLE
-CIRCUITPY_SERIAL_BLE ?= 0
-CFLAGS += -DCIRCUITPY_SERIAL_BLE=$(CIRCUITPY_SERIAL_BLE)
-
-CIRCUITPY_BLE_FILE_SERVICE ?= 0
-CFLAGS += -DCIRCUITPY_BLE_FILE_SERVICE=$(CIRCUITPY_BLE_FILE_SERVICE)
-
-# REPL over UART
-CIRCUITPY_SERIAL_UART ?= 0
-CFLAGS += -DCIRCUITPY_SERIAL_UART=$(CIRCUITPY_SERIAL_UART)
-
 # ulab numerics library
 CIRCUITPY_ULAB ?= $(CIRCUITPY_FULL_BUILD)
 CFLAGS += -DCIRCUITPY_ULAB=$(CIRCUITPY_ULAB)
@@ -335,10 +373,3 @@ CFLAGS += -DCIRCUITPY_WATCHDOG=$(CIRCUITPY_WATCHDOG)
 
 CIRCUITPY_WIFI ?= 0
 CFLAGS += -DCIRCUITPY_WIFI=$(CIRCUITPY_WIFI)
-
-# Enabled micropython.native decorator (experimental)
-CIRCUITPY_ENABLE_MPY_NATIVE ?= 0
-CFLAGS += -DCIRCUITPY_ENABLE_MPY_NATIVE=$(CIRCUITPY_ENABLE_MPY_NATIVE)
-
-CIRCUITPY_MSGPACK ?= $(CIRCUITPY_FULL_BUILD)
-CFLAGS += -DCIRCUITPY_MSGPACK=$(CIRCUITPY_MSGPACK)
diff --git a/py/stream.c b/py/stream.c
index ae702bb1b..0813c1d7f 100644
--- a/py/stream.c
+++ b/py/stream.c
@@ -99,14 +99,22 @@ const mp_stream_p_t *mp_get_stream_raise(mp_obj_t self_in, int flags) {
 
 STATIC mp_obj_t stream_read_generic(size_t n_args, const mp_obj_t *args, byte flags) {
     // What to do if sz < -1?  Python docs don't specify this case.
-    // CPython does a readall, but here we silently let negatives through,
-    // and they will cause a MemoryError.
+    // CPython does a readall, let's do the same.
     mp_int_t sz;
-    if (n_args == 1 || args[1] == mp_const_none || ((sz = mp_obj_get_int(args[1])) == -1)) {
-        return stream_readall(args[0]);
-    }
-
     const mp_stream_p_t *stream_p = mp_get_stream(args[0]);
+    if (stream_p->pyserial_read_compatibility) {
+        // Pyserial defaults to sz=1 if not specified.
+        if (n_args == 1) {
+            sz = 1;
+        } else {
+            // Pyserial treats negative size as 0.
+            sz = MAX(0, mp_obj_get_int(args[1]));
+        }
+    } else {
+        if (n_args == 1 || args[1] == mp_const_none || (sz = mp_obj_get_int(args[1])) <= -1) {
+            return stream_readall(args[0]);
+        }
+    }
 
     #if MICROPY_PY_BUILTINS_STR_UNICODE
     if (stream_p->is_text) {
@@ -284,7 +292,7 @@ STATIC mp_obj_t stream_readinto(size_t n_args, const mp_obj_t *args) {
     // https://docs.python.org/3/library/socket.html#socket.socket.recv_into
     mp_uint_t len = bufinfo.len;
     if (n_args > 2) {
-        if (mp_get_stream(args[0])->pyserial_compatibility) {
+        if (mp_get_stream(args[0])->pyserial_readinto_compatibility) {
             mp_raise_ValueError(translate("length argument not allowed for this type"));
         }
         len = mp_obj_get_int(args[2]);
@@ -297,7 +305,10 @@ STATIC mp_obj_t stream_readinto(size_t n_args, const mp_obj_t *args) {
     mp_uint_t out_sz = mp_stream_read_exactly(args[0], bufinfo.buf, len, &error);
     if (error != 0) {
         if (mp_is_nonblocking_error(error)) {
-            return mp_const_none;
+            // pyserial readinto never returns None, just 0.
+            return mp_get_stream(args[0])->pyserial_dont_return_none_compatibility
+                ? MP_OBJ_NEW_SMALL_INT(0)
+                : mp_const_none;
         }
         mp_raise_OSError(error);
     } else {
@@ -323,7 +334,10 @@ STATIC mp_obj_t stream_readall(mp_obj_t self_in) {
                 // If we read nothing, return None, just like read().
                 // Otherwise, return data read so far.
                 if (total_size == 0) {
-                    return mp_const_none;
+                    // pyserial read() never returns None, just b''.
+                    return stream_p->pyserial_dont_return_none_compatibility
+                        ? mp_const_empty_bytes
+                        : mp_const_none;
                 }
                 break;
             }
diff --git a/py/stream.h b/py/stream.h
index be6b23d40..c05dcfc50 100644
--- a/py/stream.h
+++ b/py/stream.h
@@ -72,7 +72,9 @@ typedef struct _mp_stream_p_t {
     mp_uint_t (*write)(mp_obj_t obj, const void *buf, mp_uint_t size, int *errcode);
     mp_uint_t (*ioctl)(mp_obj_t obj, mp_uint_t request, uintptr_t arg, int *errcode);
     mp_uint_t is_text : 1; // default is bytes, set this for text stream
-    bool pyserial_compatibility: 1;  // adjust API to match pyserial more closely
+    bool pyserial_readinto_compatibility: 1;         // Disallow size parameter in readinto()
+    bool pyserial_read_compatibility: 1;             // Disallow omitting read(size) size parameter
+    bool pyserial_dont_return_none_compatibility: 1; // Don't return None for read() or readinto()
 } mp_stream_p_t;
 
 MP_DECLARE_CONST_FUN_OBJ_VAR_BETWEEN(mp_stream_read_obj);
diff --git a/shared-bindings/_bleio/CharacteristicBuffer.c b/shared-bindings/_bleio/CharacteristicBuffer.c
index 4d6c836c1..333b275ff 100644
--- a/shared-bindings/_bleio/CharacteristicBuffer.c
+++ b/shared-bindings/_bleio/CharacteristicBuffer.c
@@ -231,8 +231,8 @@ STATIC const mp_stream_p_t characteristic_buffer_stream_p = {
     .write = bleio_characteristic_buffer_write,
     .ioctl = bleio_characteristic_buffer_ioctl,
     .is_text = false,
-    // Match PySerial when possible, such as disallowing optional length argument for .readinto()
-    .pyserial_compatibility = true,
+    // Disallow readinto() size parameter.
+    .pyserial_readinto_compatibility = true,
 };
 
 
diff --git a/shared-bindings/busio/UART.c b/shared-bindings/busio/UART.c
index bf0b7e721..f48109fde 100644
--- a/shared-bindings/busio/UART.c
+++ b/shared-bindings/busio/UART.c
@@ -415,8 +415,8 @@ STATIC const mp_stream_p_t uart_stream_p = {
     .write = busio_uart_write,
     .ioctl = busio_uart_ioctl,
     .is_text = false,
-    // Match PySerial when possible, such as disallowing optional length argument for .readinto()
-    .pyserial_compatibility = true,
+    // Disallow optional length argument for .readinto()
+    .pyserial_readinto_compatibility = true,
 };
 
 const mp_obj_type_t busio_uart_type = {
diff --git a/shared-bindings/supervisor/Runtime.c b/shared-bindings/supervisor/Runtime.c
index 8e0259a3b..283c8a1d6 100755
--- a/shared-bindings/supervisor/Runtime.c
+++ b/shared-bindings/supervisor/Runtime.c
@@ -55,59 +55,46 @@ STATIC supervisor_run_reason_t _run_reason;
 //|     serial_connected: bool
 //|     """Returns the USB serial communication status (read-only)."""
 //|
-
-STATIC mp_obj_t supervisor_get_serial_connected(mp_obj_t self){
-    if (!common_hal_get_serial_connected()) {
-        return mp_const_false;
-    }
-    else {
-        return mp_const_true;
-    }
+STATIC mp_obj_t supervisor_runtime_get_serial_connected(mp_obj_t self){
+    return mp_obj_new_bool(common_hal_supervisor_runtime_get_serial_connected());
 }
-MP_DEFINE_CONST_FUN_OBJ_1(supervisor_get_serial_connected_obj, supervisor_get_serial_connected);
+MP_DEFINE_CONST_FUN_OBJ_1(supervisor_runtime_get_serial_connected_obj, supervisor_runtime_get_serial_connected);
 
-const mp_obj_property_t supervisor_serial_connected_obj = {
+const mp_obj_property_t supervisor_runtime_serial_connected_obj = {
     .base.type = &mp_type_property,
-    .proxy = {(mp_obj_t)&supervisor_get_serial_connected_obj,
+    .proxy = {(mp_obj_t)&supervisor_runtime_get_serial_connected_obj,
               (mp_obj_t)&mp_const_none_obj,
               (mp_obj_t)&mp_const_none_obj},
 };
 
-
 //|     serial_bytes_available: int
 //|     """Returns the whether any bytes are available to read
 //|     on the USB serial input.  Allows for polling to see whether
 //|     to call the built-in input() or wait. (read-only)"""
 //|
-STATIC mp_obj_t supervisor_get_serial_bytes_available(mp_obj_t self){
-    if (!common_hal_get_serial_bytes_available()) {
-        return mp_const_false;
-    }
-    else {
-        return mp_const_true;
-    }
+STATIC mp_obj_t supervisor_runtime_get_serial_bytes_available(mp_obj_t self){
+    return mp_obj_new_bool(common_hal_supervisor_runtime_get_serial_bytes_available());
 }
-MP_DEFINE_CONST_FUN_OBJ_1(supervisor_get_serial_bytes_available_obj, supervisor_get_serial_bytes_available);
+MP_DEFINE_CONST_FUN_OBJ_1(supervisor_runtime_get_serial_bytes_available_obj, supervisor_runtime_get_serial_bytes_available);
 
-const mp_obj_property_t supervisor_serial_bytes_available_obj = {
+const mp_obj_property_t supervisor_runtime_serial_bytes_available_obj = {
     .base.type = &mp_type_property,
-    .proxy = {(mp_obj_t)&supervisor_get_serial_bytes_available_obj,
+    .proxy = {(mp_obj_t)&supervisor_runtime_get_serial_bytes_available_obj,
               (mp_obj_t)&mp_const_none_obj,
               (mp_obj_t)&mp_const_none_obj},
 };
 
-
 //|     run_reason: RunReason
 //|     """Returns why CircuitPython started running this particular time."""
 //|
-STATIC mp_obj_t supervisor_get_run_reason(mp_obj_t self) {
+STATIC mp_obj_t supervisor_runtime_get_run_reason(mp_obj_t self) {
     return cp_enum_find(&supervisor_run_reason_type, _run_reason);
 }
-MP_DEFINE_CONST_FUN_OBJ_1(supervisor_get_run_reason_obj, supervisor_get_run_reason);
+MP_DEFINE_CONST_FUN_OBJ_1(supervisor_runtime_get_run_reason_obj, supervisor_runtime_get_run_reason);
 
-const mp_obj_property_t supervisor_run_reason_obj = {
+const mp_obj_property_t supervisor_runtime_run_reason_obj = {
     .base.type = &mp_type_property,
-    .proxy = {(mp_obj_t)&supervisor_get_run_reason_obj,
+    .proxy = {(mp_obj_t)&supervisor_runtime_get_run_reason_obj,
               (mp_obj_t)&mp_const_none_obj,
               (mp_obj_t)&mp_const_none_obj},
 };
@@ -117,9 +104,9 @@ void supervisor_set_run_reason(supervisor_run_reason_t run_reason) {
 }
 
 STATIC const mp_rom_map_elem_t supervisor_runtime_locals_dict_table[] = {
-    { MP_ROM_QSTR(MP_QSTR_serial_connected), MP_ROM_PTR(&supervisor_serial_connected_obj) },
-    { MP_ROM_QSTR(MP_QSTR_serial_bytes_available), MP_ROM_PTR(&supervisor_serial_bytes_available_obj) },
-    { MP_ROM_QSTR(MP_QSTR_run_reason), MP_ROM_PTR(&supervisor_run_reason_obj) },
+    { MP_ROM_QSTR(MP_QSTR_serial_connected), MP_ROM_PTR(&supervisor_runtime_serial_connected_obj) },
+    { MP_ROM_QSTR(MP_QSTR_serial_bytes_available), MP_ROM_PTR(&supervisor_runtime_serial_bytes_available_obj) },
+    { MP_ROM_QSTR(MP_QSTR_run_reason), MP_ROM_PTR(&supervisor_runtime_run_reason_obj) },
 };
 
 STATIC MP_DEFINE_CONST_DICT(supervisor_runtime_locals_dict, supervisor_runtime_locals_dict_table);
diff --git a/shared-bindings/supervisor/Runtime.h b/shared-bindings/supervisor/Runtime.h
index 51ed7604d..6874ac744 100755
--- a/shared-bindings/supervisor/Runtime.h
+++ b/shared-bindings/supervisor/Runtime.h
@@ -36,12 +36,12 @@ extern const mp_obj_type_t supervisor_runtime_type;
 
 void supervisor_set_run_reason(supervisor_run_reason_t run_reason);
 
-bool common_hal_get_serial_connected(void);
+bool common_hal_supervisor_runtime_get_serial_connected(void);
 
-bool common_hal_get_serial_bytes_available(void);
+bool common_hal_supervisor_runtime_get_serial_bytes_available(void);
 
 //TODO: placeholders for future functions
-//bool common_hal_get_repl_active(void);
-//bool common_hal_get_usb_enumerated(void);
+//bool common_hal_get_supervisor_runtime_repl_active(void);
+//bool common_hal_get_supervisor_runtime_usb_enumerated(void);
 
