samd/machine_uart: Add the machine.UART class.

All board pins that have UART's assigned can be used.  Baud rate range is
75 Baud to ~2 MBaud.

No flow control yet, and only RX is buffered.  TX buffer and flow control
may be added later for SAMD51 with its larger RAM and Flash.

ports/samd/Makefile

@@ -93,6 +93,7 @@ SRC_C = \
 	machine_adc.c \
 	machine_led.c \
 	machine_pin.c \
+	machine_uart.c \
 	main.c \
 	modutime.c \
 	modmachine.c \
@@ -144,6 +145,7 @@ SRC_QSTR += \
 	machine_led.c \
 	machine_pin.c \
 	machine_pwm.c \
+	machine_uart.c \
 	modutime.c \
 	modmachine.c \
 	modsamd.c \

ports/samd/machine_uart.c

@@ -0,0 +1,475 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2020-2021 Damien P. George
+ * Copyright (c) 2022 Robert Hammelrath
+ *
+ * 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 "py/runtime.h"
+#include "py/mphal.h"
+#include "py/stream.h"
+#include "py/ringbuf.h"
+#include "modmachine.h"
+#include "samd_soc.h"
+#include "pin_af.h"
+#include "clock_config.h"
+
+#define DEFAULT_UART_BAUDRATE (115200)
+#define DEFAULT_BUFFER_SIZE (256)
+#define MIN_BUFFER_SIZE  (32)
+#define MAX_BUFFER_SIZE  (32766)
+#define USART_BUFFER_TX  (0)
+
+typedef struct _machine_uart_obj_t {
+    mp_obj_base_t base;
+    uint8_t id;
+    uint32_t baudrate;
+    uint8_t bits;
+    uint8_t parity;
+    uint8_t stop;
+    uint8_t tx;
+    sercom_pad_config_t tx_pad_config;
+    uint8_t rx;
+    sercom_pad_config_t rx_pad_config;
+    uint16_t timeout;       // timeout waiting for first char (in ms)
+    uint16_t timeout_char;  // timeout waiting between chars (in ms)
+    bool new;
+    ringbuf_t read_buffer;
+    #if USART_BUFFER_TX
+    ringbuf_t write_buffer;
+    #endif
+} machine_uart_obj_t;
+
+Sercom *sercom_instance[] = SERCOM_INSTS;
+machine_uart_obj_t *uart_table[SERCOM_INST_NUM] = {};
+
+STATIC const char *_parity_name[] = {"None", "", "0", "1"};  // Is defined as 0, 2, 3
+
+// Irq handler
+
+// take all bytes from the fifo and store them in the buffer
+STATIC void uart_drain_rx_fifo(machine_uart_obj_t *self, Sercom *uart) {
+    while (uart->USART.INTFLAG.bit.RXC != 0) {
+        if (ringbuf_free(&self->read_buffer) > 0) {
+            // get a byte from uart and put into the buffer
+            ringbuf_put(&(self->read_buffer), uart->USART.DATA.bit.DATA);
+        } else {
+            // if the buffer is full, discard the data for now
+            // t.b.d.: flow control
+            uint32_t temp;
+            (void)temp;
+            temp = uart->USART.DATA.bit.DATA;
+        }
+    }
+}
+
+void common_uart_irq_handler(int uart_id) {
+    machine_uart_obj_t *self = uart_table[uart_id];
+    // Handle IRQ
+    if (self != NULL) {
+        Sercom *uart = sercom_instance[self->id];
+        if (uart->USART.INTFLAG.bit.RXC != 0) {
+            // Now handler the incoming data
+            uart_drain_rx_fifo(self, uart);
+        } else if (uart->USART.INTFLAG.bit.DRE != 0) {
+            // handle the outgoing data
+        } else {
+            // Disable the other interrupts, if set by error
+            uart->USART.INTENCLR.reg = (uint8_t) ~(SERCOM_USART_INTENCLR_DRE | SERCOM_USART_INTENCLR_RXC);
+        }
+    }
+}
+
+void sercom_enable(Sercom *uart, int state) {
+    uart->USART.CTRLA.bit.ENABLE = state; // Set the state on/off
+    // Wait for the Registers to update.
+    while (uart->USART.SYNCBUSY.bit.ENABLE) {
+    }
+}
+
+STATIC void machine_uart_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
