Turn on nvm in 3.0.

Its 256b on M0 and 8k on M4 to match flash erase sizes.

Fixes #758

24 files changed, 55 insertions, 125 deletions

diff --git a/ports/atmel-samd/Makefile b/ports/atmel-samd/Makefile
index 7d2982ca0..2f01abc4f 100644
--- a/ports/atmel-samd/Makefile
+++ b/ports/atmel-samd/Makefile
@@ -285,6 +285,8 @@ SRC_COMMON_HAL = \
 	analogio/__init__.c \
 	analogio/AnalogIn.c \
 	analogio/AnalogOut.c \
+	nvm/__init__.c \
+	nvm/ByteArray.c \
 	pulseio/__init__.c \
 	pulseio/PulseIn.c \
 	pulseio/PulseOut.c \
@@ -293,9 +295,7 @@ SRC_COMMON_HAL = \
 	usb_hid/Device.c \
 	audioio/__init__.c \
 	audioio/AudioOut.c \
-#	nvm/__init__.c \
-	audiobusio/PDMIn.c \
-	nvm/ByteArray.c \
+#	audiobusio/PDMIn.c \
 	touchio/__init__.c \
 	touchio/TouchIn.c \
 
diff --git a/ports/atmel-samd/boards/circuitplayground_express/mpconfigboard.h b/ports/atmel-samd/boards/circuitplayground_express/mpconfigboard.h
index 02802a6a9..73d45f2cf 100644
--- a/ports/atmel-samd/boards/circuitplayground_express/mpconfigboard.h
+++ b/ports/atmel-samd/boards/circuitplayground_express/mpconfigboard.h
@@ -42,8 +42,7 @@
 
 // If you change this, then make sure to update the linker scripts as well to
 // make sure you don't overwrite code.
-// #define CIRCUITPY_INTERNAL_NVM_SIZE 256
-#define CIRCUITPY_INTERNAL_NVM_SIZE 0
+#define CIRCUITPY_INTERNAL_NVM_SIZE 256
 
 #define BOARD_FLASH_SIZE (0x00040000 - 0x2000 - CIRCUITPY_INTERNAL_NVM_SIZE)
 
diff --git a/ports/atmel-samd/boards/feather_m0_express/mpconfigboard.h b/ports/atmel-samd/boards/feather_m0_express/mpconfigboard.h
index ef13bcafe..56e9c8bb7 100644
--- a/ports/atmel-samd/boards/feather_m0_express/mpconfigboard.h
+++ b/ports/atmel-samd/boards/feather_m0_express/mpconfigboard.h
@@ -35,8 +35,7 @@
 
 // If you change this, then make sure to update the linker scripts as well to
 // make sure you don't overwrite code.
-// #define CIRCUITPY_INTERNAL_NVM_SIZE 256
-#define CIRCUITPY_INTERNAL_NVM_SIZE 0
+#define CIRCUITPY_INTERNAL_NVM_SIZE 256
 
 #define BOARD_FLASH_SIZE (0x00040000 - 0x2000 - CIRCUITPY_INTERNAL_NVM_SIZE)
 
diff --git a/ports/atmel-samd/boards/feather_m0_supersized/mpconfigboard.h b/ports/atmel-samd/boards/feather_m0_supersized/mpconfigboard.h
index 883d7a2e5..5bc74d5a7 100644
--- a/ports/atmel-samd/boards/feather_m0_supersized/mpconfigboard.h
+++ b/ports/atmel-samd/boards/feather_m0_supersized/mpconfigboard.h
@@ -37,8 +37,7 @@
 
 // If you change this, then make sure to update the linker scripts as well to
 // make sure you don't overwrite code.
-// #define CIRCUITPY_INTERNAL_NVM_SIZE 256
-#define CIRCUITPY_INTERNAL_NVM_SIZE 0
+#define CIRCUITPY_INTERNAL_NVM_SIZE 256
 