 #endif // MICROPY_INCLUDED_SHARED_BINDINGS_SUPERVISOR_RUNTIME_H
diff --git a/shared-bindings/usb_cdc/Serial.c b/shared-bindings/usb_cdc/Serial.c
new file mode 100644
index 000000000..c813dce5b
--- /dev/null
+++ b/shared-bindings/usb_cdc/Serial.c
@@ -0,0 +1,293 @@
+/*
+ * This file is part of the Micro Python project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Dan Halbert for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <stdint.h>
+
+#include "shared-bindings/usb_cdc/Serial.h"
+#include "shared-bindings/util.h"
+
+#include "py/ioctl.h"
+#include "py/objproperty.h"
+#include "py/runtime.h"
+#include "py/stream.h"
+#include "supervisor/shared/translate.h"
+
+//| class Serial:
+//|     """Receives cdc commands over USB"""
+//|
+//|     def __init__(self) -> None:
+//|         """You cannot create an instance of `usb_cdc.Serial`.
+//|
+//|         Serial objects are pre-constructed for each CDC device in the USB
+//|         descriptor and added to the ``usb_cdc.ports`` tuple."""
+//|         ...
+//|
+
+//|     def read(self, size: int = 1) -> bytes:
+//|         """Read at most ``size`` bytes. If ``size`` exceeds the internal buffer size
+//|         only the bytes in the buffer will be read. If `timeout` is > 0 or ``None``,
+//|         and fewer than ``size`` bytes are available, keep waiting until the timeout
+//|         expires or ``size`` bytes are available.
+//|
+//|         :return: Data read
+//|         :rtype: bytes"""
+//|         ...
+//|
+//|     def readinto(self, buf: WriteableBuffer) -> int:
+//|         """Read bytes into the ``buf``.  If ``nbytes`` is specified then read at most
+//|         that many bytes, subject to `timeout`.  Otherwise, read at most ``len(buf)`` bytes.
+//|
+//|         :return: number of bytes read and stored into ``buf``
+//|         :rtype: bytes"""
+//|         ...
+//|
+//|     def write(self, buf: ReadableBuffer) -> int:
+//|         """Write as many bytes as possible from the buffer of bytes.
+//|
+//|         :return: the number of bytes written
+//|         :rtype: int"""
+//|         ...
+//|
+//|     def flush(self) -> None:
+//|         """Force out any unwritten bytes, waiting until they are written."""
+//|         ...
+//|
+
+// These three methods are used by the shared stream methods.
+STATIC mp_uint_t usb_cdc_serial_read_stream(mp_obj_t self_in, void *buf_in, mp_uint_t size, int *errcode) {
+    usb_cdc_serial_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    byte *buf = buf_in;
+
+    // make sure we want at least 1 char
+    if (size == 0) {
+        return 0;
+    }
+
+    return common_hal_usb_cdc_serial_read(self, buf, size, errcode);
+}
+
+STATIC mp_uint_t usb_cdc_serial_write_stream(mp_obj_t self_in, const void *buf_in, mp_uint_t size, int *errcode) {
+    usb_cdc_serial_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    const byte *buf = buf_in;
+
+    return common_hal_usb_cdc_serial_write(self, buf, size, errcode);
+}
+
+STATIC mp_uint_t usb_cdc_serial_ioctl_stream(mp_obj_t self_in, mp_uint_t request, mp_uint_t arg, int *errcode) {
+    usb_cdc_serial_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    mp_uint_t ret = 0;
+    switch (request) {
+        case MP_IOCTL_POLL: {
+            mp_uint_t flags = arg;
+            ret = 0;
+            if ((flags & MP_IOCTL_POLL_RD) && common_hal_usb_cdc_serial_get_in_waiting(self) > 0) {
+                ret |= MP_IOCTL_POLL_RD;
+            }
+            if ((flags & MP_IOCTL_POLL_WR) && common_hal_usb_cdc_serial_get_out_waiting(self) == 0) {
+                ret |= MP_IOCTL_POLL_WR;
+            }
+            break;
+        }
+
+        case MP_STREAM_FLUSH:
+            common_hal_usb_cdc_serial_flush(self);
+            break;
+
+        default:
+            *errcode = MP_EINVAL;
+            ret = MP_STREAM_ERROR;
+    }
+    return ret;
+}
+
+//|     connected: bool
+//|     """True if this Serial is connected to a host. (read-only)"""
+//|
+STATIC mp_obj_t usb_cdc_serial_get_connected(mp_obj_t self_in) {
+    usb_cdc_serial_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    return mp_obj_new_bool(common_hal_usb_cdc_serial_get_connected(self));
+}
+MP_DEFINE_CONST_FUN_OBJ_1(usb_cdc_serial_get_connected_obj, usb_cdc_serial_get_connected);
+
+const mp_obj_property_t usb_cdc_serial_connected_obj = {
+    .base.type = &mp_type_property,
+    .proxy = {(mp_obj_t)&usb_cdc_serial_get_connected_obj,
+              (mp_obj_t)&mp_const_none_obj,
+              (mp_obj_t)&mp_const_none_obj},
+};
+
+//|     in_waiting: int
+//|     """Returns the number of bytes waiting to be read on the USB serial input. (read-only)"""
+//|
+STATIC mp_obj_t usb_cdc_serial_get_in_waiting(mp_obj_t self_in) {
+    usb_cdc_serial_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    return mp_obj_new_int(common_hal_usb_cdc_serial_get_in_waiting(self));
+}
+MP_DEFINE_CONST_FUN_OBJ_1(usb_cdc_serial_get_in_waiting_obj, usb_cdc_serial_get_in_waiting);
+
+const mp_obj_property_t usb_cdc_serial_in_waiting_obj = {
+    .base.type = &mp_type_property,
+    .proxy = {(mp_obj_t)&usb_cdc_serial_get_in_waiting_obj,
+              (mp_obj_t)&mp_const_none_obj,
+              (mp_obj_t)&mp_const_none_obj},
+};
+
+//|     out_waiting: int
+//|     """Returns the number of bytes waiting to be written on the USB serial output. (read-only)"""
+//|
+STATIC mp_obj_t usb_cdc_serial_get_out_waiting(mp_obj_t self_in) {
+    usb_cdc_serial_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    return mp_obj_new_int(common_hal_usb_cdc_serial_get_out_waiting(self));
+}
+MP_DEFINE_CONST_FUN_OBJ_1(usb_cdc_serial_get_out_waiting_obj, usb_cdc_serial_get_out_waiting);
+
+const mp_obj_property_t usb_cdc_serial_out_waiting_obj = {
+    .base.type = &mp_type_property,
+    .proxy = {(mp_obj_t)&usb_cdc_serial_get_out_waiting_obj,
+              (mp_obj_t)&mp_const_none_obj,
+              (mp_obj_t)&mp_const_none_obj},
+};
+
+//|     def reset_input_buffer(self) -> None:
+//|         """Clears any unread bytes."""
+//|         ...
+//|
+STATIC mp_obj_t usb_cdc_serial_reset_input_buffer(mp_obj_t self_in) {
+    usb_cdc_serial_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    common_hal_usb_cdc_serial_reset_input_buffer(self);
+    return mp_const_none;
+}
+MP_DEFINE_CONST_FUN_OBJ_1(usb_cdc_serial_reset_input_buffer_obj, usb_cdc_serial_reset_input_buffer);
+
+//|     def reset_output_buffer(self) -> None:
+//|         """Clears any unwritten bytes."""
+//|         ...
+//|
+STATIC mp_obj_t usb_cdc_serial_reset_output_buffer(mp_obj_t self_in) {
+    usb_cdc_serial_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    common_hal_usb_cdc_serial_reset_output_buffer(self);
+    return mp_const_none;
+}
+MP_DEFINE_CONST_FUN_OBJ_1(usb_cdc_serial_reset_output_buffer_obj, usb_cdc_serial_reset_output_buffer);
+
+//|     timeout: Optional[float]
+//|     """The initial value of `timeout` is ``None``. If ``None``, wait indefinitely to satisfy
+//|     the conditions of a read operation. If 0, do not wait. If > 0, wait only ``timeout`` seconds."""
+//|
+STATIC mp_obj_t usb_cdc_serial_get_timeout(mp_obj_t self_in) {
+    usb_cdc_serial_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    mp_float_t timeout = common_hal_usb_cdc_serial_get_timeout(self);
+    return (timeout < 0.0f) ? mp_const_none : mp_obj_new_float(self->timeout);
+}
+MP_DEFINE_CONST_FUN_OBJ_1(usb_cdc_serial_get_timeout_obj, usb_cdc_serial_get_timeout);
+
+STATIC mp_obj_t usb_cdc_serial_set_timeout(mp_obj_t self_in, mp_obj_t timeout_in) {
+    usb_cdc_serial_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    common_hal_usb_cdc_serial_set_timeout(self,
+        timeout_in == mp_const_none ? -1.0f : mp_obj_get_float(timeout_in));
+    return mp_const_none;
+}
+MP_DEFINE_CONST_FUN_OBJ_2(usb_cdc_serial_set_timeout_obj, usb_cdc_serial_set_timeout);
+
+const mp_obj_property_t usb_cdc_serial_timeout_obj = {
+    .base.type = &mp_type_property,
+    .proxy = {(mp_obj_t)&usb_cdc_serial_get_timeout_obj,
+              (mp_obj_t)&usb_cdc_serial_set_timeout_obj,
+              (mp_obj_t)&mp_const_none_obj},
+};
+
+//|     write_timeout: Optional[float]
+//|     """The initial value of `write_timeout` is ``None``. If ``None``, wait indefinitely to finish
+//|     writing all the bytes passed to ``write()``.If 0, do not wait.
+//|     If > 0, wait only ``write_timeout`` seconds."""
+//|
+STATIC mp_obj_t usb_cdc_serial_get_write_timeout(mp_obj_t self_in) {
+    usb_cdc_serial_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    mp_float_t write_timeout = common_hal_usb_cdc_serial_get_write_timeout(self);
+    return (write_timeout < 0.0f) ? mp_const_none : mp_obj_new_float(self->write_timeout);
+}
+MP_DEFINE_CONST_FUN_OBJ_1(usb_cdc_serial_get_write_timeout_obj, usb_cdc_serial_get_write_timeout);
+
+STATIC mp_obj_t usb_cdc_serial_set_write_timeout(mp_obj_t self_in, mp_obj_t write_timeout_in) {
+    usb_cdc_serial_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    common_hal_usb_cdc_serial_set_write_timeout(self,
+        write_timeout_in == mp_const_none ? -1.0f : mp_obj_get_float(write_timeout_in));
+    return mp_const_none;
+}
+MP_DEFINE_CONST_FUN_OBJ_2(usb_cdc_serial_set_write_timeout_obj, usb_cdc_serial_set_write_timeout);
+
+const mp_obj_property_t usb_cdc_serial_write_timeout_obj = {
+    .base.type = &mp_type_property,
+    .proxy = {(mp_obj_t)&usb_cdc_serial_get_write_timeout_obj,
+              (mp_obj_t)&usb_cdc_serial_set_write_timeout_obj,
+              (mp_obj_t)&mp_const_none_obj},
+};
+
+
+STATIC const mp_rom_map_elem_t usb_cdc_serial_locals_dict_table[] = {
+    // Standard stream methods.
+    { MP_ROM_QSTR(MP_QSTR_flush),        MP_ROM_PTR(&mp_stream_flush_obj) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_read),     MP_ROM_PTR(&mp_stream_read_obj) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_readinto), MP_ROM_PTR(&mp_stream_readinto_obj) },
+    { MP_ROM_QSTR(MP_QSTR_readline),     MP_ROM_PTR(&mp_stream_unbuffered_readline_obj)},
+    { MP_ROM_QSTR(MP_QSTR_readlines),    MP_ROM_PTR(&mp_stream_unbuffered_readlines_obj)},
+    { MP_OBJ_NEW_QSTR(MP_QSTR_write),    MP_ROM_PTR(&mp_stream_write_obj) },
+
+    // Other pyserial-inspired attributes.
+    { MP_OBJ_NEW_QSTR(MP_QSTR_in_waiting),          MP_ROM_PTR(&usb_cdc_serial_in_waiting_obj) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_out_waiting),         MP_ROM_PTR(&usb_cdc_serial_out_waiting_obj) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_reset_input_buffer),  MP_ROM_PTR(&usb_cdc_serial_reset_input_buffer_obj) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_reset_output_buffer), MP_ROM_PTR(&usb_cdc_serial_reset_output_buffer_obj) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_timeout),             MP_ROM_PTR(&usb_cdc_serial_timeout_obj) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_write_timeout),       MP_ROM_PTR(&usb_cdc_serial_write_timeout_obj) },
+
+    // Not in pyserial protocol.
+    { MP_OBJ_NEW_QSTR(MP_QSTR_connected),     MP_ROM_PTR(&usb_cdc_serial_connected_obj) },
+
+
+
+};
+STATIC MP_DEFINE_CONST_DICT(usb_cdc_serial_locals_dict, usb_cdc_serial_locals_dict_table);
+
+STATIC const mp_stream_p_t usb_cdc_serial_stream_p = {
+    MP_PROTO_IMPLEMENT(MP_QSTR_protocol_stream)
+    .read = usb_cdc_serial_read_stream,
+    .write = usb_cdc_serial_write_stream,
+    .ioctl = usb_cdc_serial_ioctl_stream,
+    .is_text = false,
+    .pyserial_read_compatibility = true,
+    .pyserial_readinto_compatibility = true,
+    .pyserial_dont_return_none_compatibility = true,
+};
+
+const mp_obj_type_t usb_cdc_serial_type = {
+    { &mp_type_type },
+    .name = MP_QSTR_Serial,
+    .getiter = mp_identity_getiter,
+    .iternext = mp_stream_unbuffered_iter,
+    .protocol = &usb_cdc_serial_stream_p,
+    .locals_dict = (mp_obj_dict_t*)&usb_cdc_serial_locals_dict,
+};
diff --git a/shared-bindings/usb_cdc/Serial.h b/shared-bindings/usb_cdc/Serial.h
new file mode 100644
index 000000000..cdf5c3a91
--- /dev/null
+++ b/shared-bindings/usb_cdc/Serial.h
@@ -0,0 +1,53 @@
+/*
+ * This file is part of the Micro Python project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Dan Halbert for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef MICROPY_INCLUDED_SHARED_BINDINGS_USB_CDC_SERIAL_H
+#define MICROPY_INCLUDED_SHARED_BINDINGS_USB_CDC_SERIAL_H
+
+#include "shared-module/usb_cdc/Serial.h"
+
+extern const mp_obj_type_t usb_cdc_serial_type;
+
+extern size_t common_hal_usb_cdc_serial_read(usb_cdc_serial_obj_t *self, uint8_t *data, size_t len, int *errcode);
+extern size_t common_hal_usb_cdc_serial_write(usb_cdc_serial_obj_t *self, const uint8_t *data, size_t len, int *errcode);
+
+extern uint32_t common_hal_usb_cdc_serial_get_in_waiting(usb_cdc_serial_obj_t *self);
+extern uint32_t common_hal_usb_cdc_serial_get_out_waiting(usb_cdc_serial_obj_t *self);
+
+extern void common_hal_usb_cdc_serial_reset_input_buffer(usb_cdc_serial_obj_t *self);
+extern uint32_t common_hal_usb_cdc_serial_reset_output_buffer(usb_cdc_serial_obj_t *self);
+
+extern uint32_t common_hal_usb_cdc_serial_flush(usb_cdc_serial_obj_t *self);
+
+extern bool common_hal_usb_cdc_serial_get_connected(usb_cdc_serial_obj_t *self);
+
+extern mp_float_t common_hal_usb_cdc_serial_get_timeout(usb_cdc_serial_obj_t *self);
+extern void common_hal_usb_cdc_serial_set_timeout(usb_cdc_serial_obj_t *self, mp_float_t timeout);
+
+extern mp_float_t common_hal_usb_cdc_serial_get_write_timeout(usb_cdc_serial_obj_t *self);
+extern void common_hal_usb_cdc_serial_set_write_timeout(usb_cdc_serial_obj_t *self, mp_float_t write_timeout);
+
+#endif  // MICROPY_INCLUDED_SHARED_BINDINGS_USB_CDC_SERIAL_H
diff --git a/shared-bindings/usb_cdc/__init__.c b/shared-bindings/usb_cdc/__init__.c
new file mode 100644
index 000000000..eb9c25e00
--- /dev/null
+++ b/shared-bindings/usb_cdc/__init__.c
@@ -0,0 +1,59 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Dan Halbertfor Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <stdint.h>
+
+#include "py/obj.h"
+#include "py/runtime.h"
+
+#include "shared-bindings/usb_cdc/__init__.h"
+#include "shared-bindings/usb_cdc/Serial.h"
+
+#include "py/runtime.h"
+
+//| """USB CDC Serial streams
+//|
+//| The `usb_cdc` module allows access to USB CDC (serial) communications."""
+//|
+//| serials: Tuple[Serial, ...]
+//| """Tuple of all CDC streams. Each item is a `Serial`.
+//| ``serials[0]`` is the USB REPL connection.
+//| ``serials[1]`` is a second USB serial connection, unconnected to the REPL.
+//| """
+//|
+
+static const mp_map_elem_t usb_cdc_module_globals_table[] = {
+    { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_usb_cdc) },
+    { MP_ROM_QSTR(MP_QSTR_Serial),   MP_OBJ_FROM_PTR(&usb_cdc_serial_type) },
+    { MP_ROM_QSTR(MP_QSTR_serials),  MP_OBJ_FROM_PTR(&usb_cdc_serials_tuple) },
+};
+
+static MP_DEFINE_CONST_DICT(usb_cdc_module_globals, usb_cdc_module_globals_table);
+
+const mp_obj_module_t usb_cdc_module = {
+    .base = { &mp_type_module },
+    .globals = (mp_obj_dict_t*)&usb_cdc_module_globals,
+};
diff --git a/shared-bindings/usb_cdc/__init__.h b/shared-bindings/usb_cdc/__init__.h
new file mode 100644
index 000000000..e81d243e6
--- /dev/null
+++ b/shared-bindings/usb_cdc/__init__.h
@@ -0,0 +1,32 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Dan Halbert for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef MICROPY_INCLUDED_SHARED_BINDINGS_USB_CDC___INIT___H
+#define MICROPY_INCLUDED_SHARED_BINDINGS_USB_CDC___INIT___H
+
+#include "shared-module/usb_cdc/__init__.h"
+
+#endif  // MICROPY_INCLUDED_SHARED_BINDINGS_USB_CDC___INIT___H
diff --git a/shared-module/usb_cdc/Serial.c b/shared-module/usb_cdc/Serial.c
new file mode 100644
index 000000000..6037fddcc
--- /dev/null
+++ b/shared-module/usb_cdc/Serial.c
@@ -0,0 +1,147 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Dan Halbert for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "lib/utils/interrupt_char.h"
+#include "shared-module/usb_cdc/Serial.h"
+#include "supervisor/shared/tick.h"
+
+#include "tusb.h"
+
+size_t common_hal_usb_cdc_serial_read(usb_cdc_serial_obj_t *self, uint8_t *data, size_t len, int *errcode) {
+
+    const bool wait_forever = self->timeout < 0.0f;
+    const bool wait_for_timeout = self->timeout > 0.0f;
+
+    // Read up to len bytes immediately.
+    // The number of bytes read will not be larger than what is already in the TinyUSB FIFO.
+    uint32_t total_num_read = tud_cdc_n_read(self->idx, data, len);
+
+    if (wait_forever || wait_for_timeout) {
+        // Read more if we have time.
+        uint64_t timeout_ms = self->timeout * 1000;  // Junk value if timeout < 0.
+        uint64_t start_ticks = supervisor_ticks_ms64();
+
+        uint32_t num_read = 0;
+        while (total_num_read < len &&
+               (wait_forever || supervisor_ticks_ms64() - start_ticks <= timeout_ms)) {
+
+            // Wait for a bit, and check for ctrl-C.
+            RUN_BACKGROUND_TASKS;
+            if (mp_hal_is_interrupted()) {
+                return 0;
+            }
+
+            // Advance buffer pointer and reduce number of bytes that need to be read.
+            len -= num_read;
+            data += num_read;
+
+            // Try to read another batch of bytes.
+            num_read = tud_cdc_n_read(self->idx, data, len);
+            total_num_read += num_read;
+        }
+    }
+
+    return total_num_read;
+}
+
+size_t common_hal_usb_cdc_serial_write(usb_cdc_serial_obj_t *self, const uint8_t *data, size_t len, int *errcode) {
+    const bool wait_forever = self->write_timeout < 0.0f;
+    const bool wait_for_timeout = self->write_timeout > 0.0f;
+
+    // Write as many bytes as possible immediately.
+    // The number of bytes written at once will not be larger than what can fit in the TinyUSB FIFO.
+    uint32_t total_num_written = tud_cdc_n_write(self->idx, data, len);
+    tud_cdc_n_write_flush(self->idx);
+
+    if (wait_forever || wait_for_timeout) {
+        // Write more if we have time.
+        uint64_t timeout_ms = self->write_timeout * 1000;  // Junk value if write_timeout < 0.
+        uint64_t start_ticks = supervisor_ticks_ms64();
+
+        uint32_t num_written = 0;
+        while (total_num_written < len &&
+               (wait_forever || supervisor_ticks_ms64() - start_ticks <= timeout_ms)) {
+
+            // Wait for a bit, and check for ctrl-C.
+            RUN_BACKGROUND_TASKS;
+            if (mp_hal_is_interrupted()) {
+                return 0;
+            }
+
+            // Advance buffer pointer and reduce number of bytes that need to be written.
+            len -= num_written;
+            data += num_written;
+
+            // Try to write another batch of bytes.
+            num_written = tud_cdc_n_write(self->idx, data, len);
+            tud_cdc_n_write_flush(self->idx);
+            total_num_written += num_written;
+        }
+    }
+
+    return total_num_written;
+}
+
+uint32_t common_hal_usb_cdc_serial_get_in_waiting(usb_cdc_serial_obj_t *self) {
+    return tud_cdc_n_available(self->idx);
+}
+
+uint32_t common_hal_usb_cdc_serial_get_out_waiting(usb_cdc_serial_obj_t *self) {
+    // Return number of FIFO bytes currently occupied.
+    return CFG_TUD_CDC_TX_BUFSIZE - tud_cdc_n_write_available(self->idx);
+}
+
+void common_hal_usb_cdc_serial_reset_input_buffer(usb_cdc_serial_obj_t *self) {
+    tud_cdc_n_read_flush(self->idx);
+}
+
+uint32_t common_hal_usb_cdc_serial_reset_output_buffer(usb_cdc_serial_obj_t *self) {
+    return tud_cdc_n_write_clear(self->idx);
+}
+
+uint32_t common_hal_usb_cdc_serial_flush(usb_cdc_serial_obj_t *self) {
+    return tud_cdc_n_write_flush(self->idx);
+}
+
+bool common_hal_usb_cdc_serial_get_connected(usb_cdc_serial_obj_t *self) {
+    return tud_cdc_n_connected(self->idx);
+}
+
+mp_float_t common_hal_usb_cdc_serial_get_timeout(usb_cdc_serial_obj_t *self) {
+    return self->timeout;
+}
+
+void common_hal_usb_cdc_serial_set_timeout(usb_cdc_serial_obj_t *self, mp_float_t timeout) {
+    self->timeout = timeout;
+}
+
+mp_float_t common_hal_usb_cdc_serial_get_write_timeout(usb_cdc_serial_obj_t *self) {
+    return self->write_timeout;
+}
+
+void common_hal_usb_cdc_serial_set_write_timeout(usb_cdc_serial_obj_t *self, mp_float_t write_timeout) {
+    self->write_timeout = write_timeout;
+}
diff --git a/shared-module/usb_cdc/Serial.h b/shared-module/usb_cdc/Serial.h
new file mode 100644
index 000000000..ddf78eefa
--- /dev/null
+++ b/shared-module/usb_cdc/Serial.h
@@ -0,0 +1,39 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Dan Halbert for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef SHARED_MODULE_USB_CDC_SERIAL_H
+#define SHARED_MODULE_USB_CDC_SERIAL_H
+
+#include "py/obj.h"
+
+typedef struct {
+    mp_obj_base_t base;
+    mp_float_t timeout;       // if negative, wait forever.
+    mp_float_t write_timeout; // if negative, wait forever.
+    uint8_t idx;              // which CDC device?
+} usb_cdc_serial_obj_t;
+
+#endif // SHARED_MODULE_USB_CDC_SERIAL_H
diff --git a/shared-module/usb_cdc/__init__.c b/shared-module/usb_cdc/__init__.c
new file mode 100644
index 000000000..fe05cb107
--- /dev/null
+++ b/shared-module/usb_cdc/__init__.c
@@ -0,0 +1,61 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Dan Halbert for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "genhdr/autogen_usb_descriptor.h"
+#include "py/gc.h"
+#include "py/obj.h"
+#include "py/mphal.h"
+#include "py/runtime.h"
+#include "py/objtuple.h"
+#include "shared-bindings/usb_cdc/__init__.h"
+#include "shared-bindings/usb_cdc/Serial.h"
+#include "tusb.h"
+
+#if CFG_TUD_CDC != 2
+#error CFG_TUD_CDC must be exactly 2
+#endif
+
+static usb_cdc_serial_obj_t serial_objs[CFG_TUD_CDC] = {
+    {   .base.type = &usb_cdc_serial_type,
+        .timeout = -1.0f,
+        .write_timeout = -1.0f,
+        .idx = 0,
+    }, {
+        .base.type = &usb_cdc_serial_type,
+        .timeout = -1.0f,
+        .write_timeout = -1.0f,
+        .idx = 1,
+    }
+};
+
+const mp_rom_obj_tuple_t usb_cdc_serials_tuple = {
+    .base.type = &mp_type_tuple,
+    .len = CFG_TUD_CDC,
+    .items = {
+        &serial_objs[0],
+        &serial_objs[1],
+    },
+};
diff --git a/shared-module/usb_cdc/__init__.h b/shared-module/usb_cdc/__init__.h
new file mode 100644
index 000000000..9de3eb2fa
--- /dev/null
+++ b/shared-module/usb_cdc/__init__.h
@@ -0,0 +1,34 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Dan Halbert for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef SHARED_MODULE_USB_CDC___INIT___H
+#define SHARED_MODULE_USB_CDC___INIT___H
+
+#include "py/objtuple.h"
+
+extern const mp_rom_obj_tuple_t usb_cdc_serials_tuple;
+
+#endif /* SHARED_MODULE_USB_CDC___INIT___H */
diff --git a/supervisor/shared/serial.c b/supervisor/shared/serial.c
index b9feb04f2..9cc12de51 100644
--- a/supervisor/shared/serial.c
+++ b/supervisor/shared/serial.c
@@ -118,7 +118,6 @@ bool serial_bytes_available(void) {
     return tud_cdc_available() > 0;
 #endif
 }
-
 void serial_write_substring(const char* text, uint32_t length) {
     if (length == 0) {
         return;
diff --git a/supervisor/shared/usb/tusb_config.h b/supervisor/shared/usb/tusb_config.h
index d3a35f537..bff7bd6b5 100644
--- a/supervisor/shared/usb/tusb_config.h
+++ b/supervisor/shared/usb/tusb_config.h
@@ -61,10 +61,15 @@
 // DEVICE CONFIGURATION
 //--------------------------------------------------------------------+
 