+    machine_uart_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    mp_printf(print, "UART(%u, baudrate=%u, bits=%u, parity=%s, stop=%u, "
+        "timeout=%u, timeout_char=%u, rxbuf=%d)",
+        self->id, self->baudrate, self->bits, _parity_name[self->parity],
+        self->stop + 1, self->timeout, self->timeout_char, self->read_buffer.size - 1);
+}
+
+STATIC mp_obj_t machine_uart_init_helper(machine_uart_obj_t *self, size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    enum { ARG_baudrate, ARG_bits, ARG_parity, ARG_stop, ARG_tx, ARG_rx,
+           ARG_timeout, ARG_timeout_char, ARG_rxbuf, ARG_txbuf};
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_baudrate, MP_ARG_INT, {.u_int = -1} },
+        { MP_QSTR_bits, MP_ARG_INT, {.u_int = -1} },
+        { MP_QSTR_parity, MP_ARG_OBJ, {.u_rom_obj = MP_ROM_INT(-1)} },
+        { MP_QSTR_stop, MP_ARG_INT, {.u_int = -1} },
+        { MP_QSTR_tx, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
+        { MP_QSTR_rx, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
+        { MP_QSTR_timeout, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
+        { MP_QSTR_timeout_char, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
+        { MP_QSTR_rxbuf, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
+        #if USART_BUFFER_TX
+        { MP_QSTR_txbuf, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
+        #endif
+    };
+
+    // Parse args
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+
+    // Set baudrate if configured.
+    if (args[ARG_baudrate].u_int > 0) {
+        self->baudrate = args[ARG_baudrate].u_int;
+    }
+
+    // Set bits if configured.
+    if (args[ARG_bits].u_int > 0) {
+        self->bits = args[ARG_bits].u_int;
+    }
+
+    // Set parity if configured.
+    if (args[ARG_parity].u_obj != MP_OBJ_NEW_SMALL_INT(-1)) {
+        if (args[ARG_parity].u_obj == mp_const_none) {
+            self->parity = 0;
+        } else if (mp_obj_get_int(args[ARG_parity].u_obj) & 1) {
+            self->parity = 1;  // odd
+        } else {
+            self->parity = 2;  // even
+        }
+    }
+
+    // Set stop bits if configured.
+    if (args[ARG_stop].u_int > 0) {
+        self->stop = (args[ARG_stop].u_int - 1) & 1;
+    }
+
+    // Set TX/RX pins if configured.
+    if (args[ARG_tx].u_obj != mp_const_none) {
+        self->tx = mp_hal_get_pin_obj(args[ARG_tx].u_obj);
+    }
+    if (args[ARG_rx].u_obj != mp_const_none) {
+        self->rx = mp_hal_get_pin_obj(args[ARG_rx].u_obj);
+    }
+
+    // Set timeout if configured.
+    if (args[ARG_timeout].u_int >= 0) {
+        self->timeout = args[ARG_timeout].u_int;
+    }
+
+    // Set timeout_char if configured.
+    if (args[ARG_timeout_char].u_int >= 0) {
+        self->timeout_char = args[ARG_timeout_char].u_int;
+    }
+
+    // Set the RX buffer size if configured.
+    size_t rxbuf_len = DEFAULT_BUFFER_SIZE;
+    if (args[ARG_rxbuf].u_int > 0) {
+        rxbuf_len = args[ARG_rxbuf].u_int;
+        if (rxbuf_len < MIN_BUFFER_SIZE) {
+            rxbuf_len = MIN_BUFFER_SIZE;
+        } else if (rxbuf_len > MAX_BUFFER_SIZE) {
+            mp_raise_ValueError(MP_ERROR_TEXT("rxbuf too large"));
+        }
+    }
+
+    #if USART_BUFFER_TX
+    // Set the TX buffer size if configured.
+    size_t txbuf_len = DEFAULT_BUFFER_SIZE;
+    if (args[ARG_txbuf].u_int > 0) {
+        txbuf_len = args[ARG_txbuf].u_int;
+        if (txbuf_len < MIN_BUFFER_SIZE) {
+            txbuf_len = MIN_BUFFER_SIZE;
+        } else if (txbuf_len > MAX_BUFFER_SIZE) {
