Merge remote-tracking branch 'origin/main' into update-protomatter-rp2

8 files changed, 263 insertions, 338 deletions

diff --git a/ports/raspberrypi/boards/adafruit_feather_rp2040/board.c b/ports/raspberrypi/boards/adafruit_feather_rp2040/board.c
index 8686f6d0c..c4021a83e 100644
--- a/ports/raspberrypi/boards/adafruit_feather_rp2040/board.c
+++ b/ports/raspberrypi/boards/adafruit_feather_rp2040/board.c
@@ -30,10 +30,6 @@
 #include "src/rp2_common/hardware_gpio/include/hardware/gpio.h"
 
 void board_init(void) {
-    common_hal_never_reset_pin(&pin_GPIO17);
-    gpio_init(17);
-    gpio_set_dir(17, GPIO_OUT);
-    gpio_put(17, true);
 }
 
 bool board_requests_safe_mode(void) {
diff --git a/ports/raspberrypi/boards/adafruit_feather_rp2040/pins.c b/ports/raspberrypi/boards/adafruit_feather_rp2040/pins.c
index 1617ac865..a558d7fe6 100644
--- a/ports/raspberrypi/boards/adafruit_feather_rp2040/pins.c
+++ b/ports/raspberrypi/boards/adafruit_feather_rp2040/pins.c
@@ -14,12 +14,12 @@ STATIC const mp_rom_map_elem_t board_global_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_RX), MP_ROM_PTR(&pin_GPIO1) },
     { MP_ROM_QSTR(MP_QSTR_D1), MP_ROM_PTR(&pin_GPIO0) },
     { MP_ROM_QSTR(MP_QSTR_TX), MP_ROM_PTR(&pin_GPIO0) },
-    { MP_ROM_QSTR(MP_QSTR_D4), MP_ROM_PTR(&pin_GPIO4) },
+    { MP_ROM_QSTR(MP_QSTR_D4), MP_ROM_PTR(&pin_GPIO6) },
 
     { MP_ROM_QSTR(MP_QSTR_SDA), MP_ROM_PTR(&pin_GPIO2) },
     { MP_ROM_QSTR(MP_QSTR_SCL), MP_ROM_PTR(&pin_GPIO3) },
-    { MP_ROM_QSTR(MP_QSTR_D5), MP_ROM_PTR(&pin_GPIO5) },
-    { MP_ROM_QSTR(MP_QSTR_D6), MP_ROM_PTR(&pin_GPIO6) },
+    { MP_ROM_QSTR(MP_QSTR_D5), MP_ROM_PTR(&pin_GPIO7) },
+    { MP_ROM_QSTR(MP_QSTR_D6), MP_ROM_PTR(&pin_GPIO8) },
     { MP_ROM_QSTR(MP_QSTR_D9), MP_ROM_PTR(&pin_GPIO9) },
     { MP_ROM_QSTR(MP_QSTR_D10), MP_ROM_PTR(&pin_GPIO10) },
     { MP_ROM_QSTR(MP_QSTR_D11), MP_ROM_PTR(&pin_GPIO11) },
@@ -27,7 +27,6 @@ STATIC const mp_rom_map_elem_t board_global_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_D13), MP_ROM_PTR(&pin_GPIO13) },
 
     { MP_ROM_QSTR(MP_QSTR_NEOPIXEL), MP_ROM_PTR(&pin_GPIO16) },
-    { MP_ROM_QSTR(MP_QSTR_NEOPIXEL_POWER), MP_ROM_PTR(&pin_GPIO17) },
 
     { MP_ROM_QSTR(MP_QSTR_I2C), MP_ROM_PTR(&board_i2c_obj) },
     { MP_ROM_QSTR(MP_QSTR_SPI), MP_ROM_PTR(&board_spi_obj) },
diff --git a/ports/raspberrypi/common-hal/busio/UART.c b/ports/raspberrypi/common-hal/busio/UART.c
index f9a75b499..1bc121177 100644
--- a/ports/raspberrypi/common-hal/busio/UART.c
+++ b/ports/raspberrypi/common-hal/busio/UART.c
@@ -3,7 +3,7 @@
  *
  * The MIT License (MIT)
  *
- * Copyright (c) 2021 Scott Shawcroft for Adafruit Industries
+ * Copyright (c) 2021 microDev
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -24,238 +24,184 @@
  * THE SOFTWARE.
  */
 
-#include "shared-bindings/microcontroller/__init__.h"
 #include "shared-bindings/busio/UART.h"
 
-#include "mpconfigport.h"
-#include "lib/utils/interrupt_char.h"
-#include "py/gc.h"
+#include "py/stream.h"
 #include "py/mperrno.h"
 #include "py/runtime.h"
-#include "py/stream.h"
-#include "supervisor/shared/translate.h"
 #include "supervisor/shared/tick.h"
+#include "lib/utils/interrupt_char.h"
+#include "common-hal/microcontroller/Pin.h"
 