-#define CFG_TUD_ENDOINT0_SIZE       64
+#define CFG_TUD_ENDPOINT0_SIZE       64
 
 //------------- CLASS -------------//
+
+// Could be 2 if secondary CDC channel requested.
+#ifndef CFG_TUD_CDC
 #define CFG_TUD_CDC                 1
+#endif
+
 #define CFG_TUD_MSC                 1
 #define CFG_TUD_HID                 CIRCUITPY_USB_HID
 #define CFG_TUD_MIDI                CIRCUITPY_USB_MIDI
diff --git a/supervisor/shared/usb/usb.c b/supervisor/shared/usb/usb.c
index 43564d5d5..5b020b8a0 100644
--- a/supervisor/shared/usb/usb.c
+++ b/supervisor/shared/usb/usb.c
@@ -26,7 +26,6 @@
 
 #include "py/objstr.h"
 #include "shared-bindings/microcontroller/Processor.h"
-#include "shared-module/usb_midi/__init__.h"
 #include "supervisor/background_callback.h"
 #include "supervisor/port.h"
 #include "supervisor/serial.h"
@@ -35,6 +34,10 @@
 #include "lib/utils/interrupt_char.h"
 #include "lib/mp-readline/readline.h"
 
+#if CIRCUITPY_USB_MIDI
+#include "shared-module/usb_midi/__init__.h"
+#endif
+
 #include "tusb.h"
 
 #if CIRCUITPY_USB_VENDOR
@@ -216,7 +219,7 @@ bool tud_vendor_control_xfer_cb(uint8_t rhport, uint8_t stage, tusb_control_requ
 
   return true;
 }
-#endif CIRCUITPY_USB_VENDOR
+#endif // CIRCUITPY_USB_VENDOR
 
 
 #if MICROPY_KBD_EXCEPTION
diff --git a/supervisor/shared/usb/usb_desc.c b/supervisor/shared/usb/usb_desc.c
index 080187ebc..419a70ab3 100644
--- a/supervisor/shared/usb/usb_desc.c
+++ b/supervisor/shared/usb/usb_desc.c
@@ -43,12 +43,14 @@ uint8_t const * tud_descriptor_configuration_cb(uint8_t index) {
     return usb_desc_cfg;
 }
 