+            mp_raise_ValueError(MP_ERROR_TEXT("txbuf too large"));
+        }
+    }
+    #endif
+    // Initialise the UART peripheral if any arguments given, or it was not initialised previously.
+    if (n_args > 0 || kw_args->used > 0 || self->new) {
+        self->new = false;
+
+        // Check the rx/tx pin assignments
+        if (self->tx == 0xff || self->rx == 0xff || (self->tx / 4) != (self->rx / 4)) {
+            mp_raise_ValueError(MP_ERROR_TEXT("Non-matching or missing rx/tx"));
+        }
+        self->rx_pad_config = get_sercom_config(self->rx, self->id);
+        self->tx_pad_config = get_sercom_config(self->tx, self->id);
+
+        // Make sure timeout_char is at least as long as a whole character (13 bits to be safe).
+        uint32_t min_timeout_char = 13000 / self->baudrate + 1;
+        if (self->timeout_char < min_timeout_char) {
+            self->timeout_char = min_timeout_char;
+        }
+
+        // Allocate the RX/TX buffers.
+        ringbuf_alloc(&(self->read_buffer), rxbuf_len + 1);
+        MP_STATE_PORT(samd_uart_rx_buffer[self->id]) = self->read_buffer.buf;
+
+        #if USART_BUFFER_TX
+        ringbuf_alloc(&(self->write_buffer), txbuf_len + 1);
+        MP_STATE_PORT(samd_uart_tx_buffer[self->id]) = self->write_buffer.buf;
+        #endif
+
+        // Step 1: Configure the Pin mux.
+        mp_hal_set_pin_mux(self->rx, self->rx_pad_config.alt_fct);
+        mp_hal_set_pin_mux(self->tx, self->tx_pad_config.alt_fct);
+
+        // Next: Set up the clocks
+        enable_sercom_clock(self->id);
+
+        // Next: Configure the USART
+        Sercom *uart = sercom_instance[self->id];
+        // Reset (clear) the peripheral registers.
+        while (uart->USART.SYNCBUSY.bit.SWRST) {
+        }
+        uart->USART.CTRLA.bit.SWRST = 1; // Reset all Registers, disable peripheral
+        while (uart->USART.SYNCBUSY.bit.SWRST) {
+        }
+
+        uint8_t txpo = self->tx_pad_config.pad_nr;
+        #if defined(MCU_SAMD21)
+        if (self->tx_pad_config.pad_nr == 2) { // Map pad 2 to TXPO = 1
+            txpo = 1;
+        }
+        #endif
+
+        uart->USART.CTRLA.reg =
+            SERCOM_USART_CTRLA_DORD // Data order
+            | SERCOM_USART_CTRLA_FORM(self->parity != 0 ? 1 : 0)  // Enable parity or not
+            | SERCOM_USART_CTRLA_RXPO(self->rx_pad_config.pad_nr) // Set Pad#
+            | SERCOM_USART_CTRLA_TXPO(txpo) // Set Pad#
+            | SERCOM_USART_CTRLA_MODE(1) // USART with internal clock
+        ;
+        uart->USART.CTRLB.reg =
+            SERCOM_USART_CTRLB_RXEN   // Enable Rx & Tx
+            | SERCOM_USART_CTRLB_TXEN
+            | ((self->parity & 1) << SERCOM_USART_CTRLB_PMODE_Pos)
+            | (self->stop << SERCOM_USART_CTRLB_SBMODE_Pos)
+            | SERCOM_USART_CTRLB_CHSIZE((self->bits & 7) | (self->bits & 1))
+        ;
+        while (uart->USART.SYNCBUSY.bit.CTRLB) {
+        }
+
+        // USART is driven by the clock of GCLK Generator 2, freq by get_apb_freq()
+        // baud rate; 65536 * (1 - 16 * 115200/bus_freq)
+        uint32_t baud = 65536 - ((uint64_t)(65536 * 16) * self->baudrate + get_apb_freq() / 2) / get_apb_freq();
+        uart->USART.BAUD.bit.BAUD = baud; // Set Baud
+
+        // Enable RXC interrupt
+        uart->USART.INTENSET.bit.RXC = 1;
+        #if defined(MCU_SAMD21)
+        NVIC_EnableIRQ(SERCOM0_IRQn + self->id);
+        #elif defined(MCU_SAMD51)
+        NVIC_EnableIRQ(SERCOM0_0_IRQn + 4 * self->id + 2);
+        #endif
