stmhal/uart.c - lite/micropython - Linaro Git Browser

 /*
  * This file is part of the Micro Python project, http://micropython.org/
  *
  * The MIT License (MIT)
  *
  * Copyright (c) 2013, 2014 Damien P. George
  *
  * 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 <stdio.h>
 #include <string.h>

 #include "stm32f4xx_hal.h"

 #include "mpconfig.h"
 #include "nlr.h"
 #include "misc.h"
 #include "qstr.h"
 #include "obj.h"
 #include "runtime.h"
 #include "bufhelper.h"
 #include "uart.h"

 /// \moduleref pyb
 /// \class UART - duplex serial communication bus
 ///
 /// UART implements the standard UART/USART duplex serial communications protocol.  At
 /// the physical level it consists of 2 lines: RX and TX.
 ///
 /// See usage model of I2C.  UART is very similar.  Main difference is
 /// parameters to init the UART bus:
 ///
 ///     from pyb import UART
 ///
 ///     uart = UART(1, 9600)                         # init with given baudrate
 ///     uart.init(9600, bits=8, stop=1, parity=None) # init with given parameters
 ///
 /// Bits can be 8 or 9, stop can be 1 or 2, parity can be None, 0 (even), 1 (odd).
 ///
 /// Extra method:
 ///
 ///     uart.any()               # returns True if any characters waiting

 struct _pyb_uart_obj_t {
     mp_obj_base_t base;
     pyb_uart_t uart_id;
     bool is_enabled;
     UART_HandleTypeDef uart;
 };

 pyb_uart_obj_t *pyb_uart_global_debug = NULL;

 // assumes Init parameters have been set up correctly
 bool uart_init2(pyb_uart_obj_t *uart_obj) {
     USART_TypeDef *UARTx = NULL;

     uint32_t GPIO_Pin = 0;
     uint8_t  GPIO_AF_UARTx = 0;
     GPIO_TypeDef* GPIO_Port = NULL;

     switch (uart_obj->uart_id) {
         // USART1 is on PA9/PA10 (CK on PA8), PB6/PB7
         case PYB_UART_1:
             UARTx = USART1;
             GPIO_AF_UARTx = GPIO_AF7_USART1;

 #if defined (PYBV4) || defined(PYBV10)
             GPIO_Port = GPIOB;
             GPIO_Pin = GPIO_PIN_6 | GPIO_PIN_7;
 #else
             GPIO_Port = GPIOA;
             GPIO_Pin = GPIO_PIN_9 | GPIO_PIN_10;
 #endif

             __USART1_CLK_ENABLE();
             break;

         // USART2 is on PA2/PA3 (CK on PA4), PD5/PD6 (CK on PD7)
         case PYB_UART_2:
             UARTx = USART2;
             GPIO_AF_UARTx = GPIO_AF7_USART2;

             GPIO_Port = GPIOA;
             GPIO_Pin = GPIO_PIN_2 | GPIO_PIN_3;

             __USART2_CLK_ENABLE();
             break;

         // USART3 is on PB10/PB11 (CK on PB12), PC10/PC11 (CK on PC12), PD8/PD9 (CK on PD10)
         case PYB_UART_3:
             UARTx = USART3;
             GPIO_AF_UARTx = GPIO_AF7_USART3;

 #if defined(PYBV3) || defined(PYBV4) | defined(PYBV10)
             GPIO_Port = GPIOB;
             GPIO_Pin = GPIO_PIN_10 | GPIO_PIN_11;
 #else
             GPIO_Port = GPIOD;
             GPIO_Pin = GPIO_PIN_8 | GPIO_PIN_9;
 #endif
             __USART3_CLK_ENABLE();
             break;

         // UART4 is on PA0/PA1, PC10/PC11
         case PYB_UART_4:
             UARTx = UART4;
             GPIO_AF_UARTx = GPIO_AF8_UART4;

             GPIO_Port = GPIOA;
             GPIO_Pin = GPIO_PIN_0 | GPIO_PIN_1;

             __UART4_CLK_ENABLE();
             break;

         // USART6 is on PC6/PC7 (CK on PC8)
         case PYB_UART_6:
             UARTx = USART6;
             GPIO_AF_UARTx = GPIO_AF8_USART6;

             GPIO_Port = GPIOC;
             GPIO_Pin = GPIO_PIN_6 | GPIO_PIN_7;

             __USART6_CLK_ENABLE();
             break;

         default:
             return false;
     }

     // init GPIO
     GPIO_InitTypeDef GPIO_InitStructure;
     GPIO_InitStructure.Pin = GPIO_Pin;
     GPIO_InitStructure.Speed = GPIO_SPEED_HIGH;
     GPIO_InitStructure.Mode = GPIO_MODE_AF_PP;
     GPIO_InitStructure.Pull = GPIO_PULLUP;
     GPIO_InitStructure.Alternate = GPIO_AF_UARTx;
     HAL_GPIO_Init(GPIO_Port, &GPIO_InitStructure);