 #define BOARD_FLASH_SIZE (0x00040000 - 0x2000 - CIRCUITPY_INTERNAL_NVM_SIZE)
 
diff --git a/ports/atmel-samd/boards/feather_m4_express/mpconfigboard.h b/ports/atmel-samd/boards/feather_m4_express/mpconfigboard.h
index bd56a7bdf..6e1022256 100644
--- a/ports/atmel-samd/boards/feather_m4_express/mpconfigboard.h
+++ b/ports/atmel-samd/boards/feather_m4_express/mpconfigboard.h
@@ -19,8 +19,7 @@
 
 // If you change this, then make sure to update the linker scripts as well to
 // make sure you don't overwrite code
-// #define CIRCUITPY_INTERNAL_NVM_SIZE 256
-#define CIRCUITPY_INTERNAL_NVM_SIZE 0
+#define CIRCUITPY_INTERNAL_NVM_SIZE 8192
 
 #define BOARD_FLASH_SIZE (FLASH_SIZE - 0x4000 - CIRCUITPY_INTERNAL_NVM_SIZE)
 
diff --git a/ports/atmel-samd/boards/itsybitsy_m0_express/mpconfigboard.h b/ports/atmel-samd/boards/itsybitsy_m0_express/mpconfigboard.h
index 675b9a30d..a7ecd27ea 100644
--- a/ports/atmel-samd/boards/itsybitsy_m0_express/mpconfigboard.h
+++ b/ports/atmel-samd/boards/itsybitsy_m0_express/mpconfigboard.h
@@ -35,8 +35,8 @@
 
 // If you change this, then make sure to update the linker scripts as well to
 // make sure you don't overwrite code.
-// #define CIRCUITPY_INTERNAL_NVM_SIZE 256
-#define CIRCUITPY_INTERNAL_NVM_SIZE 0
+#define CIRCUITPY_INTERNAL_NVM_SIZE 256
+
 #define BOARD_FLASH_SIZE (0x00040000 - 0x2000 - CIRCUITPY_INTERNAL_NVM_SIZE)
 
 #include "external_flash/devices.h"
diff --git a/ports/atmel-samd/boards/itsybitsy_m4_express/mpconfigboard.h b/ports/atmel-samd/boards/itsybitsy_m4_express/mpconfigboard.h
index 7f6319152..63fbc8cb8 100644
--- a/ports/atmel-samd/boards/itsybitsy_m4_express/mpconfigboard.h
+++ b/ports/atmel-samd/boards/itsybitsy_m4_express/mpconfigboard.h
@@ -19,8 +19,7 @@
 
 // If you change this, then make sure to update the linker scripts as well to
 // make sure you don't overwrite code
-// #define CIRCUITPY_INTERNAL_NVM_SIZE 256
-#define CIRCUITPY_INTERNAL_NVM_SIZE 0
+#define CIRCUITPY_INTERNAL_NVM_SIZE 8192
 
 #define BOARD_FLASH_SIZE (FLASH_SIZE - 0x4000 - CIRCUITPY_INTERNAL_NVM_SIZE)
 
diff --git a/ports/atmel-samd/boards/metro_m0_express/mpconfigboard.h b/ports/atmel-samd/boards/metro_m0_express/mpconfigboard.h
index c8ceaa386..a433e9949 100644
--- a/ports/atmel-samd/boards/metro_m0_express/mpconfigboard.h
+++ b/ports/atmel-samd/boards/metro_m0_express/mpconfigboard.h
@@ -36,8 +36,7 @@
 
 // If you change this, then make sure to update the linker scripts as well to
 // make sure you don't overwrite code.
-// #define CIRCUITPY_INTERNAL_NVM_SIZE 256
-#define CIRCUITPY_INTERNAL_NVM_SIZE 0
+#define CIRCUITPY_INTERNAL_NVM_SIZE 256
 
 #define BOARD_FLASH_SIZE (0x00040000 - 0x2000 - CIRCUITPY_INTERNAL_NVM_SIZE)
 
diff --git a/ports/atmel-samd/boards/metro_m4_express/mpconfigboard.h b/ports/atmel-samd/boards/metro_m4_express/mpconfigboard.h
index e2b7f9982..701203771 100644
--- a/ports/atmel-samd/boards/metro_m4_express/mpconfigboard.h
+++ b/ports/atmel-samd/boards/metro_m4_express/mpconfigboard.h
@@ -22,8 +22,7 @@
 