+        sercom_register_irq(self->id, SERCOM_IRQ_TYPE_UART);
+
+        sercom_enable(uart, 1);
+    }
+
+    return MP_OBJ_FROM_PTR(self);
+}
+
+STATIC mp_obj_t machine_uart_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+    mp_arg_check_num(n_args, n_kw, 1, MP_OBJ_FUN_ARGS_MAX, true);
+
+    // Get UART bus.
+    int uart_id = mp_obj_get_int(args[0]);
+    if (uart_id < 0 || uart_id > SERCOM_INST_NUM) {
+        mp_raise_msg_varg(&mp_type_ValueError, MP_ERROR_TEXT("UART(%d) doesn't exist"), uart_id);
+    }
+
+    // Create the UART object and fill it with defaults.
+    machine_uart_obj_t *self = mp_obj_malloc(machine_uart_obj_t, &machine_uart_type);
+    self->id = uart_id;
+    self->baudrate = DEFAULT_UART_BAUDRATE;
+    self->bits = 8;
+    self->stop = 0;
+    self->timeout = 1;
+    self->timeout_char = 1;
+    self->tx = 0xff;
+    self->rx = 0xff;
+    self->new = true;
+    uart_table[uart_id] = self;
+
+    mp_map_t kw_args;
+    mp_map_init_fixed_table(&kw_args, n_kw, args + n_args);
+    return machine_uart_init_helper(self, n_args - 1, args + 1, &kw_args);
+}
+
+// uart.init(baud, [kwargs])
+STATIC mp_obj_t machine_uart_init(size_t n_args, const mp_obj_t *args, mp_map_t *kw_args) {
+    return machine_uart_init_helper(args[0], n_args - 1, args + 1, kw_args);
+}
+MP_DEFINE_CONST_FUN_OBJ_KW(machine_uart_init_obj, 1, machine_uart_init);
+
+STATIC mp_obj_t machine_uart_deinit(mp_obj_t self_in) {
+    machine_uart_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    Sercom *uart = sercom_instance[self->id];
+    // clear table entry of uart
+    uart_table[self->id] = NULL;
+    // Disable interrupts
+    uart->USART.INTENCLR.reg = 0xff;
+    MP_STATE_PORT(samd_uart_rx_buffer[self->id]) = NULL;
+    #if USART_BUFFER_TX
+    MP_STATE_PORT(samd_uart_tx_buffer[self->id]) = NULL;
+    #endif
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(machine_uart_deinit_obj, machine_uart_deinit);
+
+STATIC mp_obj_t machine_uart_any(mp_obj_t self_in) {
+    machine_uart_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    // get all bytes from the fifo first
+    uart_drain_rx_fifo(self, sercom_instance[self->id]);
+    return MP_OBJ_NEW_SMALL_INT(ringbuf_avail(&self->read_buffer));
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(machine_uart_any_obj, machine_uart_any);
+
+STATIC mp_obj_t machine_uart_sendbreak(mp_obj_t self_in) {
+    machine_uart_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    uint32_t break_time_us = 13 * 1000000 / self->baudrate;
+
+    // Wait for the TX queue & register to clear
+    // Since the flags are not safe, just wait sufficiently long.
+    // Once tx buffering is implemented, wait as well for the buffer to clear.
+    mp_hal_delay_us(2 * break_time_us);
+    // Disable MUX
+    PORT->Group[self->tx / 32].PINCFG[self->tx % 32].bit.PMUXEN = 0;
+    // Set TX pin to low for break time
+    mp_hal_pin_low(self->tx);
+    mp_hal_delay_us(break_time_us);
+    mp_hal_pin_high(self->tx);
+    // Enable Mux again
+    mp_hal_set_pin_mux(self->tx, self->tx_pad_config.alt_fct);
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(machine_uart_sendbreak_obj, machine_uart_sendbreak);
+
+void uart_deinit_all(void) {
+    for (int i = 0; i < SERCOM_INST_NUM; i++) {
+        if (uart_table[i] != NULL) {
+            machine_uart_deinit((mp_obj_t)uart_table[i]);
+        }
+    }
+}
+
+STATIC const mp_rom_map_elem_t machine_uart_locals_dict_table[] = {
+    { MP_ROM_QSTR(MP_QSTR_init), MP_ROM_PTR(&machine_uart_init_obj) },