-#define UART_DEBUG(...) (void)0
-// #define UART_DEBUG(...) mp_printf(&mp_plat_print __VA_OPT__(,) __VA_ARGS__)
-
-// Do-nothing callback needed so that usart_async code will enable rx interrupts.
-// See comment below re usart_async_register_callback()
-// static void usart_async_rxc_callback(const struct usart_async_descriptor *const descr) {
-//     // Nothing needs to be done by us.
-// }
+#include "src/rp2_common/hardware_irq/include/hardware/irq.h"
+#include "src/rp2_common/hardware_gpio/include/hardware/gpio.h"
 
 #define NO_PIN 0xff
 
+#define UART_INST(uart) (((uart) ? uart1 : uart0))
+
+typedef enum {
+    STATUS_FREE = 0,
+    STATUS_BUSY,
+    STATUS_NEVER_RESET
+} uart_status_t;
+
+static uart_status_t uart_status[NUM_UARTS];
+
+void reset_uart(void) {
+    for (uint8_t num = 0; num < NUM_UARTS; num++) {
+        if (uart_status[num] == STATUS_BUSY) {
+            uart_status[num] = STATUS_FREE;
+            uart_deinit(UART_INST(num));
+        }
+    }
+}
+
+void never_reset_uart(uint8_t num) {
+    uart_status[num] = STATUS_NEVER_RESET;
+}
+
+static uint8_t pin_init(const uint8_t uart, const mcu_pin_obj_t * pin, const uint8_t pin_type) {
+    if (pin == NULL) {
+        return NO_PIN;
+    }
+    if (!(((pin->number % 4) == pin_type) && ((((pin->number + 4) / 8) % NUM_UARTS) == uart))) {
+        mp_raise_ValueError(translate("Invalid pins"));
+    }
+    claim_pin(pin);
+    gpio_set_function(pin->number, GPIO_FUNC_UART);
+    return pin->number;
+}
+
+static busio_uart_obj_t* active_uarts[NUM_UARTS];
+
+static void _copy_into_ringbuf(ringbuf_t* r, uart_inst_t* uart) {
+    while (uart_is_readable(uart) && ringbuf_num_empty(r) > 0) {
+        ringbuf_put(r, (uint8_t) uart_get_hw(uart)->dr);
+    }
+}
+
+static void shared_callback(busio_uart_obj_t *self) {
+    _copy_into_ringbuf(&self->ringbuf, self->uart);
+    // We always clear the interrupt so it doesn't continue to fire because we
+    // may not have read everything available.
+    uart_get_hw(self->uart)->icr = UART_UARTICR_RXIC_BITS;
+}
+
+static void uart0_callback(void) {
+    shared_callback(active_uarts[0]);
+}
+
+static void uart1_callback(void) {
+    shared_callback(active_uarts[1]);
+}
+
 void common_hal_busio_uart_construct(busio_uart_obj_t *self,
-    const mcu_pin_obj_t * tx, const mcu_pin_obj_t * rx,
-    const mcu_pin_obj_t * rts, const mcu_pin_obj_t * cts,
-    const mcu_pin_obj_t * rs485_dir, bool rs485_invert,
-    uint32_t baudrate, uint8_t bits, busio_uart_parity_t parity, uint8_t stop,
-    mp_float_t timeout, uint16_t receiver_buffer_size, byte* receiver_buffer,
-    bool sigint_enabled) {
-    mp_raise_NotImplementedError(translate("UART not yet supported"));
-
-//     Sercom* sercom = NULL;
-//     uint8_t sercom_index = 255; // Unset index
-//     uint32_t rx_pinmux = 0;
-//     uint8_t rx_pad = 255; // Unset pad
-//     uint32_t tx_pinmux = 0;
-//     uint8_t tx_pad = 255; // Unset pad
-
-//     if ((rts != NULL) || (cts != NULL) || (rs485_dir != NULL) || (rs485_invert)) {
-//         mp_raise_ValueError(translate("RTS/CTS/RS485 Not yet supported on this device"));
-//     }
-
-//     if (bits > 8) {
-//         mp_raise_NotImplementedError(translate("bytes > 8 bits not supported"));
-//     }
-
-//     bool have_tx = tx != NULL;
-//     bool have_rx = rx != NULL;
-//     if (!have_tx && !have_rx) {
-//         mp_raise_ValueError(translate("tx and rx cannot both be None"));
-//     }
-
-//     self->baudrate = baudrate;
-//     self->character_bits = bits;
-//     self->timeout_ms = timeout * 1000;
-
-//     // This assignment is only here because the usart_async routines take a *const argument.
-//     struct usart_async_descriptor * const usart_desc_p = (struct usart_async_descriptor * const) &self->usart_desc;
-
-//     for (int i = 0; i < NUM_SERCOMS_PER_PIN; i++) {
-//         Sercom* potential_sercom = NULL;
-//         if (have_tx) {
-//             sercom_index = tx->sercom[i].index;
-//             if (sercom_index >= SERCOM_INST_NUM) {
-//                 continue;
-//             }
-//             potential_sercom = sercom_insts[sercom_index];
-// #ifdef SAMD21
-// 	    if (potential_sercom->USART.CTRLA.bit.ENABLE != 0 ||
-//                 !(tx->sercom[i].pad == 0 ||
-//                   tx->sercom[i].pad == 2)) {
-//                 continue;
-//             }
-// #endif
-// #ifdef SAM_D5X_E5X
-// 	    if (potential_sercom->USART.CTRLA.bit.ENABLE != 0 ||
-//                 !(tx->sercom[i].pad == 0)) {
-//                 continue;