+#if CIRCUITPY_USB_HID
 // Invoked when received GET HID REPORT DESCRIPTOR
 // Application return pointer to descriptor
 // Descriptor contents must exist long enough for transfer to complete
 uint8_t const * tud_hid_descriptor_report_cb(void) {
   return hid_report_descriptor;
 }
+#endif
 
 // Invoked when received GET STRING DESCRIPTOR request
 // Application return pointer to descriptor, whose contents must exist long enough for transfer to complete
diff --git a/supervisor/supervisor.mk b/supervisor/supervisor.mk
index f559e004e..374b7a72b 100644
--- a/supervisor/supervisor.mk
+++ b/supervisor/supervisor.mk
@@ -14,23 +14,15 @@ SRC_SUPERVISOR = \
 	supervisor/shared/tick.c \
 	supervisor/shared/translate.c
 
-ifndef $(NO_USB)
-	NO_USB = $(wildcard supervisor/usb.c)
-endif
+NO_USB ?= $(wildcard supervisor/usb.c)
 
-ifndef INTERNAL_FLASH_FILESYSTEM
-INTERNAL_FLASH_FILESYSTEM = 0
-endif
+INTERNAL_FLASH_FILESYSTEM ?= 0
 CFLAGS += -DINTERNAL_FLASH_FILESYSTEM=$(INTERNAL_FLASH_FILESYSTEM)
 
-ifndef QSPI_FLASH_FILESYSTEM
-QSPI_FLASH_FILESYSTEM = 0
-endif
+QSPI_FLASH_FILESYSTEM ?= 0
 CFLAGS += -DQSPI_FLASH_FILESYSTEM=$(QSPI_FLASH_FILESYSTEM)
 
-ifndef SPI_FLASH_FILESYSTEM
-SPI_FLASH_FILESYSTEM = 0
-endif
+SPI_FLASH_FILESYSTEM ?= 0
 CFLAGS += -DSPI_FLASH_FILESYSTEM=$(SPI_FLASH_FILESYSTEM)
 
 ifeq ($(CIRCUITPY_BLEIO),1)
@@ -41,154 +33,180 @@ endif
 # (Right now INTERNAL_FLASH_FILESYSTEM and (Q)SPI_FLASH_FILESYSTEM are mutually exclusive.
 # But that might not be true in the future.)
 ifdef EXTERNAL_FLASH_DEVICES
-	CFLAGS += -DEXTERNAL_FLASH_DEVICES=$(EXTERNAL_FLASH_DEVICES) \
-				-DEXTERNAL_FLASH_DEVICE_COUNT=$(EXTERNAL_FLASH_DEVICE_COUNT)
-
-	SRC_SUPERVISOR += supervisor/shared/external_flash/external_flash.c
-	ifeq ($(SPI_FLASH_FILESYSTEM),1)
-		SRC_SUPERVISOR += supervisor/shared/external_flash/spi_flash.c
-	else
-	endif
-	ifeq ($(QSPI_FLASH_FILESYSTEM),1)
-		SRC_SUPERVISOR += supervisor/qspi_flash.c supervisor/shared/external_flash/qspi_flash.c
-	endif
+  CFLAGS += -DEXTERNAL_FLASH_DEVICES=$(EXTERNAL_FLASH_DEVICES) \
+	    -DEXTERNAL_FLASH_DEVICE_COUNT=$(EXTERNAL_FLASH_DEVICE_COUNT)
+
+  SRC_SUPERVISOR += supervisor/shared/external_flash/external_flash.c
+    ifeq ($(SPI_FLASH_FILESYSTEM),1)
+      SRC_SUPERVISOR += supervisor/shared/external_flash/spi_flash.c
+    endif
+    ifeq ($(QSPI_FLASH_FILESYSTEM),1)
+      SRC_SUPERVISOR += supervisor/qspi_flash.c supervisor/shared/external_flash/qspi_flash.c
+    endif
 else
-	ifeq ($(DISABLE_FILESYSTEM),1)
-		SRC_SUPERVISOR += supervisor/stub/internal_flash.c
-	else
-		SRC_SUPERVISOR += supervisor/internal_flash.c
-	endif
+  ifeq ($(DISABLE_FILESYSTEM),1)
+    SRC_SUPERVISOR += supervisor/stub/internal_flash.c
+  else
+    SRC_SUPERVISOR += supervisor/internal_flash.c
+  endif
 endif
 
 ifeq ($(USB),FALSE)
-	ifeq ($(wildcard supervisor/serial.c),)
-		SRC_SUPERVISOR += supervisor/stub/serial.c
-	else
-		SRC_SUPERVISOR += supervisor/serial.c
-	endif
+  ifeq ($(wildcard supervisor/serial.c),)
+    SRC_SUPERVISOR += supervisor/stub/serial.c
+  else
+    SRC_SUPERVISOR += supervisor/serial.c
+  endif
 else
-	SRC_SUPERVISOR += \
-		lib/tinyusb/src/common/tusb_fifo.c \
-		lib/tinyusb/src/device/usbd.c \
-		lib/tinyusb/src/device/usbd_control.c \
-		lib/tinyusb/src/class/msc/msc_device.c \
-		lib/tinyusb/src/class/cdc/cdc_device.c \
-		lib/tinyusb/src/tusb.c \
-		supervisor/shared/serial.c \
-		supervisor/shared/workflow.c \
-		supervisor/usb.c \
-		supervisor/shared/usb/usb_desc.c \
-		supervisor/shared/usb/usb.c \
-		supervisor/shared/usb/usb_msc_flash.c \
-		$(BUILD)/autogen_usb_descriptor.c
-
-	ifeq ($(CIRCUITPY_USB_HID), 1)
-		SRC_SUPERVISOR += \
-			lib/tinyusb/src/class/hid/hid_device.c \
-			shared-bindings/usb_hid/__init__.c \
-			shared-bindings/usb_hid/Device.c \
-			shared-module/usb_hid/__init__.c \
-			shared-module/usb_hid/Device.c
-	endif
-
-	ifeq ($(CIRCUITPY_USB_MIDI), 1)
-		SRC_SUPERVISOR += \
-			lib/tinyusb/src/class/midi/midi_device.c \
-			shared-bindings/usb_midi/__init__.c \
-			shared-bindings/usb_midi/PortIn.c \
-			shared-bindings/usb_midi/PortOut.c \
-			shared-module/usb_midi/__init__.c \
-			shared-module/usb_midi/PortIn.c \
-			shared-module/usb_midi/PortOut.c
-	endif
-
-	ifeq ($(CIRCUITPY_USB_VENDOR), 1)
-		SRC_SUPERVISOR += \
-			lib/tinyusb/src/class/vendor/vendor_device.c
-	endif
-
-	CFLAGS += -DUSB_AVAILABLE
+  SRC_SUPERVISOR += \
+    lib/tinyusb/src/class/cdc/cdc_device.c \
+    lib/tinyusb/src/common/tusb_fifo.c \
+    lib/tinyusb/src/device/usbd.c \
+    lib/tinyusb/src/device/usbd_control.c \
+    lib/tinyusb/src/tusb.c \
+    supervisor/shared/serial.c \
+    supervisor/shared/workflow.c \
+    supervisor/usb.c \
+    supervisor/shared/usb/usb_desc.c \
+    supervisor/shared/usb/usb.c \
+    $(BUILD)/autogen_usb_descriptor.c \
+
+  ifeq ($(CIRCUITPY_USB_CDC), 1)
+    SRC_SUPERVISOR += \
+      shared-bindings/usb_cdc/__init__.c \
+      shared-bindings/usb_cdc/Serial.c \
+      shared-module/usb_cdc/__init__.c \
+      shared-module/usb_cdc/Serial.c \
+
+  endif
+
+  ifeq ($(CIRCUITPY_USB_HID), 1)
+    SRC_SUPERVISOR += \
+      lib/tinyusb/src/class/hid/hid_device.c \
+      shared-bindings/usb_hid/__init__.c \
+      shared-bindings/usb_hid/Device.c \
+      shared-module/usb_hid/__init__.c \
+      shared-module/usb_hid/Device.c \
+
+  endif
+
+  ifeq ($(CIRCUITPY_USB_MIDI), 1)
+    SRC_SUPERVISOR += \
+      lib/tinyusb/src/class/midi/midi_device.c \
+      shared-bindings/usb_midi/__init__.c \
+      shared-bindings/usb_midi/PortIn.c \
+      shared-bindings/usb_midi/PortOut.c \
+      shared-module/usb_midi/__init__.c \
+      shared-module/usb_midi/PortIn.c \
+      shared-module/usb_midi/PortOut.c \
+
+  endif
+
+  ifeq ($(CIRCUITPY_USB_MSC), 1)
+    SRC_SUPERVISOR += \
+      lib/tinyusb/src/class/msc/msc_device.c \
+      supervisor/shared/usb/usb_msc_flash.c \
+
+  endif
+
+  ifeq ($(CIRCUITPY_USB_VENDOR), 1)
+    SRC_SUPERVISOR += \
+      lib/tinyusb/src/class/vendor/vendor_device.c \
+
+  endif
+
+  CFLAGS += -DUSB_AVAILABLE
 endif
 
 SUPERVISOR_O = $(addprefix $(BUILD)/, $(SRC_SUPERVISOR:.c=.o))
 
 ifeq ($(CIRCUITPY_DISPLAYIO), 1)
-	SRC_SUPERVISOR += \
-		supervisor/shared/display.c
+  SRC_SUPERVISOR += \
+    supervisor/shared/display.c
 
-	ifeq ($(CIRCUITPY_TERMINALIO), 1)
-		SUPERVISOR_O += $(BUILD)/autogen_display_resources.o
-	endif
+  ifeq ($(CIRCUITPY_TERMINALIO), 1)
+    SUPERVISOR_O += $(BUILD)/autogen_display_resources.o
+  endif
 endif
-ifndef USB_INTERFACE_NAME
-USB_INTERFACE_NAME = "CircuitPython"
+
+USB_INTERFACE_NAME ?= "CircuitPython"
+
+ifneq ($(USB_VID),)
+CFLAGS += -DUSB_VID=$(USB_VID)
+CFLAGS += -DSUB_PID=$(USB_PID)
+CFLAGS += -DUSB_MANUFACTURER=$(USB_MANUFACTURER)
+CFLAGS += -DUSB_PRODUCT=$(USB_PRODUCT)
 endif
 
 # In the following URL, don't include the https:// prefix.
 # It gets added automatically.
-ifndef USB_WEBUSB_URL
-USB_WEBUSB_URL = "circuitpython.org"
+USB_WEBUSB_URL ?= "circuitpython.org"
+
+ifeq ($(CIRCUITPY_REPL_USB),1)
+USB_DEVICES += CDC
 endif
 
-USB_DEVICES_COMPUTED := CDC,MSC
+ifeq ($(CIRCUITPY_USB_HID),1)
+USB_DEVICES += HID
+endif
 ifeq ($(CIRCUITPY_USB_MIDI),1)
-USB_DEVICES_COMPUTED := $(USB_DEVICES_COMPUTED),AUDIO
+USB_DEVICES += AUDIO
 endif
-ifeq ($(CIRCUITPY_USB_HID),1)
-USB_DEVICES_COMPUTED := $(USB_DEVICES_COMPUTED),HID
+ifeq ($(CIRCUITPY_USB_MSC),1)
+USB_DEVICES += MSC
 endif
-ifeq ($(CIRCUITPY_USB_VENDOR),1)
-USB_DEVICES_COMPUTED := $(USB_DEVICES_COMPUTED),VENDOR
+ifeq ($(CIRCUITPY_USB_CDC),1)
+# Inform TinyUSB there are two CDC devices.
+CFLAGS += -DCFG_TUD_CDC=2
+USB_DEVICES += CDC2
 endif
-USB_DEVICES ?= "$(USB_DEVICES_COMPUTED)"
-
-ifndef USB_HID_DEVICES
-USB_HID_DEVICES = "KEYBOARD,MOUSE,CONSUMER,GAMEPAD"
+ifeq ($(CIRCUITPY_USB_VENDOR),1)
+USB_DEVICES += VENDOR
 endif
 
-ifndef USB_HIGHSPEED
-USB_HIGHSPEED = 0
+USB_HID_DEVICES =
+ifeq ($(CIRCUITPY_USB_HID_CONSUMER),1)
+USB_HID_DEVICES += CONSUMER
 endif
-
-ifndef USB_CDC_EP_NUM_NOTIFICATION
-USB_CDC_EP_NUM_NOTIFICATION = 0
+ifeq ($(CIRCUITPY_USB_HID_DIGITIZER),1)
+USB_HID_DEVICES += DIGITIZER
 endif
-
-ifndef USB_CDC_EP_NUM_DATA_OUT
-USB_CDC_EP_NUM_DATA_OUT = 0
+ifeq ($(CIRCUITPY_USB_HID_GAMEPAD),1)
+USB_HID_DEVICES += GAMEPAD
 endif
-
-ifndef USB_CDC_EP_NUM_DATA_IN
-USB_CDC_EP_NUM_DATA_IN = 0
+ifeq ($(CIRCUITPY_USB_HID_KEYBOARD),1)
+USB_HID_DEVICES += KEYBOARD
 endif
-
-ifndef USB_MSC_EP_NUM_OUT
-USB_MSC_EP_NUM_OUT = 0
+ifeq ($(CIRCUITPY_USB_HID_MOUSE),1)
+USB_HID_DEVICES += MOUSE
 endif
-
-ifndef USB_MSC_EP_NUM_IN
-USB_MSC_EP_NUM_IN = 0
+ifeq ($(CIRCUITPY_USB_HID_SYS_CONTROL),1)
+USB_HID_DEVICES += SYS_CONTROL
 endif
-
-ifndef USB_HID_EP_NUM_OUT
-USB_HID_EP_NUM_OUT = 0
+ifeq ($(CIRCUITPY_USB_HID_XAC_COMPATIBLE_GAMEPAD),1)
+USB_HID_DEVICES += XAC_COMPATIBLE_GAMEPAD
 endif
 
-ifndef USB_HID_EP_NUM_IN
-USB_HID_EP_NUM_IN = 0
+# RAW is not compatible with other HID devices.
+ifeq ($(CIRCUITPY_USB_HID_RAW),1)
+  ifneq ($(CIRCUITPY_USB_HID_DEVICES,)
+    $(error HID RAW must not be combined with other HID devices)
 endif
-
-ifndef USB_MIDI_EP_NUM_OUT
-USB_MIDI_EP_NUM_OUT = 0
+USB_HID_DEVICES += MOUSE
 endif
 