+    { MP_ROM_QSTR(MP_QSTR_deinit), MP_ROM_PTR(&machine_uart_deinit_obj) },
+
+    { MP_ROM_QSTR(MP_QSTR_any), MP_ROM_PTR(&machine_uart_any_obj) },
+    { MP_ROM_QSTR(MP_QSTR_sendbreak), MP_ROM_PTR(&machine_uart_sendbreak_obj) },
+
+    { MP_ROM_QSTR(MP_QSTR_read), MP_ROM_PTR(&mp_stream_read_obj) },
+    { MP_ROM_QSTR(MP_QSTR_readline), MP_ROM_PTR(&mp_stream_unbuffered_readline_obj) },
+    { MP_ROM_QSTR(MP_QSTR_readinto), MP_ROM_PTR(&mp_stream_readinto_obj) },
+    { MP_ROM_QSTR(MP_QSTR_write), MP_ROM_PTR(&mp_stream_write_obj) },
+};
+STATIC MP_DEFINE_CONST_DICT(machine_uart_locals_dict, machine_uart_locals_dict_table);
+
+STATIC mp_uint_t machine_uart_read(mp_obj_t self_in, void *buf_in, mp_uint_t size, int *errcode) {
+    machine_uart_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    uint64_t t = mp_hal_ticks_ms() + self->timeout;
+    uint64_t timeout_char = self->timeout_char;
+    uint8_t *dest = buf_in;
+    Sercom *uart = sercom_instance[self->id];
+
+    // t.b.d. Cater timeout for timer wrap after 50 days.
+    for (size_t i = 0; i < size; i++) {
+        // Wait for the first/next character
+        while (ringbuf_avail(&self->read_buffer) == 0) {
+            if (uart->USART.INTFLAG.bit.RXC != 0) {
+                // Force a few incoming bytes to the buffer
+                uart_drain_rx_fifo(self, uart);
+                break;
+            }
+            if (mp_hal_ticks_ms() > t) {  // timed out
+                if (i <= 0) {
+                    *errcode = MP_EAGAIN;
+                    return MP_STREAM_ERROR;
+                } else {
+                    return i;
+                }
+            }
+            MICROPY_EVENT_POLL_HOOK
+        }
+        *dest++ = ringbuf_get(&(self->read_buffer));
+        t = mp_hal_ticks_ms() + timeout_char;
+    }
+    return size;
+}
+
+STATIC mp_uint_t machine_uart_write(mp_obj_t self_in, const void *buf_in, mp_uint_t size, int *errcode) {
+    machine_uart_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    size_t remaining = size;
+    const uint8_t *src = buf_in;
+    Sercom *uart = sercom_instance[self->id];
+
+    while (remaining--) {
+        while (!(uart->USART.INTFLAG.bit.DRE)) {
+        }
+        uart->USART.DATA.bit.DATA = *src;
+        src += 1;
+    }
+
+    return size;
+}
+
+STATIC mp_uint_t machine_uart_ioctl(mp_obj_t self_in, mp_uint_t request, mp_uint_t arg, int *errcode) {
+    machine_uart_obj_t *self = self_in;
+    mp_uint_t ret;
+    Sercom *uart = sercom_instance[self->id];
+    if (request == MP_STREAM_POLL) {
+        uintptr_t flags = arg;
+        ret = 0;
+        if ((flags & MP_STREAM_POLL_RD) && (uart->USART.INTFLAG.bit.RXC != 0 || ringbuf_avail(&self->read_buffer) > 0)) {
+            ret |= MP_STREAM_POLL_RD;
+        }
+        if ((flags & MP_STREAM_POLL_WR) && (uart->USART.INTFLAG.bit.DRE != 0)) {
+            ret |= MP_STREAM_POLL_WR;
+        }
+    } else {
+        *errcode = MP_EINVAL;
+        ret = MP_STREAM_ERROR;
+    }
+    return ret;
+}
+
+STATIC const mp_stream_p_t uart_stream_p = {
+    .read = machine_uart_read,
+    .write = machine_uart_write,
+    .ioctl = machine_uart_ioctl,
+    .is_text = false,
+};
+
+MP_DEFINE_CONST_OBJ_TYPE(
+    machine_uart_type,
+    MP_QSTR_UART,
+    MP_TYPE_FLAG_ITER_IS_STREAM,
+    make_new, machine_uart_make_new,
+    print, machine_uart_print,
+    protocol, &uart_stream_p,
+    locals_dict, &machine_uart_locals_dict
+    );
+
+MP_REGISTER_ROOT_POINTER(void *samd_uart_rx_buffer[SERCOM_INST_NUM]);