 // If you change this, then make sure to update the linker scripts as well to
 // make sure you don't overwrite code
-// #define CIRCUITPY_INTERNAL_NVM_SIZE 256
-#define CIRCUITPY_INTERNAL_NVM_SIZE 0
+#define CIRCUITPY_INTERNAL_NVM_SIZE 8192
 
 #define BOARD_FLASH_SIZE (FLASH_SIZE - 0x4000 - CIRCUITPY_INTERNAL_NVM_SIZE)
 
diff --git a/ports/atmel-samd/boards/metro_m4_express_revb/mpconfigboard.h b/ports/atmel-samd/boards/metro_m4_express_revb/mpconfigboard.h
index 7af9767ca..206d85465 100644
--- a/ports/atmel-samd/boards/metro_m4_express_revb/mpconfigboard.h
+++ b/ports/atmel-samd/boards/metro_m4_express_revb/mpconfigboard.h
@@ -49,8 +49,7 @@
 
 // If you change this, then make sure to update the linker scripts as well to
 // make sure you don't overwrite code
-// #define CIRCUITPY_INTERNAL_NVM_SIZE 256
-#define CIRCUITPY_INTERNAL_NVM_SIZE 0
+#define CIRCUITPY_INTERNAL_NVM_SIZE 8192
 
 #define BOARD_FLASH_SIZE (FLASH_SIZE - 0x4000 - CIRCUITPY_INTERNAL_NVM_SIZE)
 
diff --git a/ports/atmel-samd/boards/samd51x18-bootloader-external-flash.ld b/ports/atmel-samd/boards/samd51x18-bootloader-external-flash.ld
index 0bd2a8297..c0e812ce1 100644
--- a/ports/atmel-samd/boards/samd51x18-bootloader-external-flash.ld
+++ b/ports/atmel-samd/boards/samd51x18-bootloader-external-flash.ld
@@ -5,8 +5,8 @@
 /* Specify the memory areas */
 MEMORY
 {
-    /* Leave 16KiB for the bootloader. */
-    FLASH (rx) : ORIGIN = 0x00000000 + 16K, LENGTH = 256K - 16K
+    /* Leave 16KiB for the bootloader. 8K for user data*/
+    FLASH (rx) : ORIGIN = 0x00000000 + 16K, LENGTH = 256K - 16K - 8K
     RAM (xrw)  : ORIGIN = 0x20000000, LENGTH = 128K
 }
 
@@ -76,7 +76,7 @@ SECTIONS
     .stack :
     {
         . = ALIGN(4);
-        . = . + 2K; /* Reserve a minimum of 2K for the stack. */
+        . = . + 10K; /* Reserve a minimum of 10K for the stack. nvm will temporarily store 8k on the stack when writing. */
         . = ALIGN(4);
     } >RAM
 
diff --git a/ports/atmel-samd/boards/samd51x19-bootloader-external-flash.ld b/ports/atmel-samd/boards/samd51x19-bootloader-external-flash.ld
index b6b4f3265..253a764c9 100644
--- a/ports/atmel-samd/boards/samd51x19-bootloader-external-flash.ld
+++ b/ports/atmel-samd/boards/samd51x19-bootloader-external-flash.ld
@@ -5,8 +5,8 @@
 /* Specify the memory areas */
 MEMORY
 {
-    /* Leave 16KiB for the bootloader. */
-    FLASH (rx) : ORIGIN = 0x00000000 + 16K, LENGTH = 512K - 16K
+    /* Leave 16KiB for the bootloader. 8K for user data*/
+    FLASH (rx) : ORIGIN = 0x00000000 + 16K, LENGTH = 512K - 16K - 8K
     RAM (xrw)  : ORIGIN = 0x20000000, LENGTH = 192K
 }
 