-//             }
-// #endif
-//             tx_pinmux = PINMUX(tx->number, (i == 0) ? MUX_C : MUX_D);
-//             tx_pad = tx->sercom[i].pad;
-//             if (rx == NULL) {
-//                 sercom = potential_sercom;
-//                 break;
-//             }
-//         }
-//         for (int j = 0; j < NUM_SERCOMS_PER_PIN; j++) {
-//             if (((!have_tx && rx->sercom[j].index < SERCOM_INST_NUM &&
-//                   sercom_insts[rx->sercom[j].index]->USART.CTRLA.bit.ENABLE == 0) ||
-//                  sercom_index == rx->sercom[j].index) &&
-//                 rx->sercom[j].pad != tx_pad) {
-//                 rx_pinmux = PINMUX(rx->number, (j == 0) ? MUX_C : MUX_D);
-//                 rx_pad = rx->sercom[j].pad;
-//                 sercom = sercom_insts[rx->sercom[j].index];
-//                 sercom_index = rx->sercom[j].index;
-//                 break;
-//             }
-//         }
-//         if (sercom != NULL) {
-//             break;
-//         }
-//     }
-//     if (sercom == NULL) {
-//         mp_raise_ValueError(translate("Invalid pins"));
-//     }
-//     if (!have_tx) {
-//         tx_pad = 0;
-//         if (rx_pad == 0) {
-//             tx_pad = 2;
-//         }
-//     }
-//     if (!have_rx) {
-//         rx_pad = (tx_pad + 1) % 4;
-//     }
-
-//     // Set up clocks on SERCOM.
-//     samd_peripherals_sercom_clock_init(sercom, sercom_index);
-
-//     if (rx && receiver_buffer_size > 0) {
-//         self->buffer_length = receiver_buffer_size;
-//         // Initially allocate the UART's buffer in the long-lived part of the
-//         // heap.  UARTs are generally long-lived objects, but the "make long-
-//         // lived" machinery is incapable of moving internal pointers like
-//         // self->buffer, so do it manually.  (However, as long as internal
-//         // pointers like this are NOT moved, allocating the buffer
-//         // in the long-lived pool is not strictly necessary)
-//         self->buffer = (uint8_t *) gc_alloc(self->buffer_length * sizeof(uint8_t), false, true);
-//         if (self->buffer == NULL) {
-//             common_hal_busio_uart_deinit(self);
-//             mp_raise_msg_varg(&mp_type_MemoryError, translate("Failed to allocate RX buffer of %d bytes"), self->buffer_length * sizeof(uint8_t));
-//         }
-//     } else {
-//         self->buffer_length = 0;
-//         self->buffer = NULL;
-//     }
-
-//     if (usart_async_init(usart_desc_p, sercom, self->buffer, self->buffer_length, NULL) != ERR_NONE) {
-//         mp_raise_ValueError(translate("Could not initialize UART"));
-//     }
-
-//     // usart_async_init() sets a number of defaults based on a prototypical SERCOM
-//     // which don't necessarily match what we need. After calling it, set the values
-//     // specific to this instantiation of UART.
-
-//     // Set pads computed for this SERCOM.
-//     // TXPO:
-//     // 0x0: TX pad 0; no RTS/CTS
-//     // 0x1: TX pad 2; no RTS/CTS
-//     // 0x2: TX pad 0; RTS: pad 2, CTS: pad 3 (not used by us right now)
-//     // So divide by 2 to map pad to value.
-//     // RXPO:
-//     // 0x0: RX pad 0
-//     // 0x1: RX pad 1
-//     // 0x2: RX pad 2
-//     // 0x3: RX pad 3
-
-//     // Doing a group mask and set of the registers saves 60 bytes over setting the bitfields individually.
-
-//     sercom->USART.CTRLA.reg &= ~(SERCOM_USART_CTRLA_TXPO_Msk |
-//                                  SERCOM_USART_CTRLA_RXPO_Msk |
-//                                  SERCOM_USART_CTRLA_FORM_Msk);
-//     sercom->USART.CTRLA.reg |= SERCOM_USART_CTRLA_TXPO(tx_pad / 2) |
-//                                SERCOM_USART_CTRLA_RXPO(rx_pad) |
-//                                (parity == BUSIO_UART_PARITY_NONE ? 0 : SERCOM_USART_CTRLA_FORM(1));
-
-//     // Enable tx and/or rx based on whether the pins were specified.
-//     // CHSIZE is 0 for 8 bits, 5, 6, 7 for 5, 6, 7 bits. 1 for 9 bits, but we don't support that.
-//     sercom->USART.CTRLB.reg &= ~(SERCOM_USART_CTRLB_TXEN |
-//                                  SERCOM_USART_CTRLB_RXEN |
-//                                  SERCOM_USART_CTRLB_PMODE |
-//                                  SERCOM_USART_CTRLB_SBMODE |
-//                                  SERCOM_USART_CTRLB_CHSIZE_Msk);
-//     sercom->USART.CTRLB.reg |= (have_tx ? SERCOM_USART_CTRLB_TXEN : 0) |
-//                                (have_rx ? SERCOM_USART_CTRLB_RXEN : 0) |
-//                                (parity == BUSIO_UART_PARITY_ODD ? SERCOM_USART_CTRLB_PMODE : 0) |