     // init UARTx
     uart_obj->uart.Instance = UARTx;
     HAL_UART_Init(&uart_obj->uart);

     uart_obj->is_enabled = true;

     return true;
 }

 bool uart_init(pyb_uart_obj_t *uart_obj, uint32_t baudrate) {
     UART_HandleTypeDef *uh = &uart_obj->uart;
     memset(uh, 0, sizeof(*uh));
     uh->Init.BaudRate = baudrate;
     uh->Init.WordLength = UART_WORDLENGTH_8B;
     uh->Init.StopBits = UART_STOPBITS_1;
     uh->Init.Parity = UART_PARITY_NONE;
     uh->Init.Mode = UART_MODE_TX_RX;
     uh->Init.HwFlowCtl = UART_HWCONTROL_NONE;
     uh->Init.OverSampling = UART_OVERSAMPLING_16;
     return uart_init2(uart_obj);
 }

 void uart_deinit(pyb_uart_obj_t *uart_obj) {
     uart_obj->is_enabled = false;
     UART_HandleTypeDef *uart = &uart_obj->uart;
     HAL_UART_DeInit(uart);
     if (uart->Instance == USART1) {
         __USART1_FORCE_RESET();
         __USART1_RELEASE_RESET();
         __USART1_CLK_DISABLE();
     } else if (uart->Instance == USART2) {
         __USART2_FORCE_RESET();
         __USART2_RELEASE_RESET();
         __USART2_CLK_DISABLE();
     } else if (uart->Instance == USART3) {
         __USART3_FORCE_RESET();
         __USART3_RELEASE_RESET();
         __USART3_CLK_DISABLE();
     } else if (uart->Instance == UART4) {
         __UART4_FORCE_RESET();
         __UART4_RELEASE_RESET();
         __UART4_CLK_DISABLE();
     } else if (uart->Instance == USART6) {
         __USART6_FORCE_RESET();
         __USART6_RELEASE_RESET();
         __USART6_CLK_DISABLE();
     }
 }

 bool uart_rx_any(pyb_uart_obj_t *uart_obj) {
     return __HAL_UART_GET_FLAG(&uart_obj->uart, UART_FLAG_RXNE);
 }

 int uart_rx_char(pyb_uart_obj_t *uart_obj) {
     uint8_t ch;
     if (HAL_UART_Receive(&uart_obj->uart, &ch, 1, 0) != HAL_OK) {
         ch = 0;
     }
     return ch;
 }

 void uart_tx_char(pyb_uart_obj_t *uart_obj, int c) {
     uint8_t ch = c;
     HAL_UART_Transmit(&uart_obj->uart, &ch, 1, 100000);
 }

 void uart_tx_str(pyb_uart_obj_t *uart_obj, const char *str) {
     HAL_UART_Transmit(&uart_obj->uart, (uint8_t*)str, strlen(str), 100000);
 }

 void uart_tx_strn(pyb_uart_obj_t *uart_obj, const char *str, uint len) {
     HAL_UART_Transmit(&uart_obj->uart, (uint8_t*)str, len, 100000);
 }

 void uart_tx_strn_cooked(pyb_uart_obj_t *uart_obj, const char *str, uint len) {
     for (const char *top = str + len; str < top; str++) {
         if (*str == '\n') {
             uart_tx_char(uart_obj, '\r');
         }
         uart_tx_char(uart_obj, *str);
     }
 }

 /******************************************************************************/
 /* Micro Python bindings                                                      */

 STATIC void pyb_uart_print(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t self_in, mp_print_kind_t kind) {
     pyb_uart_obj_t *self = self_in;
     if (!self->is_enabled) {
         print(env, "UART(%lu)", self->uart_id);
     } else {
         print(env, "UART(%lu, baudrate=%u, bits=%u, stop=%u",
             self->uart_id, self->uart.Init.BaudRate,
             self->uart.Init.WordLength == UART_WORDLENGTH_8B ? 8 : 9,
             self->uart.Init.StopBits == UART_STOPBITS_1 ? 1 : 2);
         if (self->uart.Init.Parity == UART_PARITY_NONE) {
             print(env, ", parity=None)");
         } else {
             print(env, ", parity=%u)", self->uart.Init.Parity == UART_PARITY_EVEN ? 0 : 1);
         }
     }
 }

 /// \method init(baudrate, *, bits=8, stop=1, parity=None)
 ///
 /// Initialise the SPI bus with the given parameters:
 ///
 ///   - `baudrate` is the clock rate.
 ///   - `bits` is the number of bits per byte, 8 or 9.
 ///   - `stop` is the number of stop bits, 1 or 2.
 ///   - `parity` is the parity, `None`, 0 (even) or 1 (odd).
 STATIC const mp_arg_t pyb_uart_init_args[] = {
     { MP_QSTR_baudrate, MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = 9600} },
     { MP_QSTR_bits,     MP_ARG_KW_ONLY | MP_ARG_INT,  {.u_int = 8} },
     { MP_QSTR_stop,     MP_ARG_KW_ONLY | MP_ARG_INT,  {.u_int = 1} },
     { MP_QSTR_parity,   MP_ARG_KW_ONLY | MP_ARG_OBJ,  {.u_obj = mp_const_none} },
 };
 #define PYB_UART_INIT_NUM_ARGS MP_ARRAY_SIZE(pyb_uart_init_args)