@@ -76,7 +76,7 @@ SECTIONS
     .stack :
     {
         . = ALIGN(4);
-        . = . + 2K; /* Reserve a minimum of 2K for the stack. */
+        . = . + 10K; /* Reserve a minimum of 10K for the stack. nvm will temporarily store 8k on the stack when writing. */
         . = ALIGN(4);
     } >RAM
 
diff --git a/ports/atmel-samd/boards/samd51x19-bootloader.ld b/ports/atmel-samd/boards/samd51x19-bootloader.ld
index 4876e8227..56786a37a 100644
--- a/ports/atmel-samd/boards/samd51x19-bootloader.ld
+++ b/ports/atmel-samd/boards/samd51x19-bootloader.ld
@@ -5,8 +5,8 @@
 /* Specify the memory areas */
 MEMORY
 {
-    /* Leave 16KiB for the bootloader and 256KiB for the internal file system. */
-    FLASH (rx) : ORIGIN = 0x00000000 + 16K, LENGTH = 512K - 16K - 256K
+    /* Leave 16KiB for the bootloader, 256KiB for the internal file system, and 8KiB for user binary data. */
+    FLASH (rx) : ORIGIN = 0x00000000 + 16K, LENGTH = 512K - 16K - 256K - 8K
     RAM (xrw)  : ORIGIN = 0x20000000, LENGTH = 192K
 }
 
@@ -76,7 +76,7 @@ SECTIONS
     .stack :
     {
         . = ALIGN(4);
-        . = . + 2K; /* Reserve a minimum of 2K for the stack. */
+        . = . + 10K; /* Reserve a minimum of 10K for the stack. nvm will temporarily store 8k on the stack when writing. */
         . = ALIGN(4);
     } >RAM
 
diff --git a/ports/atmel-samd/boards/samd51x20-bootloader-external-flash.ld b/ports/atmel-samd/boards/samd51x20-bootloader-external-flash.ld
index 3a1611279..598915b1b 100644
--- a/ports/atmel-samd/boards/samd51x20-bootloader-external-flash.ld
+++ b/ports/atmel-samd/boards/samd51x20-bootloader-external-flash.ld
@@ -6,7 +6,7 @@
 MEMORY
 {
     /* Leave 16KiB for the bootloader. */
-    FLASH (rx) : ORIGIN = 0x00000000 + 16K, LENGTH = 1M - 16K
+    FLASH (rx) : ORIGIN = 0x00000000 + 16K, LENGTH = 1M - 16K - 8K
     RAM (xrw)  : ORIGIN = 0x20000000, LENGTH = 256K
 }
 
@@ -76,7 +76,7 @@ SECTIONS
     .stack :
     {
         . = ALIGN(4);
-        . = . + 2K; /* Reserve a minimum of 2K for the stack. */
+        . = . + 10K; /* Reserve a minimum of 10K for the stack. nvm will temporarily store 8k on the stack when writing. */
         . = ALIGN(4);
     } >RAM
 
diff --git a/ports/atmel-samd/boards/samd51x20-bootloader.ld b/ports/atmel-samd/boards/samd51x20-bootloader.ld
index d3d37de3b..49d4d8791 100644
--- a/ports/atmel-samd/boards/samd51x20-bootloader.ld
+++ b/ports/atmel-samd/boards/samd51x20-bootloader.ld
@@ -5,8 +5,8 @@
 /* Specify the memory areas */
 MEMORY
 {
-    /* Leave 16KiB for the bootloader and 512k for the filesystem. */
-    FLASH (rx) : ORIGIN = 0x00000000 + 16K, LENGTH = 1M - 16K - 512K
+    /* Leave 16KiB for the bootloader, 512k for the filesystem and 8k for user config data. */
+    FLASH (rx) : ORIGIN = 0x00000000 + 16K, LENGTH = 1M - 16K - 512K - 8K
     RAM (xrw)  : ORIGIN = 0x20000000, LENGTH = 256K
 }
 
@@ -76,7 +76,7 @@ SECTIONS
     .stack :
     {
         . = ALIGN(4);
-        . = . + 2K; /* Reserve a minimum of 2K for the stack. */
+        . = . + 10K; /* Reserve a minimum of 10K for the stack. nvm will temporarily store 8k on the stack when writing. */
         . = ALIGN(4);
     } >RAM
 
diff --git a/ports/atmel-samd/boards/samd51x20-external-flash.ld b/ports/atmel-samd/boards/samd51x20-external-flash.ld
index e31f31a58..d3ed90476 100644
--- a/ports/atmel-samd/boards/samd51x20-external-flash.ld
+++ b/ports/atmel-samd/boards/samd51x20-external-flash.ld
@@ -5,7 +5,7 @@
 /* Specify the memory areas */
 MEMORY
 {
-    FLASH (rx) : ORIGIN = 0x00000000, LENGTH = 1M
+    FLASH (rx) : ORIGIN = 0x00000000, LENGTH = 1M - 8K
     RAM (xrw)  : ORIGIN = 0x20000000, LENGTH = 256K
 }
 