-//                                (stop > 1 ? SERCOM_USART_CTRLB_SBMODE : 0) |
-//                                SERCOM_USART_CTRLB_CHSIZE(bits % 8);
-
-//     // Set baud rate
-//     common_hal_busio_uart_set_baudrate(self, baudrate);
-
-//     // Turn on rx interrupt handling. The UART async driver has its own set of internal callbacks,
-//     // which are set up by uart_async_init(). These in turn can call user-specified callbacks.
-//     // In fact, the actual interrupts are not enabled unless we set up a user-specified callback.
-//     // This is confusing. It's explained in the Atmel START User Guide -> Implementation Description ->
-//     // Different read function behavior in some asynchronous drivers. As of this writing:
-//     // http://start.atmel.com/static/help/index.html?GUID-79201A5A-226F-4FBB-B0B8-AB0BE0554836
-//     // Look at the ASFv4 code example for async USART.
-//     usart_async_register_callback(usart_desc_p, USART_ASYNC_RXC_CB, usart_async_rxc_callback);
-
-
-//     if (have_tx) {
-//         gpio_set_pin_direction(tx->number, GPIO_DIRECTION_OUT);
-//         gpio_set_pin_pull_mode(tx->number, GPIO_PULL_OFF);
-//         gpio_set_pin_function(tx->number, tx_pinmux);
-//         self->tx_pin  = tx->number;
-//         claim_pin(tx);
-//     } else {
-//         self->tx_pin = NO_PIN;
-//     }
-
-//     if (have_rx) {
-//         gpio_set_pin_direction(rx->number, GPIO_DIRECTION_IN);
-//         gpio_set_pin_pull_mode(rx->number, GPIO_PULL_OFF);
-//         gpio_set_pin_function(rx->number, rx_pinmux);
-//         self->rx_pin  = rx->number;
-//         claim_pin(rx);
-//     } else {
-//         self->rx_pin = NO_PIN;
-//     }
-
-//     usart_async_enable(usart_desc_p);
+        const mcu_pin_obj_t * tx, const mcu_pin_obj_t * rx,
+        const mcu_pin_obj_t * rts, const mcu_pin_obj_t * cts,
+        const mcu_pin_obj_t * rs485_dir, bool rs485_invert,
+        uint32_t baudrate, uint8_t bits, busio_uart_parity_t parity, uint8_t stop,
+        mp_float_t timeout, uint16_t receiver_buffer_size, byte* receiver_buffer,
+        bool sigint_enabled) {
+
+    if (bits > 8) {
+        mp_raise_ValueError(translate("Invalid word/bit length"));
+    }
+
+    if (receiver_buffer_size == 0) {
+        mp_raise_ValueError(translate("Invalid buffer size"));
+    }
+
+    if ((rs485_dir != NULL) || (rs485_invert)) {
+        mp_raise_NotImplementedError(translate("RS485 Not yet supported on this device"));
+    }
+
+    uint8_t uart_id = ((((tx != NULL) ? tx->number : rx->number) + 4) / 8) % NUM_UARTS;
+
+    if (uart_status[uart_id] != STATUS_FREE) {
+        mp_raise_RuntimeError(translate("All UART peripherals are in use"));
+    } else {
+        uart_status[uart_id] = STATUS_BUSY;
+    }
+
+    self->tx_pin = pin_init(uart_id, tx, 0);
+    self->rx_pin = pin_init(uart_id, rx, 1);
+    self->cts_pin = pin_init(uart_id, cts, 2);
+    self->rts_pin = pin_init(uart_id, rts, 3);
+
+    self->uart = UART_INST(uart_id);
+    self->uart_id = uart_id;
+    self->baudrate = baudrate;
+    self->timeout_ms = timeout * 1000;
+
+    uart_init(self->uart, self->baudrate);
+    uart_set_fifo_enabled(self->uart, true);
+    uart_set_format(self->uart, bits, stop, parity);
+    uart_set_hw_flow(self->uart, (cts != NULL), (rts != NULL));
+
+    if (rx != NULL) {
+        // Initially allocate the UART's buffer in the long-lived part of the
+        // heap. UARTs are generally long-lived objects, but the "make long-
+        // lived" machinery is incapable of moving internal pointers like
+        // self->buffer, so do it manually.  (However, as long as internal
+        // pointers like this are NOT moved, allocating the buffer
+        // in the long-lived pool is not strictly necessary)
+        // (This is a macro.)
+        if (!ringbuf_alloc(&self->ringbuf, receiver_buffer_size, true)) {
+            mp_raise_msg(&mp_type_MemoryError, translate("Failed to allocate RX buffer"));
+        }
+        active_uarts[uart_id] = self;
+        if (uart_id == 1) {
+            self->uart_irq_id = UART1_IRQ;
+            irq_set_exclusive_handler(self->uart_irq_id, uart1_callback);
+        } else {
+            self->uart_irq_id = UART0_IRQ;
+            irq_set_exclusive_handler(self->uart_irq_id, uart0_callback);
+        }
+        irq_set_enabled(self->uart_irq_id, true);
+        uart_set_irq_enables(self->uart, true /* rx has data */, false /* tx needs data */);
+    }
 }
 