ports/samd/main.c

@@ -36,6 +36,7 @@ extern uint8_t _sstack, _estack, _sheap, _eheap;
 extern void adc_deinit_all(void);
 extern void pin_irq_deinit_all(void);
 extern void pwm_deinit_all(void);
+extern void uart_deinit_all(void);
 
 void samd_main(void) {
     mp_stack_set_top(&_estack);
@@ -68,6 +69,7 @@ void samd_main(void) {
         adc_deinit_all();
         pin_irq_deinit_all();
         pwm_deinit_all();
+        uart_deinit_all();
         gc_sweep_all();
         mp_deinit();
     }

ports/samd/modmachine.c

@@ -155,6 +155,7 @@ STATIC const mp_rom_map_elem_t machine_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_PWM),                 MP_ROM_PTR(&machine_pwm_type) },
     { MP_ROM_QSTR(MP_QSTR_SoftI2C),             MP_ROM_PTR(&mp_machine_soft_i2c_type) },
     { MP_ROM_QSTR(MP_QSTR_SoftSPI),             MP_ROM_PTR(&mp_machine_soft_spi_type) },
+    { MP_ROM_QSTR(MP_QSTR_UART),                MP_ROM_PTR(&machine_uart_type) },
 
     { MP_ROM_QSTR(MP_QSTR_idle),                MP_ROM_PTR(&machine_idle_obj) },
     { MP_ROM_QSTR(MP_QSTR_disable_irq),         MP_ROM_PTR(&machine_disable_irq_obj) },

ports/samd/modmachine.h

@@ -32,5 +32,6 @@ extern const mp_obj_type_t machine_adc_type;
 extern const mp_obj_type_t machine_led_type;
 extern const mp_obj_type_t machine_pin_type;
 extern const mp_obj_type_t machine_pwm_type;
+extern const mp_obj_type_t machine_uart_type;
 
 #endif // MICROPY_INCLUDED_SAMD_MODMACHINE_H

ports/samd/mpconfigport.h

@@ -48,6 +48,7 @@
 #define MICROPY_HELPER_REPL                 (1)
 #define MICROPY_LONGINT_IMPL                (MICROPY_LONGINT_IMPL_MPZ)
 #define MICROPY_ENABLE_SOURCE_LINE          (1)
+#define MICROPY_STREAMS_NON_BLOCK           (1)
 #define MICROPY_ERROR_REPORTING             (MICROPY_ERROR_REPORTING_TERSE)
 #define MICROPY_CPYTHON_COMPAT              (0)
 #define MICROPY_CAN_OVERRIDE_BUILTINS       (1)

ports/samd/samd_isr.c

@@ -109,9 +109,9 @@ void PendSV_Handler(void) {
 
 
 static uint8_t sercom_irq_type[SERCOM_INST_NUM] = {};
+// Temporarily commented until the module is added
 void (*sercom_irq_handler_table[])(int num) = {
-    // Temporarily commented until the module is added
-    NULL, // common_uart_irq_handler,
+    common_uart_irq_handler,
     NULL, // common_spi_irq_handler,
     NULL  // common_i2c_irq_handler
 };