@@ -74,7 +74,7 @@ SECTIONS
     .stack :
     {
         . = ALIGN(4);
-        . = . + 2K; /* Reserve a minimum of 2K for the stack. */
+        . = . + 10K; /* Reserve a minimum of 10K for the stack. nvm will temporarily store 8k on the stack when writing. */
         . = ALIGN(4);
     } >RAM
 
diff --git a/ports/atmel-samd/boards/samd51x20.ld b/ports/atmel-samd/boards/samd51x20.ld
index 4c44c7fa8..e203c5b7a 100644
--- a/ports/atmel-samd/boards/samd51x20.ld
+++ b/ports/atmel-samd/boards/samd51x20.ld
@@ -5,8 +5,8 @@
 /* Specify the memory areas */
 MEMORY
 {
-    /* 1024 KiB minus 512KiB for the internal file system. */
-    FLASH (rx) : ORIGIN = 0x00000000, LENGTH = 1M - 512K
+    /* 1024 KiB minus 512KiB for the internal file system and 8KiB for the user nvm. */
+    FLASH (rx) : ORIGIN = 0x00000000, LENGTH = 1M - 512K - 8K
     RAM (xrw)  : ORIGIN = 0x20000000, LENGTH = 256K
 }
 
@@ -75,7 +75,7 @@ SECTIONS
     .stack :
     {
         . = ALIGN(4);
-        . = . + 2K; /* Reserve a minimum of 2K for the stack. */
+        . = . + 10K; /* Reserve a minimum of 10K for the stack. nvm will temporarily store 8k on the stack when writing. */
         . = ALIGN(4);
     } >RAM
 
diff --git a/ports/atmel-samd/boards/trinket_m0_haxpress/mpconfigboard.h b/ports/atmel-samd/boards/trinket_m0_haxpress/mpconfigboard.h
index 340e25e59..ea45c1f8b 100644
--- a/ports/atmel-samd/boards/trinket_m0_haxpress/mpconfigboard.h
+++ b/ports/atmel-samd/boards/trinket_m0_haxpress/mpconfigboard.h
@@ -44,8 +44,8 @@
 
 // If you change this, then make sure to update the linker scripts as well to
 // make sure you don't overwrite code.
-//#define CIRCUITPY_INTERNAL_NVM_SIZE 256
-#define CIRCUITPY_INTERNAL_NVM_SIZE 0
+#define CIRCUITPY_INTERNAL_NVM_SIZE 256
+
 #define BOARD_FLASH_SIZE (0x00040000 - 0x2000 - CIRCUITPY_INTERNAL_NVM_SIZE)
 
 #include "external_flash/devices.h"
diff --git a/ports/atmel-samd/boards/ugame10/mpconfigboard.h b/ports/atmel-samd/boards/ugame10/mpconfigboard.h
index b9ae952a8..1652314ed 100644
--- a/ports/atmel-samd/boards/ugame10/mpconfigboard.h
+++ b/ports/atmel-samd/boards/ugame10/mpconfigboard.h
@@ -37,8 +37,8 @@
 
 // If you change this, then make sure to update the linker scripts as well to
 // make sure you don't overwrite code.
-//#define CIRCUITPY_INTERNAL_NVM_SIZE 256
-#define CIRCUITPY_INTERNAL_NVM_SIZE 0
+#define CIRCUITPY_INTERNAL_NVM_SIZE 256
+
 #define BOARD_FLASH_SIZE (0x00040000 - 0x2000 - CIRCUITPY_INTERNAL_NVM_SIZE)
 