 bool common_hal_busio_uart_deinited(busio_uart_obj_t *self) {
-    return self->rx_pin == NO_PIN && self->tx_pin == NO_PIN;
+    return self->tx_pin == NO_PIN && self->rx_pin == NO_PIN;
 }
 
 void common_hal_busio_uart_deinit(busio_uart_obj_t *self) {
     if (common_hal_busio_uart_deinited(self)) {
         return;
     }
-    // This assignment is only here because the usart_async routines take a *const argument.
-    // struct usart_async_descriptor * const usart_desc_p = (struct usart_async_descriptor * const) &self->usart_desc;
-    // usart_async_disable(usart_desc_p);
-    // usart_async_deinit(usart_desc_p);
-    reset_pin_number(self->rx_pin);
+    uart_deinit(self->uart);
+    ringbuf_free(&self->ringbuf);
+    active_uarts[self->uart_id] = NULL;
+    uart_status[self->uart_id] = STATUS_FREE;
     reset_pin_number(self->tx_pin);
-    self->rx_pin = NO_PIN;
+    reset_pin_number(self->rx_pin);
+    reset_pin_number(self->cts_pin);
+    reset_pin_number(self->rts_pin);
     self->tx_pin = NO_PIN;
+    self->rx_pin = NO_PIN;
+    self->cts_pin = NO_PIN;
+    self->rts_pin = NO_PIN;
+}
+
+// Write characters.
+size_t common_hal_busio_uart_write(busio_uart_obj_t *self, const uint8_t *data, size_t len, int *errcode) {
+    if (self->tx_pin == NO_PIN) {
+        mp_raise_ValueError(translate("No TX pin"));
+    }
+
+    while (len > 0) {
+        while (uart_is_writable(self->uart) && len > 0) {
+            // Write and advance.
+            uart_get_hw(self->uart)->dr = *data++;
+            // Decrease how many chars left to write.
+            len--;
+        }
+        RUN_BACKGROUND_TASKS;
+    }
+
+    return len;
 }
 
 // Read characters.
@@ -264,87 +210,56 @@ size_t common_hal_busio_uart_read(busio_uart_obj_t *self, uint8_t *data, size_t
         mp_raise_ValueError(translate("No RX pin"));
     }
 
-    // This assignment is only here because the usart_async routines take a *const argument.
-    // struct usart_async_descriptor * const usart_desc_p = (struct usart_async_descriptor * const) &self->usart_desc;
-
     if (len == 0) {
         // Nothing to read.
         return 0;
     }
 
-    // struct io_descriptor *io;
-    // usart_async_get_io_descriptor(usart_desc_p, &io);
-
-    size_t total_read = 0;
-    // uint64_t start_ticks = supervisor_ticks_ms64();
-
-    // // Busy-wait until timeout or until we've read enough chars.
-    // while (supervisor_ticks_ms64() - start_ticks <= self->timeout_ms) {
-    //     // Read as many chars as we can right now, up to len.
-    //     size_t num_read = io_read(io, data, len);
-
-    //     // Advance pointer in data buffer, and decrease how many chars left to read.
-    //     data += num_read;
-    //     len -= num_read;
-    //     total_read += num_read;
-    //     if (len == 0) {
-    //         // Don't need to read any more: data buf is full.
-    //         break;
-    //     }
-    //     if (num_read > 0) {
-    //         // Reset the timeout on every character read.
-    //         start_ticks = supervisor_ticks_ms64();
-    //     }
-    //     RUN_BACKGROUND_TASKS;
-    //     // Allow user to break out of a timeout with a KeyboardInterrupt.
-    //     if (mp_hal_is_interrupted()) {
-    //         break;
-    //     }
-    //     // If we are zero timeout, make sure we don't loop again (in the event
-    //     // we read in under 1ms)
-    //     if (self->timeout_ms == 0) {
-    //         break;
-    //     }
-    // }
-
-    // if (total_read == 0) {
-    //     *errcode = EAGAIN;
-    //     return MP_STREAM_ERROR;
-    // }
+    // Prevent conflict with uart irq.
+    irq_set_enabled(self->uart_irq_id, false);
+
+    // Copy as much received data as available, up to len bytes.
+    size_t total_read = ringbuf_get_n(&self->ringbuf, data, len);
+
+    // Check if we still need to read more data.
+    if (len > total_read) {
+        len-=total_read;
+        uint64_t start_ticks = supervisor_ticks_ms64();
+        // Busy-wait until timeout or until we've read enough chars.
+        while (len > 0 && (supervisor_ticks_ms64() - start_ticks < self->timeout_ms)) {
+            if (uart_is_readable(self->uart)) {
+                // Read and advance.
+                data[total_read] = uart_get_hw(self->uart)->dr;
+
+                // Adjust the counters.
+                len--;
+                total_read++;
+
+                // Reset the timeout on every character read.
+                start_ticks = supervisor_ticks_ms64();
+            }
+            RUN_BACKGROUND_TASKS;
+            // Allow user to break out of a timeout with a KeyboardInterrupt.
+            if (mp_hal_is_interrupted()) {
+                break;
+            }
+        }
+    }
 