-ifndef USB_MIDI_EP_NUM_IN
-USB_MIDI_EP_NUM_IN = 0
-endif
+USB_HIGHSPEED ?= 0
 
-ifndef USB_NUM_EP
-USB_NUM_EP = 0
-endif
+USB_CDC_EP_NUM_NOTIFICATION ?= 0
+USB_CDC_EP_NUM_DATA_OUT ?= 0
+USB_CDC_EP_NUM_DATA_IN ?= 0
+USB_MSC_EP_NUM_OUT ?= 0
+USB_MSC_EP_NUM_IN ?= 0
+USB_HID_EP_NUM_OUT ?= 0
+USB_HID_EP_NUM_IN ?= 0
+USB_MIDI_EP_NUM_OUT ?= 0
+USB_MIDI_EP_NUM_IN ?= 0
+USB_NUM_EP ?= 0
 
 USB_DESCRIPTOR_ARGS = \
 	--manufacturer $(USB_MANUFACTURER)\
@@ -197,8 +215,8 @@ USB_DESCRIPTOR_ARGS = \
 	--pid $(USB_PID)\
 	--serial_number_length $(USB_SERIAL_NUMBER_LENGTH)\
 	--interface_name $(USB_INTERFACE_NAME)\
-	--devices $(USB_DEVICES)\
-	--hid_devices $(USB_HID_DEVICES)\
+	--devices "$(USB_DEVICES)"\
+	--hid_devices "$(USB_HID_DEVICES)"\
 	--max_ep $(USB_NUM_EP) \
 	--cdc_ep_num_notification $(USB_CDC_EP_NUM_NOTIFICATION)\
 	--cdc_ep_num_data_out $(USB_CDC_EP_NUM_DATA_OUT)\
diff --git a/tools/gen_usb_descriptor.py b/tools/gen_usb_descriptor.py
index 80dddeb00..089d00ff2 100644
--- a/tools/gen_usb_descriptor.py
+++ b/tools/gen_usb_descriptor.py
@@ -12,70 +12,130 @@ sys.path.append("../../tools/usb_descriptor")
 from adafruit_usb_descriptor import audio, audio10, cdc, hid, midi, msc, standard, util
 import hid_report_descriptors
 
-DEFAULT_INTERFACE_NAME = 'CircuitPython'
-ALL_DEVICES='CDC,MSC,AUDIO,HID,VENDOR'
-ALL_DEVICES_SET=frozenset(ALL_DEVICES.split(','))
-DEFAULT_DEVICES='CDC,MSC,AUDIO,HID'
-
-ALL_HID_DEVICES='KEYBOARD,MOUSE,CONSUMER,SYS_CONTROL,GAMEPAD,DIGITIZER,XAC_COMPATIBLE_GAMEPAD,RAW'
-ALL_HID_DEVICES_SET=frozenset(ALL_HID_DEVICES.split(','))
+DEFAULT_INTERFACE_NAME = "CircuitPython"
+ALL_DEVICES = "CDC CDC2 MSC AUDIO HID VENDOR"
+ALL_DEVICES_SET = frozenset(ALL_DEVICES.split())
+DEFAULT_DEVICES = "CDC MSC AUDIO HID"
+
+ALL_HID_DEVICES = (
+    "KEYBOARD MOUSE CONSUMER SYS_CONTROL GAMEPAD DIGITIZER XAC_COMPATIBLE_GAMEPAD RAW"
+)
+ALL_HID_DEVICES_SET = frozenset(ALL_HID_DEVICES.split())
 # Digitizer works on Linux but conflicts with mouse, so omit it.
-DEFAULT_HID_DEVICES='KEYBOARD,MOUSE,CONSUMER,GAMEPAD'
+DEFAULT_HID_DEVICES = "KEYBOARD MOUSE CONSUMER GAMEPAD"
 
 # In the following URL, don't include the https:// because that prefix gets added automatically
-DEFAULT_WEBUSB_URL = 'circuitpython.org' # In the future, this may become a specific landing page
-
-parser = argparse.ArgumentParser(description='Generate USB descriptors.')
-parser.add_argument('--highspeed', default=False, action='store_true',
-                    help='descriptor for highspeed device')
-parser.add_argument('--manufacturer', type=str,
-                    help='manufacturer of the device')
-parser.add_argument('--product', type=str,
-                    help='product name of the device')
-parser.add_argument('--vid', type=lambda x: int(x, 16),
-                    help='vendor id')
-parser.add_argument('--pid', type=lambda x: int(x, 16),
-                    help='product id')
-parser.add_argument('--serial_number_length', type=int, default=32,
-                    help='length needed for the serial number in digits')
-parser.add_argument('--devices', type=lambda l: tuple(l.split(',')), default=DEFAULT_DEVICES,
-                    help='devices to include in descriptor (AUDIO includes MIDI support)')
-parser.add_argument('--hid_devices', type=lambda l: tuple(l.split(',')), default=DEFAULT_HID_DEVICES,
-                    help='HID devices to include in HID report descriptor')
-parser.add_argument('--interface_name', type=str,
-                    help='The name/prefix to use in the interface descriptions',
-                    default=DEFAULT_INTERFACE_NAME)
-parser.add_argument('--no-renumber_endpoints', dest='renumber_endpoints', action='store_false',
-                    help='use to not renumber endpoint')
-parser.add_argument('--cdc_ep_num_notification', type=int, default=0,
-                    help='endpoint number of CDC NOTIFICATION')
-parser.add_argument('--cdc_ep_num_data_out', type=int, default=0,
-                    help='endpoint number of CDC DATA OUT')
-parser.add_argument('--cdc_ep_num_data_in', type=int, default=0,
-                    help='endpoint number of CDC DATA IN')
-parser.add_argument('--msc_ep_num_out', type=int, default=0,
-                    help='endpoint number of MSC OUT')
-parser.add_argument('--msc_ep_num_in', type=int, default=0,
-                    help='endpoint number of MSC IN')
-parser.add_argument('--hid_ep_num_out', type=int, default=0,
-                    help='endpoint number of HID OUT')
-parser.add_argument('--hid_ep_num_in', type=int, default=0,
-                    help='endpoint number of HID IN')
-parser.add_argument('--midi_ep_num_out', type=int, default=0,
-                    help='endpoint number of MIDI OUT')
-parser.add_argument('--midi_ep_num_in', type=int, default=0,
-                    help='endpoint number of MIDI IN')
-parser.add_argument('--webusb_url', type=str,
-                    help='The URL to include in the WebUSB URL Descriptor',
-                    default=DEFAULT_WEBUSB_URL)
-parser.add_argument('--vendor_ep_num_out', type=int, default=0,
-                    help='endpoint number of VENDOR OUT')
-parser.add_argument('--vendor_ep_num_in', type=int, default=0,
-                    help='endpoint number of VENDOR IN')
-parser.add_argument('--max_ep', type=int, default=0,
-                    help='total number of endpoints available')
-parser.add_argument('--output_c_file', type=argparse.FileType('w', encoding='UTF-8'), required=True)
-parser.add_argument('--output_h_file', type=argparse.FileType('w', encoding='UTF-8'), required=True)
+DEFAULT_WEBUSB_URL = (
+    "circuitpython.org"  # In the future, this may become a specific landing page
+)
+
+parser = argparse.ArgumentParser(description="Generate USB descriptors.")
+parser.add_argument(
+    "--highspeed",
+    default=False,
+    action="store_true",
+    help="descriptor for highspeed device",
+)
+parser.add_argument("--manufacturer", type=str, help="manufacturer of the device")
+parser.add_argument("--product", type=str, help="product name of the device")
+parser.add_argument("--vid", type=lambda x: int(x, 16), help="vendor id")
+parser.add_argument("--pid", type=lambda x: int(x, 16), help="product id")
+parser.add_argument(
+    "--serial_number_length",
+    type=int,
+    default=32,
+    help="length needed for the serial number in digits",
+)
+parser.add_argument(
+    "--devices",
+    type=lambda l: tuple(l.split()),
+    default=DEFAULT_DEVICES,
+    help="devices to include in descriptor (AUDIO includes MIDI support)",
+)
+parser.add_argument(
+    "--hid_devices",
+    type=lambda l: tuple(l.split()),
+    default=DEFAULT_HID_DEVICES,
+    help="HID devices to include in HID report descriptor",
+)
+parser.add_argument(
+    "--interface_name",
+    type=str,
+    help="The name/prefix to use in the interface descriptions",
+    default=DEFAULT_INTERFACE_NAME,
+)
+parser.add_argument(
+    "--no-renumber_endpoints",
+    dest="renumber_endpoints",
+    action="store_false",
+    help="use to not renumber endpoint",
+)
+parser.add_argument(
+    "--cdc_ep_num_notification",
+    type=int,
+    default=0,
+    help="endpoint number of CDC NOTIFICATION",
+)
+parser.add_argument(
+    "--cdc2_ep_num_notification",
+    type=int,
+    default=0,
+    help="endpoint number of CDC2 NOTIFICATION",
+)
+parser.add_argument(
+    "--cdc_ep_num_data_out", type=int, default=0, help="endpoint number of CDC DATA OUT"
+)
+parser.add_argument(
+    "--cdc_ep_num_data_in", type=int, default=0, help="endpoint number of CDC DATA IN"
+)
+parser.add_argument(
+    "--cdc2_ep_num_data_out",
+    type=int,
+    default=0,
+    help="endpoint number of CDC2 DATA OUT",
+)
+parser.add_argument(
+    "--cdc2_ep_num_data_in", type=int, default=0, help="endpoint number of CDC2 DATA IN"
+)
+parser.add_argument(
+    "--msc_ep_num_out", type=int, default=0, help="endpoint number of MSC OUT"
+)
+parser.add_argument(
+    "--msc_ep_num_in", type=int, default=0, help="endpoint number of MSC IN"
+)
+parser.add_argument(
+    "--hid_ep_num_out", type=int, default=0, help="endpoint number of HID OUT"
+)
+parser.add_argument(
+    "--hid_ep_num_in", type=int, default=0, help="endpoint number of HID IN"
+)
+parser.add_argument(
+    "--midi_ep_num_out", type=int, default=0, help="endpoint number of MIDI OUT"
+)
+parser.add_argument(
+    "--midi_ep_num_in", type=int, default=0, help="endpoint number of MIDI IN"
+)
+parser.add_argument(
+    "--max_ep", type=int, default=0, help="total number of endpoints available"
+)
+parser.add_argument(
+    "--webusb_url",
+    type=str,
+    help="The URL to include in the WebUSB URL Descriptor",
+    default=DEFAULT_WEBUSB_URL,
+)
+parser.add_argument(
+    "--vendor_ep_num_out", type=int, default=0, help="endpoint number of VENDOR OUT"
+)
+parser.add_argument(
+    "--vendor_ep_num_in", type=int, default=0, help="endpoint number of VENDOR IN"
+)
+parser.add_argument(
+    "--output_c_file", type=argparse.FileType("w", encoding="UTF-8"), required=True
+)
+parser.add_argument(
+    "--output_h_file", type=argparse.FileType("w", encoding="UTF-8"), required=True
+)
 
 args = parser.parse_args()
 
@@ -87,47 +147,67 @@ unknown_hid_devices = list(frozenset(args.hid_devices) - ALL_HID_DEVICES_SET)
 if unknown_hid_devices:
     raise ValueError("Unknown HID devices(s)", unknown_hid_devices)
 
+include_cdc = "CDC" in args.devices
+include_cdc2 = "CDC2" in args.devices
+include_msc = "MSC" in args.devices
+include_hid = "HID" in args.devices
+include_audio = "AUDIO" in args.devices
+include_vendor = "VENDOR" in args.devices
+
+if not include_cdc and include_cdc2:
+    raise ValueError("CDC2 requested without CDC")
+
 if not args.renumber_endpoints:
-    if 'CDC' in args.devices:
+    if include_cdc:
         if args.cdc_ep_num_notification == 0:
             raise ValueError("CDC notification endpoint number must not be 0")
-        elif args.cdc_ep_num_data_out == 0:
+        if args.cdc_ep_num_data_out == 0:
             raise ValueError("CDC data OUT endpoint number must not be 0")
-        elif args.cdc_ep_num_data_in == 0:
+        if args.cdc_ep_num_data_in == 0:
             raise ValueError("CDC data IN endpoint number must not be 0")
 
-    if 'MSC' in args.devices:
+    if include_cdc2:
+        if args.cdc2_ep_num_notification == 0:
+            raise ValueError("CDC2 notification endpoint number must not be 0")
+        if args.cdc2_ep_num_data_out == 0:
+            raise ValueError("CDC2 data OUT endpoint number must not be 0")
+        if args.cdc2_ep_num_data_in == 0:
+            raise ValueError("CDC2 data IN endpoint number must not be 0")
+
+    if include_msc:
         if args.msc_ep_num_out == 0:
             raise ValueError("MSC endpoint OUT number must not be 0")
-        elif args.msc_ep_num_in == 0:
+        if args.msc_ep_num_in == 0:
             raise ValueError("MSC endpoint IN number must not be 0")
 
-    if 'HID' in args.devices:
+    if include_hid:
         if args.args.hid_ep_num_out == 0:
             raise ValueError("HID endpoint OUT number must not be 0")
-        elif args.hid_ep_num_in == 0:
+        if args.hid_ep_num_in == 0:
             raise ValueError("HID endpoint IN number must not be 0")
 
-    if 'AUDIO' in args.devices:
+    if include_audio:
         if args.args.midi_ep_num_out == 0:
             raise ValueError("MIDI endpoint OUT number must not be 0")
-        elif args.midi_ep_num_in == 0:
+        if args.midi_ep_num_in == 0:
             raise ValueError("MIDI endpoint IN number must not be 0")
 
-    if 'VENDOR' in args.devices:
+    if include_vendor:
         if args.vendor_ep_num_out == 0:
             raise ValueError("VENDOR endpoint OUT number must not be 0")
-        elif args.vendor_ep_num_in == 0:
+        if args.vendor_ep_num_in == 0:
             raise ValueError("VENDOR endpoint IN number must not be 0")
 
+
 class StringIndex:
     """Assign a monotonically increasing index to each unique string. Start with 0."""
+
     string_to_index = {}
     index_to_variable = {}
     strings = []
 
     @classmethod
-    def index(cls, string, *, variable_name = None):
+    def index(cls, string, *, variable_name=None):
         if string in cls.string_to_index:
             idx = cls.string_to_index[string]
             if not cls.index_to_variable[idx]:
@@ -145,11 +225,12 @@ class StringIndex:
         return cls.strings
 
 
-
 # langid must be the 0th string descriptor
 LANGID_INDEX = StringIndex.index("\u0409", variable_name="language_id")
 assert LANGID_INDEX == 0
-SERIAL_NUMBER_INDEX = StringIndex.index("S" * args.serial_number_length, variable_name="usb_serial_number")
+SERIAL_NUMBER_INDEX = StringIndex.index(
+    "S" * args.serial_number_length, variable_name="usb_serial_number"
+)
 
 device = standard.DeviceDescriptor(
     description="top",
@@ -157,212 +238,279 @@ device = standard.DeviceDescriptor(
     idProduct=args.pid,
     iManufacturer=StringIndex.index(args.manufacturer),
     iProduct=StringIndex.index(args.product),
-    iSerialNumber=SERIAL_NUMBER_INDEX)
+    iSerialNumber=SERIAL_NUMBER_INDEX,
+)
 
 # Interface numbers are interface-set local and endpoints are interface local
 # until util.join_interfaces renumbers them.
 