 #include "external_flash/devices.h"
diff --git a/ports/atmel-samd/clocks.c b/ports/atmel-samd/clocks.c
index 87da2e862..be2fe0836 100644
--- a/ports/atmel-samd/clocks.c
+++ b/ports/atmel-samd/clocks.c
@@ -74,10 +74,12 @@ bool gclk_enabled(uint8_t gclk) {
 
 void disable_gclk(uint8_t gclk) {
     #ifdef SAMD51
+    while ((GCLK->SYNCBUSY.vec.GENCTRL & (1 << gclk)) != 0) {}
     GCLK->GENCTRL[gclk].bit.GENEN = false;
     while ((GCLK->SYNCBUSY.vec.GENCTRL & (1 << gclk)) != 0) {}
     #endif
     #ifdef SAMD21
+    while (GCLK->STATUS.bit.SYNCBUSY == 1) {}
     GCLK->GENCTRL.reg = GCLK_GENCTRL_ID(gclk);
     while (GCLK->STATUS.bit.SYNCBUSY == 1) {}
     #endif
diff --git a/ports/atmel-samd/common-hal/microcontroller/__init__.c b/ports/atmel-samd/common-hal/microcontroller/__init__.c
index 5839ed513..4b8c33182 100644
--- a/ports/atmel-samd/common-hal/microcontroller/__init__.c
+++ b/ports/atmel-samd/common-hal/microcontroller/__init__.c
@@ -85,13 +85,13 @@ const mcu_processor_obj_t common_hal_mcu_processor_obj = {
 // NVM is only available on Express boards for now.
 #if CIRCUITPY_INTERNAL_NVM_SIZE > 0
 // The singleton nvm.ByteArray object.
-// const nvm_bytearray_obj_t common_hal_mcu_nvm_obj = {
-//     .base = {
-//         .type = &nvm_bytearray_type,
-//     },
-//     .len = NVMCTRL_ROW_SIZE,
-//     .start_address = (uint8_t*) (FLASH_SIZE - NVMCTRL_ROW_SIZE)
-// };
+const nvm_bytearray_obj_t common_hal_mcu_nvm_obj = {
+    .base = {
+        .type = &nvm_bytearray_type,
+    },
+    .len = CIRCUITPY_INTERNAL_NVM_SIZE,
+    .start_address = (uint8_t*) (FLASH_SIZE - CIRCUITPY_INTERNAL_NVM_SIZE)
+};
 #endif
 
 // This maps MCU pin names to pin objects.
diff --git a/ports/atmel-samd/common-hal/nvm/ByteArray.c b/ports/atmel-samd/common-hal/nvm/ByteArray.c
index df8b5790e..ab9cd7d80 100644
--- a/ports/atmel-samd/common-hal/nvm/ByteArray.c
+++ b/ports/atmel-samd/common-hal/nvm/ByteArray.c
@@ -26,7 +26,7 @@
 
 #include "common-hal/nvm/ByteArray.h"
 
-#include "asf/sam0/drivers/nvm/nvm.h"
+#include "hal_flash.h"
 
 #include <stdint.h>
 #include <string.h>
@@ -36,48 +36,12 @@ uint32_t common_hal_nvm_bytearray_get_length(nvm_bytearray_obj_t *self) {
 }
 
 bool common_hal_nvm_bytearray_set_bytes(nvm_bytearray_obj_t *self,
-    uint32_t start_index, uint8_t* values, uint32_t len) {
-    uint32_t total_written = 0;
-    for (uint32_t i = 0; i < self->len / NVMCTRL_ROW_SIZE; i++) {
-        uint32_t row_start = NVMCTRL_ROW_SIZE * i;
-        if (row_start + NVMCTRL_ROW_SIZE < start_index || start_index + len < row_start) {
-            continue;
-        }
-        uint8_t temp_row[NVMCTRL_ROW_SIZE];
-        memcpy(temp_row,
-               self->start_address + row_start,
-               NVMCTRL_ROW_SIZE);
-        enum status_code error_code;
-        do {
-            error_code = nvm_erase_row((uint32_t) self->start_address + row_start);
-        } while (error_code == STATUS_BUSY);
-        if (error_code != STATUS_OK) {
-            return false;
-        }
-        uint32_t data_start = 0;
-        if (start_index > row_start) {
-            data_start = start_index - row_start;
-        }
-        uint32_t data_len = len;
-        uint32_t data_remaining = data_len - total_written;
-        uint32_t row_remaining = NVMCTRL_ROW_SIZE - data_start;
-        if (data_remaining > row_remaining) {
-            data_len = row_remaining;
-        }
-        memcpy(temp_row + data_start,
-               values + total_written,
-               data_len);
-        for (int page = 0; page < NVMCTRL_ROW_SIZE / NVMCTRL_PAGE_SIZE; page++) {
-            do {
-                error_code = nvm_write_buffer((uint32_t) self->start_address + row_start + page * NVMCTRL_PAGE_SIZE,
-                                              temp_row + page * NVMCTRL_PAGE_SIZE,
-                                              NVMCTRL_PAGE_SIZE);
-            } while (error_code == STATUS_BUSY);
-            if (error_code != STATUS_OK) {
-                return false;
-            }
-        }
-    }
+        uint32_t start_index, uint8_t* values, uint32_t len) {
+    // We don't use features that use any advanced NVMCTRL features so we can fake the descriptor
+    // whenever we need it instead of storing it long term.
+    struct flash_descriptor desc;
+    desc.dev.hw = NVMCTRL;
+    flash_write(&desc, (uint32_t) self->start_address + start_index, values, len);
     return true;
 }
 