-    return total_read;
-}
+    // Now that we've emptied the ringbuf some, fill it up with anything in the
+    // FIFO. This ensures that we'll empty the FIFO as much as possible and
+    // reset the interrupt when we catch up.
+    _copy_into_ringbuf(&self->ringbuf, self->uart);
 
-// Write characters.
-size_t common_hal_busio_uart_write(busio_uart_obj_t *self, const uint8_t *data, size_t len, int *errcode) {
-    if (self->tx_pin == NO_PIN) {
-        mp_raise_ValueError(translate("No TX pin"));
-    }
+    // Re-enable irq.
+    irq_set_enabled(self->uart_irq_id, true);
 
-    // This assignment is only here because the usart_async routines take a *const argument.
-    // struct usart_async_descriptor * const usart_desc_p = (struct usart_async_descriptor * const) &self->usart_desc;
-
-    // struct io_descriptor *io;
-    // usart_async_get_io_descriptor(usart_desc_p, &io);
-
-    // // Start writing characters. This is non-blocking and will
-    // // return immediately after setting up the write.
-    // if (io_write(io, data, len) < 0) {
-    //     *errcode = MP_EAGAIN;
-    //     return MP_STREAM_ERROR;
-    // }
-
-    // // Busy-wait until all characters transmitted.
-    // struct usart_async_status async_status;
-    // while (true) {
-    //     usart_async_get_status(usart_desc_p, &async_status);
-    //     if (async_status.txcnt >= len) {
-    //         break;
-    //     }
-    //     RUN_BACKGROUND_TASKS;
-    // }
+    if (total_read == 0) {
+        *errcode = EAGAIN;
+        return MP_STREAM_ERROR;
+    }
 
-    return len;
+    return total_read;
 }
 
 uint32_t common_hal_busio_uart_get_baudrate(busio_uart_obj_t *self) {
@@ -352,18 +267,8 @@ uint32_t common_hal_busio_uart_get_baudrate(busio_uart_obj_t *self) {
 }
 
 void common_hal_busio_uart_set_baudrate(busio_uart_obj_t *self, uint32_t baudrate) {
-    // This assignment is only here because the usart_async routines take a *const argument.
-    // struct usart_async_descriptor * const usart_desc_p = (struct usart_async_descriptor * const) &self->usart_desc;
-    // usart_async_set_baud_rate(usart_desc_p,
-    //                           // Samples and ARITHMETIC vs FRACTIONAL must correspond to USART_SAMPR in
-    //                           // hpl_sercom_config.h.
-    //                           _usart_async_calculate_baud_rate(baudrate,  // e.g. 9600 baud
-    //                                                            PROTOTYPE_SERCOM_USART_ASYNC_CLOCK_FREQUENCY,
-    //                                                            16,   // samples
-    //                                                            USART_BAUDRATE_ASYNCH_ARITHMETIC,
-    //                                                            0  // fraction - not used for ARITHMETIC
-    //                                                            ));
     self->baudrate = baudrate;
+    uart_set_baudrate(self->uart, baudrate);
 }
 
 mp_float_t common_hal_busio_uart_get_timeout(busio_uart_obj_t *self) {
@@ -375,30 +280,30 @@ void common_hal_busio_uart_set_timeout(busio_uart_obj_t *self, mp_float_t timeou
 }
 
 uint32_t common_hal_busio_uart_rx_characters_available(busio_uart_obj_t *self) {
-    // This assignment is only here because the usart_async routines take a *const argument.
-    // struct usart_async_descriptor * const usart_desc_p = (struct usart_async_descriptor * const) &self->usart_desc;
-    // struct usart_async_status async_status;
-    // usart_async_get_status(usart_desc_p, &async_status);
-    // return async_status.rxcnt;
-    return 0;
+    // Prevent conflict with uart irq.
+    irq_set_enabled(self->uart_irq_id, false);
+    // The UART only interrupts after a threshold so make sure to copy anything
+    // out of its FIFO before measuring how many bytes we've received.
+    _copy_into_ringbuf(&self->ringbuf, self->uart);
+    irq_set_enabled(self->uart_irq_id, false);
+    return ringbuf_num_filled(&self->ringbuf);
 }
 
 void common_hal_busio_uart_clear_rx_buffer(busio_uart_obj_t *self) {
-    // This assignment is only here because the usart_async routines take a *const argument.
-    // struct usart_async_descriptor * const usart_desc_p = (struct usart_async_descriptor * const) &self->usart_desc;
-    // usart_async_flush_rx_buffer(usart_desc_p);
+    // Prevent conflict with uart irq.
+    irq_set_enabled(self->uart_irq_id, false);
+    ringbuf_clear(&self->ringbuf);
 