-cdc_union = cdc.Union(
-    description="CDC comm",
-    bMasterInterface=0x00,       # Adjust this after interfaces are renumbered.
-    bSlaveInterface_list=[0x01]) # Adjust this after interfaces are renumbered.
-
-cdc_call_management = cdc.CallManagement(
-    description="CDC comm",
-    bmCapabilities=0x01,
-    bDataInterface=0x01)         # Adjust this after interfaces are renumbered.
-
-cdc_comm_interface = standard.InterfaceDescriptor(
-    description="CDC comm",
-    bInterfaceClass=cdc.CDC_CLASS_COMM,  # Communications Device Class
-    bInterfaceSubClass=cdc.CDC_SUBCLASS_ACM,  # Abstract control model
-    bInterfaceProtocol=cdc.CDC_PROTOCOL_NONE,
-    iInterface=StringIndex.index("{} CDC control".format(args.interface_name)),
-    subdescriptors=[
-        cdc.Header(
-            description="CDC comm",
-            bcdCDC=0x0110),
-        cdc_call_management,
-        cdc.AbstractControlManagement(
-            description="CDC comm",
-            bmCapabilities=0x02),
-        cdc_union,
-        standard.EndpointDescriptor(
-            description="CDC comm in",
-            bEndpointAddress=args.cdc_ep_num_notification | standard.EndpointDescriptor.DIRECTION_IN,
-            bmAttributes=standard.EndpointDescriptor.TYPE_INTERRUPT,
-            wMaxPacketSize=0x0040,
-            bInterval=0x10)
-    ])
-
-cdc_data_interface = standard.InterfaceDescriptor(
-    description="CDC data",
-    bInterfaceClass=cdc.CDC_CLASS_DATA,
-    iInterface=StringIndex.index("{} CDC data".format(args.interface_name)),
-    subdescriptors=[
-        standard.EndpointDescriptor(
-            description="CDC data out",
-            bEndpointAddress=args.cdc_ep_num_data_out | standard.EndpointDescriptor.DIRECTION_OUT,
-            bmAttributes=standard.EndpointDescriptor.TYPE_BULK,
-            bInterval=0,
-            wMaxPacketSize=512 if args.highspeed else 64),
-        standard.EndpointDescriptor(
-            description="CDC data in",
-            bEndpointAddress=args.cdc_ep_num_data_in | standard.EndpointDescriptor.DIRECTION_IN,
-            bmAttributes=standard.EndpointDescriptor.TYPE_BULK,
-            bInterval=0,
-            wMaxPacketSize=512 if args.highspeed else 64),
-    ])
-
-cdc_interfaces = [cdc_comm_interface, cdc_data_interface]
-
-msc_interfaces = [
-    standard.InterfaceDescriptor(
-        description="MSC",
-        bInterfaceClass=msc.MSC_CLASS,
-        bInterfaceSubClass=msc.MSC_SUBCLASS_TRANSPARENT,
-        bInterfaceProtocol=msc.MSC_PROTOCOL_BULK,
-        iInterface=StringIndex.index("{} Mass Storage".format(args.interface_name)),
+
+def make_cdc_union(name):
+    return cdc.Union(
+        description="{} comm".format(name),
+        # Set bMasterInterface and bSlaveInterface_list to proper values after interfaces are renumbered.
+        bMasterInterface=0x00,
+        bSlaveInterface_list=[0x01],
+    )
+
+
+def make_cdc_call_management(name):
+    # Set bDataInterface to proper value after interfaces are renumbered.
+    return cdc.CallManagement(
+        description="{} comm".format(name), bmCapabilities=0x01, bDataInterface=0x01
+    )
+
+
+def make_cdc_comm_interface(
+    name, cdc_union, cdc_call_management, cdc_ep_num_notification
+):
+    return standard.InterfaceDescriptor(
+        description="{} comm".format(name),
+        bInterfaceClass=cdc.CDC_CLASS_COMM,  # Communications Device Class
+        bInterfaceSubClass=cdc.CDC_SUBCLASS_ACM,  # Abstract control model
+        bInterfaceProtocol=cdc.CDC_PROTOCOL_NONE,
+        iInterface=StringIndex.index("{} {} control".format(args.interface_name, name)),
+        subdescriptors=[
+            cdc.Header(description="{} comm".format(name), bcdCDC=0x0110),
+            cdc_call_management,
+            cdc.AbstractControlManagement(
+                description="{} comm".format(name), bmCapabilities=0x02
+            ),
+            cdc_union,
+            standard.EndpointDescriptor(
+                description="{} comm in".format(name),
+                bEndpointAddress=cdc_ep_num_notification
+                | standard.EndpointDescriptor.DIRECTION_IN,
+                bmAttributes=standard.EndpointDescriptor.TYPE_INTERRUPT,
+                wMaxPacketSize=0x0040,
+                bInterval=0x10,
+            ),
+        ],
+    )
+
+
+def make_cdc_data_interface(name, cdc_ep_num_data_in, cdc_ep_num_data_out):
+    return standard.InterfaceDescriptor(
+        description="{} data".format(name),
+        bInterfaceClass=cdc.CDC_CLASS_DATA,
+        iInterface=StringIndex.index("{} {} data".format(args.interface_name, name)),
         subdescriptors=[
             standard.EndpointDescriptor(
-                description="MSC in",
-                bEndpointAddress=args.msc_ep_num_in | standard.EndpointDescriptor.DIRECTION_IN,
+                description="{} data out".format(name),
+                bEndpointAddress=cdc_ep_num_data_out
+                | standard.EndpointDescriptor.DIRECTION_OUT,
                 bmAttributes=standard.EndpointDescriptor.TYPE_BULK,
                 bInterval=0,
-                wMaxPacketSize=512 if args.highspeed else 64),
+                wMaxPacketSize=512 if args.highspeed else 64,
+            ),
             standard.EndpointDescriptor(
-                description="MSC out",
-                bEndpointAddress=(args.msc_ep_num_out | standard.EndpointDescriptor.DIRECTION_OUT),
+                description="{} data in".format(name),
+                bEndpointAddress=cdc_ep_num_data_in
+                | standard.EndpointDescriptor.DIRECTION_IN,
                 bmAttributes=standard.EndpointDescriptor.TYPE_BULK,
                 bInterval=0,
-                wMaxPacketSize=512 if args.highspeed else 64),
-        ]
+                wMaxPacketSize=512 if args.highspeed else 64,
+            ),
+        ],
     )
-]
 
-# When there's only one hid_device, it shouldn't have a report id.
-# Otherwise, report ids are assigned sequentially:
-# args.hid_devices[0] has report_id 1
-# args.hid_devices[1] has report_id 2
-# etc.
 
-report_ids = {}
+if include_cdc:
+    cdc_union = make_cdc_union("CDC")
+    cdc_call_management = make_cdc_call_management("CDC")
+    cdc_comm_interface = make_cdc_comm_interface(
+        "CDC", cdc_union, cdc_call_management, args.cdc_ep_num_notification
+    )
+    cdc_data_interface = make_cdc_data_interface(
+        "CDC", args.cdc_ep_num_data_in, args.cdc_ep_num_data_out
+    )
 
-if len(args.hid_devices) == 1:
-    name = args.hid_devices[0]
-    combined_hid_report_descriptor = hid.ReportDescriptor(
-        description=name,
-        report_descriptor=bytes(hid_report_descriptors.REPORT_DESCRIPTOR_FUNCTIONS[name](0)))
-    report_ids[name] = 0
-else:
-    report_id = 1
-    concatenated_descriptors = bytearray()
-    for name in args.hid_devices:
-        concatenated_descriptors.extend(
-            bytes(hid_report_descriptors.REPORT_DESCRIPTOR_FUNCTIONS[name](report_id)))
-        report_ids[name] = report_id
-        report_id += 1
-    combined_hid_report_descriptor = hid.ReportDescriptor(
-        description="MULTIDEVICE",
-        report_descriptor=bytes(concatenated_descriptors))
-
-# ASF4 expects keyboard and generic devices to have both in and out endpoints,
-# and will fail (possibly silently) if both are not supplied.
-hid_endpoint_in_descriptor = standard.EndpointDescriptor(
-    description="HID in",
-    bEndpointAddress=args.hid_ep_num_in | standard.EndpointDescriptor.DIRECTION_IN,
-    bmAttributes=standard.EndpointDescriptor.TYPE_INTERRUPT,
-    bInterval=8)
-
-hid_endpoint_out_descriptor = standard.EndpointDescriptor(
-    description="HID out",
-    bEndpointAddress=args.hid_ep_num_out | standard.EndpointDescriptor.DIRECTION_OUT,
-    bmAttributes=standard.EndpointDescriptor.TYPE_INTERRUPT,
-    bInterval=8)
-
-hid_interfaces = [
-    standard.InterfaceDescriptor(
-        description="HID Multiple Devices",
-        bInterfaceClass=hid.HID_CLASS,
-        bInterfaceSubClass=hid.HID_SUBCLASS_NOBOOT,
-        bInterfaceProtocol=hid.HID_PROTOCOL_NONE,
-        iInterface=StringIndex.index("{} HID".format(args.interface_name)),
-        subdescriptors=[
-            hid.HIDDescriptor(
-                description="HID",
-                wDescriptorLength=len(bytes(combined_hid_report_descriptor))),
-            hid_endpoint_in_descriptor,
-            hid_endpoint_out_descriptor,
-            ]
-        ),
+    cdc_interfaces = [cdc_comm_interface, cdc_data_interface]
+
+if include_cdc2:
+    cdc2_union = make_cdc_union("CDC2")
+    cdc2_call_management = make_cdc_call_management("CDC2")
+    cdc2_comm_interface = make_cdc_comm_interface(
+        "CDC2", cdc2_union, cdc2_call_management, args.cdc2_ep_num_notification
+    )
+    cdc2_data_interface = make_cdc_data_interface(
+        "CDC2", args.cdc2_ep_num_data_in, args.cdc2_ep_num_data_out
+    )
+
+    cdc2_interfaces = [cdc2_comm_interface, cdc2_data_interface]
+
+if include_msc:
+    msc_interfaces = [
+        standard.InterfaceDescriptor(
+            description="MSC",
+            bInterfaceClass=msc.MSC_CLASS,
+            bInterfaceSubClass=msc.MSC_SUBCLASS_TRANSPARENT,
+            bInterfaceProtocol=msc.MSC_PROTOCOL_BULK,
+            iInterface=StringIndex.index("{} Mass Storage".format(args.interface_name)),
+            subdescriptors=[
+                standard.EndpointDescriptor(
+                    description="MSC in",
+                    bEndpointAddress=args.msc_ep_num_in
+                    | standard.EndpointDescriptor.DIRECTION_IN,
+                    bmAttributes=standard.EndpointDescriptor.TYPE_BULK,
+                    bInterval=0,
+                    wMaxPacketSize=512 if args.highspeed else 64,
+                ),
+                standard.EndpointDescriptor(
+                    description="MSC out",
+                    bEndpointAddress=(
+                        args.msc_ep_num_out | standard.EndpointDescriptor.DIRECTION_OUT
+                    ),
+                    bmAttributes=standard.EndpointDescriptor.TYPE_BULK,
+                    bInterval=0,
+                    wMaxPacketSize=512 if args.highspeed else 64,
+                ),
+            ],
+        )
     ]
 