diff --git a/ports/atmel-samd/supervisor/port.c b/ports/atmel-samd/supervisor/port.c
index eafb9b785..963817dbf 100644
--- a/ports/atmel-samd/supervisor/port.c
+++ b/ports/atmel-samd/supervisor/port.c
@@ -147,35 +147,6 @@ safe_mode_t port_init(void) {
         return USER_SAFE_MODE;
     }
 
-    // #if CIRCUITPY_INTERNAL_NVM_SIZE > 0
-    // // Upgrade the nvm flash to include one sector for eeprom emulation.
-    // struct nvm_fusebits fuses;
-    // if (nvm_get_fuses(&fuses) == STATUS_OK &&
-    //         fuses.eeprom_size == NVM_EEPROM_EMULATOR_SIZE_0) {
-    //     #ifdef INTERNAL_FLASH_FS
-    //     // Shift the internal file system up one row.
-    //     for (uint8_t row = 0; row < TOTAL_INTERNAL_FLASH_SIZE / NVMCTRL_ROW_SIZE; row++) {
-    //         uint32_t new_row_address = INTERNAL_FLASH_MEM_SEG1_START_ADDR + row * NVMCTRL_ROW_SIZE;
-    //         nvm_erase_row(new_row_address);
-    //         nvm_write_buffer(new_row_address,
-    //                          (uint8_t*) (new_row_address + CIRCUITPY_INTERNAL_EEPROM_SIZE),
-    //                          NVMCTRL_ROW_SIZE);
-    //     }
-    //     #endif
-    //     uint32_t nvm_size = CIRCUITPY_INTERNAL_NVM_SIZE;
-    //     uint8_t enum_value = 6;
-    //     while (nvm_size > 256 && enum_value != 255) {
-    //         nvm_size /= 2;
-    //         enum_value -= 1;
-    //     }
-    //     if (enum_value != 255 && nvm_size == 256) {
-    //         // Mark the last section as eeprom now.
-    //         fuses.eeprom_size = (enum nvm_eeprom_emulator_size) enum_value;
-    //         nvm_set_fuses(&fuses);
-    //     }
-    // }
-    // #endif
-
     return NO_SAFE_MODE;
 }
 
diff --git a/shared-bindings/nvm/ByteArray.c b/shared-bindings/nvm/ByteArray.c
index f4e046378..8b1782045 100644
--- a/shared-bindings/nvm/ByteArray.c
+++ b/shared-bindings/nvm/ByteArray.c
@@ -36,12 +36,13 @@
 //| ================================================================================
 //|
 //| Non-volatile memory is available as a byte array that persists over reloads
-//| and power cycles.
+//| and power cycles. Each assignment causes an erase and write cycle so its recommended to assign
+//| all values to change at once.
 //|
 //| Usage::
 //|
 //|    import microcontroller
-//|    microcontroller.nvm[0] = 0xcc
+//|    microcontroller.nvm[0:] = b"\xcc\x10\x00"
 //|
 
 //| .. class:: ByteArray()