+    // Throw away the FIFO contents too.
+    while (uart_is_readable(self->uart)) {
+        (void) uart_get_hw(self->uart)->dr;
+    }
+    irq_set_enabled(self->uart_irq_id, true);
 }
 
-// True if there are no characters still to be written.
 bool common_hal_busio_uart_ready_to_tx(busio_uart_obj_t *self) {
     if (self->tx_pin == NO_PIN) {
         return false;
     }
-    return false;
-    // // This assignment is only here because the usart_async routines take a *const argument.
-    // struct usart_async_descriptor * const usart_desc_p = (struct usart_async_descriptor * const) &self->usart_desc;
-    // struct usart_async_status async_status;
-    // usart_async_get_status(usart_desc_p, &async_status);
-    // return !(async_status.flags & USART_ASYNC_STATUS_BUSY);
+    return uart_is_writable(self->uart);
 }
diff --git a/ports/raspberrypi/common-hal/busio/UART.h b/ports/raspberrypi/common-hal/busio/UART.h
index 43ed9bee0..4c07de240 100644
--- a/ports/raspberrypi/common-hal/busio/UART.h
+++ b/ports/raspberrypi/common-hal/busio/UART.h
@@ -3,7 +3,7 @@
  *
  * The MIT License (MIT)
  *
- * Copyright (c) 2021 Scott Shawcroft for Adafruit Industries
+ * Copyright (c) 2021 microDev
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -27,21 +27,26 @@
 #ifndef MICROPY_INCLUDED_RASPBERRYPI_COMMON_HAL_BUSIO_UART_H
 #define MICROPY_INCLUDED_RASPBERRYPI_COMMON_HAL_BUSIO_UART_H
 
-#include "common-hal/microcontroller/Pin.h"
-
 #include "py/obj.h"
+#include "py/ringbuf.h"
+
+#include "src/rp2_common/hardware_uart/include/hardware/uart.h"
 
 typedef struct {
     mp_obj_base_t base;
-    // struct usart_async_descriptor usart_desc;
-    uint8_t rx_pin;
     uint8_t tx_pin;
-    uint8_t character_bits;
-    bool rx_error;
+    uint8_t rx_pin;
+    uint8_t cts_pin;
+    uint8_t rts_pin;
+    uint8_t uart_id;
+    uint8_t uart_irq_id;
     uint32_t baudrate;
     uint32_t timeout_ms;
-    uint32_t buffer_length;
-    uint8_t* buffer;
+    uart_inst_t * uart;
+    ringbuf_t ringbuf;
 } busio_uart_obj_t;
 
+extern void reset_uart(void);
+extern void never_reset_uart(uint8_t num);
+
 #endif // MICROPY_INCLUDED_RASPBERRYPI_COMMON_HAL_BUSIO_UART_H
diff --git a/ports/raspberrypi/common-hal/digitalio/DigitalInOut.c b/ports/raspberrypi/common-hal/digitalio/DigitalInOut.c
index b0bc1b96e..a1a23b9ab 100644
--- a/ports/raspberrypi/common-hal/digitalio/DigitalInOut.c
+++ b/ports/raspberrypi/common-hal/digitalio/DigitalInOut.c
@@ -43,6 +43,7 @@ digitalinout_result_t common_hal_digitalio_digitalinout_construct(
     self->output = false;
     self->open_drain = false;
 
+    // Set to input. No output value.
     gpio_init(pin->number);
     return DIGITALINOUT_OK;
 }
@@ -75,11 +76,17 @@ digitalinout_result_t common_hal_digitalio_digitalinout_switch_to_output(
         digitalio_digitalinout_obj_t* self, bool value,
         digitalio_drive_mode_t drive_mode) {
     const uint8_t pin = self->pin->number;
-    gpio_set_dir(pin, GPIO_OUT);
-    // TODO: Turn on "strong" pin driving (more current available).
+    gpio_disable_pulls(pin);
+
+    // Turn on "strong" pin driving (more current available).
+    hw_write_masked(&padsbank0_hw->io[pin],
+                    PADS_BANK0_GPIO0_DRIVE_VALUE_12MA << PADS_BANK0_GPIO0_DRIVE_LSB,
+                    PADS_BANK0_GPIO0_DRIVE_BITS);
 