-# Audio!
-# In and out here are relative to CircuitPython
-
-# USB OUT -> midi_in_jack_emb -> midi_out_jack_ext -> CircuitPython
-midi_in_jack_emb = midi.InJackDescriptor(
-    description="MIDI PC -> {}".format(args.interface_name),
-    bJackType=midi.JACK_TYPE_EMBEDDED,
-    iJack=StringIndex.index("{} usb_midi.ports[0]".format(args.interface_name)))
-midi_out_jack_ext = midi.OutJackDescriptor(
-                    description="MIDI data out to user code.",
-                    bJackType=midi.JACK_TYPE_EXTERNAL,
-                    input_pins=[(midi_in_jack_emb, 1)],
-                    iJack=0)
-
-# USB IN <- midi_out_jack_emb <- midi_in_jack_ext <- CircuitPython
-midi_in_jack_ext = midi.InJackDescriptor(
-                    description="MIDI data in from user code.",
-                    bJackType=midi.JACK_TYPE_EXTERNAL,
-                    iJack=0)
-midi_out_jack_emb = midi.OutJackDescriptor(
-    description="MIDI PC <- {}".format(args.interface_name),
-    bJackType=midi.JACK_TYPE_EMBEDDED,
-    input_pins=[(midi_in_jack_ext, 1)],
-    iJack=StringIndex.index("{} usb_midi.ports[1]".format(args.interface_name)))
-
-
-audio_midi_interface = standard.InterfaceDescriptor(
-    description="Midi goodness",
-    bInterfaceClass=audio.AUDIO_CLASS_DEVICE,
-    bInterfaceSubClass=audio.AUDIO_SUBCLASS_MIDI_STREAMING,
-    bInterfaceProtocol=audio.AUDIO_PROTOCOL_V1,
-    iInterface=StringIndex.index("{} MIDI".format(args.interface_name)),
-    subdescriptors=[
-        midi.Header(
-            jacks_and_elements=[
-                midi_in_jack_emb,
-                midi_in_jack_ext,
-                midi_out_jack_emb,
-                midi_out_jack_ext
+
+if include_hid:
+    # When there's only one hid_device, it shouldn't have a report id.
+    # Otherwise, report ids are assigned sequentially:
+    # args.hid_devices[0] has report_id 1
+    # args.hid_devices[1] has report_id 2
+    # etc.
+
+    report_ids = {}
+
+    if len(args.hid_devices) == 1:
+        name = args.hid_devices[0]
+        combined_hid_report_descriptor = hid.ReportDescriptor(
+            description=name,
+            report_descriptor=bytes(
+                hid_report_descriptors.REPORT_DESCRIPTOR_FUNCTIONS[name](0)
+            ),
+        )
+        report_ids[name] = 0
+    else:
+        report_id = 1
+        concatenated_descriptors = bytearray()
+        for name in args.hid_devices:
+            concatenated_descriptors.extend(
+                bytes(
+                    hid_report_descriptors.REPORT_DESCRIPTOR_FUNCTIONS[name](report_id)
+                )
+            )
+            report_ids[name] = report_id
+            report_id += 1
+        combined_hid_report_descriptor = hid.ReportDescriptor(
+            description="MULTIDEVICE", report_descriptor=bytes(concatenated_descriptors)
+        )
+
+    # ASF4 expects keyboard and generic devices to have both in and out endpoints,
+    # and will fail (possibly silently) if both are not supplied.
+    hid_endpoint_in_descriptor = standard.EndpointDescriptor(
+        description="HID in",
+        bEndpointAddress=args.hid_ep_num_in | standard.EndpointDescriptor.DIRECTION_IN,
+        bmAttributes=standard.EndpointDescriptor.TYPE_INTERRUPT,
+        bInterval=8,
+    )
+
+    hid_endpoint_out_descriptor = standard.EndpointDescriptor(
+        description="HID out",
+        bEndpointAddress=args.hid_ep_num_out
+        | standard.EndpointDescriptor.DIRECTION_OUT,
+        bmAttributes=standard.EndpointDescriptor.TYPE_INTERRUPT,
+        bInterval=8,
+    )
+
+    hid_interfaces = [
+        standard.InterfaceDescriptor(
+            description="HID Multiple Devices",
+            bInterfaceClass=hid.HID_CLASS,
+            bInterfaceSubClass=hid.HID_SUBCLASS_NOBOOT,
+            bInterfaceProtocol=hid.HID_PROTOCOL_NONE,
+            iInterface=StringIndex.index("{} HID".format(args.interface_name)),
+            subdescriptors=[
+                hid.HIDDescriptor(
+                    description="HID",
+                    wDescriptorLength=len(bytes(combined_hid_report_descriptor)),
+                ),
+                hid_endpoint_in_descriptor,
+                hid_endpoint_out_descriptor,
             ],
         ),
-        standard.EndpointDescriptor(
-            description="MIDI data out to {}".format(args.interface_name),
-            bEndpointAddress=args.midi_ep_num_out | standard.EndpointDescriptor.DIRECTION_OUT,
-            bmAttributes=standard.EndpointDescriptor.TYPE_BULK,
-            bInterval=0,
-            wMaxPacketSize=512 if args.highspeed else 64),
-        midi.DataEndpointDescriptor(baAssocJack=[midi_in_jack_emb]),
-        standard.EndpointDescriptor(
-            description="MIDI data in from {}".format(args.interface_name),
-            bEndpointAddress=args.midi_ep_num_in | standard.EndpointDescriptor.DIRECTION_IN,
-            bmAttributes=standard.EndpointDescriptor.TYPE_BULK,
-            bInterval = 0x0,
-            wMaxPacketSize=512 if args.highspeed else 64),
-        midi.DataEndpointDescriptor(baAssocJack=[midi_out_jack_emb]),
-    ])
-
-cs_ac_interface = audio10.AudioControlInterface(
+    ]
+
+if include_audio:
+    # Audio!
+    # In and out here are relative to CircuitPython
+
+    # USB OUT -> midi_in_jack_emb -> midi_out_jack_ext -> CircuitPython
+    midi_in_jack_emb = midi.InJackDescriptor(
+        description="MIDI PC -> {}".format(args.interface_name),
+        bJackType=midi.JACK_TYPE_EMBEDDED,
+        iJack=StringIndex.index("{} usb_midi.ports[0]".format(args.interface_name)),
+    )
+    midi_out_jack_ext = midi.OutJackDescriptor(
+        description="MIDI data out to user code.",
+        bJackType=midi.JACK_TYPE_EXTERNAL,
+        input_pins=[(midi_in_jack_emb, 1)],
+        iJack=0,
+    )
+
+    # USB IN <- midi_out_jack_emb <- midi_in_jack_ext <- CircuitPython
+    midi_in_jack_ext = midi.InJackDescriptor(
+        description="MIDI data in from user code.",
+        bJackType=midi.JACK_TYPE_EXTERNAL,
+        iJack=0,
+    )
+    midi_out_jack_emb = midi.OutJackDescriptor(
+        description="MIDI PC <- {}".format(args.interface_name),
+        bJackType=midi.JACK_TYPE_EMBEDDED,
+        input_pins=[(midi_in_jack_ext, 1)],
+        iJack=StringIndex.index("{} usb_midi.ports[1]".format(args.interface_name)),
+    )
+
+    audio_midi_interface = standard.InterfaceDescriptor(
+        description="Midi goodness",
+        bInterfaceClass=audio.AUDIO_CLASS_DEVICE,
+        bInterfaceSubClass=audio.AUDIO_SUBCLASS_MIDI_STREAMING,
+        bInterfaceProtocol=audio.AUDIO_PROTOCOL_V1,
+        iInterface=StringIndex.index("{} MIDI".format(args.interface_name)),
+        subdescriptors=[
+            midi.Header(
+                jacks_and_elements=[
+                    midi_in_jack_emb,
+                    midi_in_jack_ext,
+                    midi_out_jack_emb,
+                    midi_out_jack_ext,
+                ],
+            ),
+            standard.EndpointDescriptor(
+                description="MIDI data out to {}".format(args.interface_name),
+                bEndpointAddress=args.midi_ep_num_out
+                | standard.EndpointDescriptor.DIRECTION_OUT,
+                bmAttributes=standard.EndpointDescriptor.TYPE_BULK,
+                bInterval=0,
+                wMaxPacketSize=512 if args.highspeed else 64,
+            ),
+            midi.DataEndpointDescriptor(baAssocJack=[midi_in_jack_emb]),
+            standard.EndpointDescriptor(
+                description="MIDI data in from {}".format(args.interface_name),
+                bEndpointAddress=args.midi_ep_num_in
+                | standard.EndpointDescriptor.DIRECTION_IN,
+                bmAttributes=standard.EndpointDescriptor.TYPE_BULK,
+                bInterval=0x0,
+                wMaxPacketSize=512 if args.highspeed else 64,
+            ),
+            midi.DataEndpointDescriptor(baAssocJack=[midi_out_jack_emb]),
+        ],
+    )
+
+    cs_ac_interface = audio10.AudioControlInterface(
         description="Empty audio control",
-        audio_streaming_interfaces = [],
-        midi_streaming_interfaces = [
-            audio_midi_interface
-        ]
+        audio_streaming_interfaces=[],
+        midi_streaming_interfaces=[audio_midi_interface],
     )
 
-audio_control_interface = standard.InterfaceDescriptor(
+    audio_control_interface = standard.InterfaceDescriptor(
         description="All the audio",
         bInterfaceClass=audio.AUDIO_CLASS_DEVICE,
         bInterfaceSubClass=audio.AUDIO_SUBCLASS_CONTROL,
@@ -370,89 +518,124 @@ audio_control_interface = standard.InterfaceDescriptor(
         iInterface=StringIndex.index("{} Audio".format(args.interface_name)),
         subdescriptors=[
             cs_ac_interface,
-        ])
-
-# Audio streaming interfaces must occur before MIDI ones.
-audio_interfaces = [audio_control_interface] + cs_ac_interface.audio_streaming_interfaces + cs_ac_interface.midi_streaming_interfaces
-
-# Vendor-specific interface, for example WebUSB
-vendor_endpoint_in_descriptor = standard.EndpointDescriptor(
-    description="VENDOR in",
-    bEndpointAddress=args.vendor_ep_num_in | standard.EndpointDescriptor.DIRECTION_IN,
-    bmAttributes=standard.EndpointDescriptor.TYPE_BULK,
-    bInterval=16)
-
-vendor_endpoint_out_descriptor = standard.EndpointDescriptor(
-    description="VENDOR out",
-    bEndpointAddress=args.vendor_ep_num_out | standard.EndpointDescriptor.DIRECTION_OUT,
-    bmAttributes=standard.EndpointDescriptor.TYPE_BULK,
-    bInterval=16)
-
-# We do the following conditionally to avoid adding unused entries to the StringIndex table
-if 'VENDOR' in args.devices:
+        ],
+    )
+
+    # Audio streaming interfaces must occur before MIDI ones.
+    audio_interfaces = (
+        [audio_control_interface]
+        + cs_ac_interface.audio_streaming_interfaces
+        + cs_ac_interface.midi_streaming_interfaces
+    )
+
+if include_vendor:
+    # Vendor-specific interface, for example WebUSB
+    vendor_endpoint_in_descriptor = standard.EndpointDescriptor(
+        description="VENDOR in",
+        bEndpointAddress=args.vendor_ep_num_in
+        | standard.EndpointDescriptor.DIRECTION_IN,
+        bmAttributes=standard.EndpointDescriptor.TYPE_BULK,
+        bInterval=16,
+    )
+
+    vendor_endpoint_out_descriptor = standard.EndpointDescriptor(
+        description="VENDOR out",
+        bEndpointAddress=args.vendor_ep_num_out
+        | standard.EndpointDescriptor.DIRECTION_OUT,
+        bmAttributes=standard.EndpointDescriptor.TYPE_BULK,
+        bInterval=16,
+    )
+
     vendor_interface = standard.InterfaceDescriptor(
         description="VENDOR",
-        bInterfaceClass=0xff, # Vendor-specific
+        bInterfaceClass=0xFF,  # Vendor-specific
         bInterfaceSubClass=0x00,
         bInterfaceProtocol=0x00,
         iInterface=StringIndex.index("{} VENDOR".format(args.interface_name)),
         subdescriptors=[
             vendor_endpoint_in_descriptor,
             vendor_endpoint_out_descriptor,
-        ]
+        ],
     )
 
     vendor_interfaces = [vendor_interface]
 
 interfaces_to_join = []
 
-if 'CDC' in args.devices:
+if include_cdc:
     interfaces_to_join.append(cdc_interfaces)
 
-if 'MSC' in args.devices:
+if include_cdc2:
+    interfaces_to_join.append(cdc2_interfaces)
+
+if include_msc:
     interfaces_to_join.append(msc_interfaces)
 
-if 'HID' in args.devices:
+if include_hid:
     interfaces_to_join.append(hid_interfaces)
 
-if 'AUDIO' in args.devices:
+if include_audio:
     interfaces_to_join.append(audio_interfaces)
 
-if 'VENDOR' in args.devices:
+if include_vendor:
     interfaces_to_join.append(vendor_interfaces)
 
 # util.join_interfaces() will renumber the endpoints to make them unique across descriptors,
 # and renumber the interfaces in order. But we still need to fix up certain
 # interface cross-references.
-interfaces = util.join_interfaces(interfaces_to_join, renumber_endpoints=args.renumber_endpoints)
+interfaces = util.join_interfaces(
+    interfaces_to_join, renumber_endpoints=args.renumber_endpoints
+)
 
 if args.max_ep != 0:
     for interface in interfaces:
         for subdescriptor in interface.subdescriptors:
-            endpoint_address = getattr(subdescriptor, 'bEndpointAddress', 0) & 0x7f
+            endpoint_address = getattr(subdescriptor, "bEndpointAddress", 0) & 0x7F
             if endpoint_address >= args.max_ep:
-                raise ValueError("Endpoint address %d of %s must be less than %d" % (endpoint_address & 0x7f, interface.description, args.max_ep))
+                raise ValueError(
+                    "Endpoint address %d of '%s' must be less than %d; you have probably run out of endpoints"
+                    % (endpoint_address & 0x7F, interface.description, args.max_ep)
+                )
 else:
-    print("Unable to check whether maximum number of endpoints is respected", file=sys.stderr)
+    print(
+        "Unable to check whether maximum number of endpoints is respected",
+        file=sys.stderr,
+    )
 
 # Now adjust the CDC interface cross-references.
 
-cdc_union.bMasterInterface = cdc_comm_interface.bInterfaceNumber
-cdc_union.bSlaveInterface_list = [cdc_data_interface.bInterfaceNumber]
+if include_cdc:
+    cdc_union.bMasterInterface = cdc_comm_interface.bInterfaceNumber
+    cdc_union.bSlaveInterface_list = [cdc_data_interface.bInterfaceNumber]
+
+    cdc_call_management.bDataInterface = cdc_data_interface.bInterfaceNumber
 
-cdc_call_management.bDataInterface = cdc_data_interface.bInterfaceNumber
+if include_cdc2:
+    cdc2_union.bMasterInterface = cdc2_comm_interface.bInterfaceNumber
+    cdc2_union.bSlaveInterface_list = [cdc2_data_interface.bInterfaceNumber]
 
-cdc_iad = standard.InterfaceAssociationDescriptor(
-    description="CDC IAD",
-    bFirstInterface=cdc_comm_interface.bInterfaceNumber,
-    bInterfaceCount=len(cdc_interfaces),
-    bFunctionClass=cdc.CDC_CLASS_COMM,  # Communications Device Class
-    bFunctionSubClass=cdc.CDC_SUBCLASS_ACM,  # Abstract control model
-    bFunctionProtocol=cdc.CDC_PROTOCOL_NONE)
+    cdc2_call_management.bDataInterface = cdc2_data_interface.bInterfaceNumber
+
+
+def make_cdc_iad(cdc_comm_interface, name):
+    return standard.InterfaceAssociationDescriptor(
+        description="{} IAD".format(name),
+        bFirstInterface=cdc_comm_interface.bInterfaceNumber,
+        bInterfaceCount=len(cdc_interfaces),
+        bFunctionClass=cdc.CDC_CLASS_COMM,  # Communications Device Class
+        bFunctionSubClass=cdc.CDC_SUBCLASS_ACM,  # Abstract control model
+        bFunctionProtocol=cdc.CDC_PROTOCOL_NONE,
+    )
+
+
+if include_cdc:
+    cdc_iad = make_cdc_iad(cdc_comm_interface, "CDC")
+if include_cdc2:
+    cdc2_iad = make_cdc_iad(cdc2_comm_interface, "CDC2")
 
 descriptor_list = []
 
-if 'CDC' in args.devices:
+if include_cdc:
     # Put the CDC IAD just before the CDC interfaces.
     # There appears to be a bug in the Windows composite USB driver that requests the
     # HID report descriptor with the wrong interface number if the HID interface is not given
@@ -462,37 +645,47 @@ if 'CDC' in args.devices:
     descriptor_list.append(cdc_iad)
     descriptor_list.extend(cdc_interfaces)
 
-if 'MSC' in args.devices:
+if include_cdc2:
+    descriptor_list.append(cdc2_iad)
+    descriptor_list.extend(cdc2_interfaces)
+
+if include_msc:
     descriptor_list.extend(msc_interfaces)
 
-if 'HID' in args.devices:
+if include_hid:
     descriptor_list.extend(hid_interfaces)
 
-if 'AUDIO' in args.devices:
+if include_audio:
     # Only add the control interface because other audio interfaces are managed by it to ensure the
     # correct ordering.
     descriptor_list.append(audio_control_interface)
 
-if 'VENDOR' in args.devices:
+if include_vendor:
     descriptor_list.extend(vendor_interfaces)
 
 # Finally, build the composite descriptor.
 
 configuration = standard.ConfigurationDescriptor(
     description="Composite configuration",
-    wTotalLength=(standard.ConfigurationDescriptor.bLength +
-                  sum([len(bytes(x)) for x in descriptor_list])),
-    bNumInterfaces=len(interfaces))
+    wTotalLength=(
+        standard.ConfigurationDescriptor.bLength
+        + sum([len(bytes(x)) for x in descriptor_list])
+    ),
+    bNumInterfaces=len(interfaces),
+)
 descriptor_list.insert(0, configuration)
 
-string_descriptors = [standard.StringDescriptor(string) for string in StringIndex.strings_in_order()]
+string_descriptors = [
+    standard.StringDescriptor(string) for string in StringIndex.strings_in_order()
+]
 serial_number_descriptor = string_descriptors[SERIAL_NUMBER_INDEX]
 
 c_file = args.output_c_file
 h_file = args.output_h_file
 
 
-c_file.write("""\
+c_file.write(
+    """\
 #include <stdint.h>
 
 #include "tusb.h"
@@ -500,34 +693,49 @@ c_file.write("""\
 #include "shared-bindings/usb_hid/Device.h"
 #include "{H_FILE_NAME}"
 
-""".format(H_FILE_NAME=h_file.name))
+""".format(
+        H_FILE_NAME=h_file.name
+    )
+)
 
-c_file.write("""\
+c_file.write(
+    """\
 // {DESCRIPTION} : {CLASS}
-""".format(DESCRIPTION=device.description,
-           CLASS=device.__class__))
+""".format(
+        DESCRIPTION=device.description, CLASS=device.__class__
+    )
+)
 
-c_file.write("""\
+c_file.write(
+    """\
 const uint8_t usb_desc_dev[] = {
-""")
+"""
+)
 for b in bytes(device):
     c_file.write("0x{:02x}, ".format(b))
 
-c_file.write("""\
+c_file.write(
+    """\
 };
-""")
+"""
+)
 
-c_file.write("""\
+c_file.write(
+    """\
 const uint8_t usb_desc_cfg[] = {
-""")
+"""
+)
 
 # Write out all the regular descriptors as one long array (that's how ASF4 does it).
 descriptor_length = 0
 for descriptor in descriptor_list:
-    c_file.write("""\
+    c_file.write(
+        """\
 // {DESCRIPTION} : {CLASS}
-""".format(DESCRIPTION=descriptor.description,
-               CLASS=descriptor.__class__))
+""".format(
+            DESCRIPTION=descriptor.description, CLASS=descriptor.__class__
+        )
+    )
 
     b = bytes(descriptor)
     notes = descriptor.notes()
@@ -545,17 +753,22 @@ for descriptor in descriptor_list:
         i += length
     descriptor_length += len(b)
 
-c_file.write("""\
+c_file.write(
+    """\
 };
-""")
+"""
+)
 
 pointers_to_strings = []
 
 for idx, descriptor in enumerate(string_descriptors):
-    c_file.write("""\
+    c_file.write(
+        """\
 // {DESCRIPTION} : {CLASS}
-""".format(DESCRIPTION=descriptor.description,
-               CLASS=descriptor.__class__))
+""".format(
+            DESCRIPTION=descriptor.description, CLASS=descriptor.__class__
+        )
+    )
 
     b = bytes(descriptor)
     notes = descriptor.notes()
@@ -569,41 +782,59 @@ for idx, descriptor in enumerate(string_descriptors):
     const = "const "
     if variable_name == "usb_serial_number":
         const = ""
-    c_file.write("""\
+    c_file.write(
+        """\
 {const}uint16_t {NAME}[] = {{
-""".format(const=const, NAME=variable_name))
+""".format(
+            const=const, NAME=variable_name
+        )
+    )
     pointers_to_strings.append("{name}".format(name=variable_name))
     n = 0
     while i < len(b):
         length = b[i]
         for j in range(length // 2):
-            c_file.write("0x{:04x}, ".format(b[i + 2*j + 1] << 8 | b[i + 2*j]))
+            c_file.write("0x{:04x}, ".format(b[i + 2 * j + 1] << 8 | b[i + 2 * j]))
         n += 1
         c_file.write("\n")
         i += length
-    c_file.write("""\
+    c_file.write(
+        """\
 };
-""")
+"""
+    )
 
-c_file.write("""\
+c_file.write(
+    """\
 // array of pointer to string descriptors
 uint16_t const * const string_desc_arr [] =
 {
-""")
-c_file.write(""",\
+"""
+)
+c_file.write(
+    """,\
 
-""".join(pointers_to_strings))
+""".join(
+        pointers_to_strings
+    )
+)
 
-c_file.write("""
+c_file.write(
+    """
 };
-""")
+"""
+)
 
 c_file.write("\n")
 
-hid_descriptor_length = len(bytes(combined_hid_report_descriptor))
+if include_hid:
+    hid_descriptor_length = len(bytes(combined_hid_report_descriptor))
+else:
+    hid_descriptor_length = 0
 
 # Now the values we need for the .h file.
-h_file.write("""\
+h_file.write(
+    """\
 #ifndef MICROPY_INCLUDED_AUTOGEN_USB_DESCRIPTOR_H
 #define MICROPY_INCLUDED_AUTOGEN_USB_DESCRIPTOR_H
 
@@ -614,32 +845,43 @@ extern const uint8_t usb_desc_cfg[{configuration_length}];
 extern uint16_t usb_serial_number[{serial_number_length}];
 extern uint16_t const * const string_desc_arr [{string_descriptor_length}];
 
-extern const uint8_t hid_report_descriptor[{hid_report_descriptor_length}];
-
 #define CFG_TUSB_RHPORT0_MODE       ({rhport0_mode})
 
-#define USB_HID_NUM_DEVICES         {hid_num_devices}
-
 // Vendor name included in Inquiry response, max 8 bytes
 #define CFG_TUD_MSC_VENDOR          "{msc_vendor}"
 
 // Product name included in Inquiry response, max 16 bytes
 #define CFG_TUD_MSC_PRODUCT         "{msc_product}"
 
-"""
-.format(serial_number_length=len(bytes(serial_number_descriptor)) // 2,
+""".format(
+        serial_number_length=len(bytes(serial_number_descriptor)) // 2,
         device_length=len(bytes(device)),
         configuration_length=descriptor_length,
         max_configuration_length=max(hid_descriptor_length, descriptor_length),
         string_descriptor_length=len(pointers_to_strings),
-        hid_report_descriptor_length=len(bytes(combined_hid_report_descriptor)),
-        rhport0_mode='OPT_MODE_DEVICE | OPT_MODE_HIGH_SPEED' if args.highspeed else 'OPT_MODE_DEVICE',
-        hid_num_devices=len(args.hid_devices),
+        rhport0_mode="OPT_MODE_DEVICE | OPT_MODE_HIGH_SPEED"
+        if args.highspeed
+        else "OPT_MODE_DEVICE",
         msc_vendor=args.manufacturer[:8],
-        msc_product=args.product[:16]))
+        msc_product=args.product[:16],
+    )
+)
 
-if 'VENDOR' in args.devices:
-    h_file.write("""\
+if include_hid:
+    h_file.write(
+        """\
+extern const uint8_t hid_report_descriptor[{hid_report_descriptor_length}];
+
+#define USB_HID_NUM_DEVICES         {hid_num_devices}
+""".format(
+            hid_report_descriptor_length=len(bytes(combined_hid_report_descriptor)),
+            hid_num_devices=len(args.hid_devices),
+        )
+    )
+
+if include_vendor:
+    h_file.write(
+        """\
 enum
 {
   VENDOR_REQUEST_WEBUSB = 1,
@@ -652,43 +894,75 @@ extern uint8_t const desc_ms_os_20[];
 // if we try do define this here (TODO figure this out!)
 //extern const tusb_desc_webusb_url_t desc_webusb_url;
 
-""")
+"""
+    )
 
-h_file.write("""\
+h_file.write(
+    """\
 #endif // MICROPY_INCLUDED_AUTOGEN_USB_DESCRIPTOR_H
-""")
-# Write out the report descriptor and info
+"""
+)
 
-c_file.write("""\
+if include_hid:
+    # Write out the report descriptor and info
+    c_file.write(
+        """\
 const uint8_t hid_report_descriptor[{HID_DESCRIPTOR_LENGTH}] = {{
-""".format(HID_DESCRIPTOR_LENGTH=hid_descriptor_length))
+""".format(
+            HID_DESCRIPTOR_LENGTH=hid_descriptor_length
+        )
+    )
 
-for b in bytes(combined_hid_report_descriptor):
-    c_file.write("0x{:02x}, ".format(b))
-c_file.write("""\
+    for b in bytes(combined_hid_report_descriptor):
+        c_file.write("0x{:02x}, ".format(b))
+
+    c_file.write(
+        """\
 };
 
-""")
+"""
+    )
 
-# Write out USB HID report buffer definitions.
-for name in args.hid_devices:
-    c_file.write("""\
+    # Write out USB HID report buffer definitions.
+    for name in args.hid_devices:
+        c_file.write(
+            """\
 static uint8_t {name}_report_buffer[{report_length}];
-""".format(name=name.lower(), report_length=hid_report_descriptors.HID_DEVICE_DATA[name].report_length))
-
-    if hid_report_descriptors.HID_DEVICE_DATA[name].out_report_length > 0:
-        c_file.write("""\
+""".format(
+                name=name.lower(),
+                report_length=hid_report_descriptors.HID_DEVICE_DATA[
+                    name
+                ].report_length,
+            )
+        )
+
+        if hid_report_descriptors.HID_DEVICE_DATA[name].out_report_length > 0:
+            c_file.write(
+                """\
 static uint8_t {name}_out_report_buffer[{report_length}];
-""".format(name=name.lower(), report_length=hid_report_descriptors.HID_DEVICE_DATA[name].out_report_length))
-
-# Write out table of device objects.
-c_file.write("""
+""".format(
+                    name=name.lower(),
+                    report_length=hid_report_descriptors.HID_DEVICE_DATA[
+                        name
+                    ].out_report_length,
+                )
+            )
+
+    # Write out table of device objects.
+    c_file.write(
+        """\
 usb_hid_device_obj_t usb_hid_devices[] = {
-""")
-for name in args.hid_devices:
-    device_data = hid_report_descriptors.HID_DEVICE_DATA[name]
-    out_report_buffer = '{}_out_report_buffer'.format(name.lower()) if device_data.out_report_length > 0 else 'NULL'
-    c_file.write("""\
+"""
+    )
+    for name in args.hid_devices:
+        device_data = hid_report_descriptors.HID_DEVICE_DATA[name]
+        out_report_buffer = (
+            "{}_out_report_buffer".format(name.lower())
+            if device_data.out_report_length > 0
+            else "NULL"
+        )
+        c_file.write(
+            """\
     {{
         .base          = {{ .type = &usb_hid_device_type }},
         .report_buffer = {name}_report_buffer,
@@ -699,37 +973,54 @@ for name in args.hid_devices:
         .out_report_buffer = {out_report_buffer},
         .out_report_length = {out_report_length},
     }},
-""".format(name=name.lower(), report_id=report_ids[name],
-           report_length=device_data.report_length,
-           usage_page=device_data.usage_page,
-           usage=device_data.usage,
-           out_report_buffer=out_report_buffer,
-           out_report_length=device_data.out_report_length))
-c_file.write("""\
+""".format(
+                name=name.lower(),
+                report_id=report_ids[name],
+                report_length=device_data.report_length,
+                usage_page=device_data.usage_page,
+                usage=device_data.usage,
+                out_report_buffer=out_report_buffer,
+                out_report_length=device_data.out_report_length,
+            )
+        )
+    c_file.write(
+        """\
 };
-""")
+"""
+    )
 
-# Write out tuple of device objects.
-c_file.write("""
+    # Write out tuple of device objects.
+    c_file.write(
+        """
 mp_obj_tuple_t common_hal_usb_hid_devices = {{
     .base = {{
         .type = &mp_type_tuple,
     }},
     .len = {num_devices},
     .items = {{
-""".format(num_devices=len(args.hid_devices)))
-for idx in range(len(args.hid_devices)):
-    c_file.write("""\
+""".format(
+            num_devices=len(args.hid_devices)
+        )
+    )
+    for idx in range(len(args.hid_devices)):
+        c_file.write(
+            """\
          (mp_obj_t) &usb_hid_devices[{idx}],
-""".format(idx=idx))
-c_file.write("""\
+""".format(
+                idx=idx
+            )
+        )
+    c_file.write(
+        """\
     },
 };
-""")
+"""
+    )
 
-if 'VENDOR' in args.devices:
-    # Mimic what the tinyusb webusb demo does in it's main.c file
-    c_file.write("""
+if include_vendor:
+    # Mimic what the tinyusb webusb demo does in its main.c file
+    c_file.write(
+        """
 #define URL   "{webusb_url}"
 
 const tusb_desc_webusb_url_t desc_webusb_url =
@@ -819,4 +1110,8 @@ TU_VERIFY_STATIC(sizeof(desc_ms_os_20) == MS_OS_20_DESC_LEN, "Incorrect size");
 
 // End of section about desc_ms_os_20
 
-""".format(webusb_url=args.webusb_url, webusb_interface=vendor_interface.bInterfaceNumber))
+""".format(
+            webusb_url=args.webusb_url,
+            webusb_interface=vendor_interface.bInterfaceNumber,
+        )
+    )
diff --git a/tools/usb_descriptor b/tools/usb_descriptor
-Subproject 701cafc50e2e574dccaf7a340eedbd64a0b41a4
+Subproject 2eaa6114b209fe7f0a795eda8d6a7b3b93d76d2