     self->output = true;
-    common_hal_digitalio_digitalinout_set_drive_mode(self, drive_mode);
+    self->open_drain = drive_mode == DRIVE_MODE_OPEN_DRAIN;
+
+    // Pin direction is ultimately set in set_value. We don't need to do it here.
     common_hal_digitalio_digitalinout_set_value(self, value);
     return DIGITALINOUT_OK;
 }
@@ -92,10 +99,18 @@ digitalio_direction_t common_hal_digitalio_digitalinout_get_direction(
 void common_hal_digitalio_digitalinout_set_value(
         digitalio_digitalinout_obj_t* self, bool value) {
     const uint8_t pin = self->pin->number;
-    if (self->open_drain) {
-        gpio_set_dir(pin, value ? GPIO_IN : GPIO_OUT);
+    if (self->open_drain && value) {
+        // If true and open-drain, set the direction -before- setting
+        // the pin value, to to avoid a high glitch on the pin before
+        // switching from output to input for open-drain.
+        gpio_set_dir(pin, GPIO_IN);
+        gpio_put(pin, value);
     } else {
+        // Otherwise set the direction -after- setting the pin value,
+        // to avoid a glitch which might occur if the old value was
+        // different and the pin was previously set to input.
         gpio_put(pin, value);
+        gpio_set_dir(pin, GPIO_OUT);
     }
 }
 
@@ -110,9 +125,6 @@ digitalinout_result_t common_hal_digitalio_digitalinout_set_drive_mode(
     const uint8_t pin = self->pin->number;
     bool value = common_hal_digitalio_digitalinout_get_value(self);
     self->open_drain = drive_mode == DRIVE_MODE_OPEN_DRAIN;
-    if (self->open_drain) {
-        gpio_put(pin, false);
-    }
     // True is implemented differently between modes so reset the value to make
     // sure it's correct for the new mode.
     if (value) {
diff --git a/ports/raspberrypi/common-hal/pwmio/PWMOut.c b/ports/raspberrypi/common-hal/pwmio/PWMOut.c
index f83da3014..9ca31a35e 100644
--- a/ports/raspberrypi/common-hal/pwmio/PWMOut.c
+++ b/ports/raspberrypi/common-hal/pwmio/PWMOut.c
@@ -162,6 +162,7 @@ pwmout_result_t common_hal_pwmio_pwmout_construct(pwmio_pwmout_obj_t* self,
         common_hal_pwmio_pwmout_set_frequency(self, frequency);
         pwm_set_enabled(slice, true);
     } else {
+        common_hal_pwmio_pwmout_set_frequency(self, frequency);
         common_hal_pwmio_pwmout_set_duty_cycle(self, duty);
     }
 
@@ -179,7 +180,7 @@ void pwmout_free(uint8_t slice, uint8_t channel) {
     uint32_t channel_mask = _mask(slice, channel);
     channel_use &= ~channel_mask;
     never_reset_channel &= ~channel_mask;
-    uint32_t slice_mask = ((1 << CHANNELS_PER_SLICE) - 1) << (slice * CHANNELS_PER_SLICE + channel);
+    uint32_t slice_mask = ((1 << CHANNELS_PER_SLICE) - 1) << (slice * CHANNELS_PER_SLICE);
     if ((channel_use & slice_mask) == 0) {
         target_slice_frequencies[slice] = 0;
         slice_variable_frequency &= ~(1 << slice);
diff --git a/ports/raspberrypi/common-hal/rp2pio/StateMachine.c b/ports/raspberrypi/common-hal/rp2pio/StateMachine.c
index 7d2385064..5625a1b29 100644
--- a/ports/raspberrypi/common-hal/rp2pio/StateMachine.c
+++ b/ports/raspberrypi/common-hal/rp2pio/StateMachine.c
@@ -426,7 +426,7 @@ void common_hal_rp2pio_statemachine_construct(rp2pio_statemachine_obj_t *self,
         mp_raise_ValueError(translate("Initial set pin state conflicts with initial out pin state"));
     }
     if ((initial_pin_direction & set_out_overlap) != (initial_set_pin_direction & set_out_overlap)) {
-        mp_raise_ValueError(translate("Initial set pin direcion conflicts with initial out pin direction"));
+        mp_raise_ValueError(translate("Initial set pin direction conflicts with initial out pin direction"));
     }
     initial_pin_state |= initial_set_pin_state;
     initial_pin_direction |= initial_set_pin_direction;
diff --git a/ports/raspberrypi/supervisor/port.c b/ports/raspberrypi/supervisor/port.c
index 10651d36b..501a0c5ce 100644
--- a/ports/raspberrypi/supervisor/port.c
+++ b/ports/raspberrypi/supervisor/port.c
@@ -39,6 +39,9 @@
 #include "shared-bindings/rtc/__init__.h"
 #include "shared-bindings/pwmio/PWMOut.h"
 
+#include "common-hal/rtc/RTC.h"
+#include "common-hal/busio/UART.h"
+
 #include "supervisor/shared/safe_mode.h"
 #include "supervisor/shared/stack.h"
 #include "supervisor/shared/tick.h"
@@ -78,6 +81,9 @@ safe_mode_t port_init(void) {
     // Reset everything into a known state before board_init.
     reset_port();
 
+    // Initialize RTC
+    common_hal_rtc_init();
+
     // For the tick.
     hardware_alarm_claim(0);
     hardware_alarm_set_callback(0, _tick_callback);
@@ -95,6 +101,7 @@ void reset_port(void) {
     #if CIRCUITPY_BUSIO
     reset_i2c();
     reset_spi();
+    reset_uart();
     #endif
 
     #if CIRCUITPY_PWMIO