 STATIC mp_obj_t pyb_uart_init_helper(pyb_uart_obj_t *self, uint n_args, const mp_obj_t *args, mp_map_t *kw_args) {
     // parse args
     mp_arg_val_t vals[PYB_UART_INIT_NUM_ARGS];
     mp_arg_parse_all(n_args, args, kw_args, PYB_UART_INIT_NUM_ARGS, pyb_uart_init_args, vals);

     // set the UART configuration values
     memset(&self->uart, 0, sizeof(self->uart));
     UART_InitTypeDef *init = &self->uart.Init;
     init->BaudRate = vals[0].u_int;
     init->WordLength = vals[1].u_int == 8 ? UART_WORDLENGTH_8B : UART_WORDLENGTH_9B;
     switch (vals[2].u_int) {
         case 1: init->StopBits = UART_STOPBITS_1; break;
         default: init->StopBits = UART_STOPBITS_2; break;
     }
     if (vals[3].u_obj == mp_const_none) {
         init->Parity = UART_PARITY_NONE;
     } else {
         mp_int_t parity = mp_obj_get_int(vals[3].u_obj);
         init->Parity = (parity & 1) ? UART_PARITY_ODD : UART_PARITY_EVEN;
     }
     init->Mode = UART_MODE_TX_RX;
     init->HwFlowCtl = UART_HWCONTROL_NONE;
     init->OverSampling = UART_OVERSAMPLING_16;

     // init UART (if it fails, it's because the port doesn't exist)
     if (!uart_init2(self)) {
         nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError, "UART port %d does not exist", self->uart_id));
     }

     return mp_const_none;
 }

 /// \classmethod \constructor(bus, ...)
 ///
 /// Construct a UART object on the given bus.  `bus` can be 1-6, or 'XA', 'XB', 'YA', or 'YB'.
 /// With no additional parameters, the UART object is created but not
 /// initialised (it has the settings from the last initialisation of
 /// the bus, if any).  If extra arguments are given, the bus is initialised.
 /// See `init` for parameters of initialisation.
 ///
 /// The physical pins of the UART busses are:
 ///
 ///   - `UART(4)` is on `XA`: `(TX, RX) = (X1, X2) = (PA0, PA1)`
 ///   - `UART(1)` is on `XB`: `(TX, RX) = (X9, X10) = (PB6, PB7)`
 ///   - `UART(6)` is on `YA`: `(TX, RX) = (Y1, Y2) = (PC6, PC7)`
 ///   - `UART(3)` is on `YB`: `(TX, RX) = (Y9, Y10) = (PB10, PB11)`
 ///   - `UART(2)` is on: `(TX, RX) = (X3, X4) = (PA2, PA3)`
 STATIC mp_obj_t pyb_uart_make_new(mp_obj_t type_in, uint n_args, uint n_kw, const mp_obj_t *args) {
     // check arguments
     mp_arg_check_num(n_args, n_kw, 1, MP_OBJ_FUN_ARGS_MAX, true);

     // create object
     pyb_uart_obj_t *o = m_new_obj(pyb_uart_obj_t);
     o->base.type = &pyb_uart_type;

     // work out port
     o->uart_id = 0;
     if (MP_OBJ_IS_STR(args[0])) {
         const char *port = mp_obj_str_get_str(args[0]);
         if (0) {
 #if defined(PYBV10)
         } else if (strcmp(port, "XA") == 0) {
             o->uart_id = PYB_UART_XA;
         } else if (strcmp(port, "XB") == 0) {
             o->uart_id = PYB_UART_XB;
         } else if (strcmp(port, "YA") == 0) {
             o->uart_id = PYB_UART_YA;
         } else if (strcmp(port, "YB") == 0) {
             o->uart_id = PYB_UART_YB;
 #endif
         } else {
             nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError, "UART port %s does not exist", port));
         }
     } else {
         o->uart_id = mp_obj_get_int(args[0]);
     }

     if (n_args > 1 || n_kw > 0) {
         // start the peripheral
         mp_map_t kw_args;
         mp_map_init_fixed_table(&kw_args, n_kw, args + n_args);
         pyb_uart_init_helper(o, n_args - 1, args + 1, &kw_args);
     }

     return o;
 }

 STATIC mp_obj_t pyb_uart_init(uint n_args, const mp_obj_t *args, mp_map_t *kw_args) {
     return pyb_uart_init_helper(args[0], n_args - 1, args + 1, kw_args);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_uart_init_obj, 1, pyb_uart_init);

 /// \method deinit()
 /// Turn off the UART bus.
 STATIC mp_obj_t pyb_uart_deinit(mp_obj_t self_in) {
     pyb_uart_obj_t *self = self_in;
     uart_deinit(self);
     return mp_const_none;
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(pyb_uart_deinit_obj, pyb_uart_deinit);

 /// \method any()
 /// Return `True` if any characters waiting, else `False`.
 STATIC mp_obj_t pyb_uart_any(mp_obj_t self_in) {
     pyb_uart_obj_t *self = self_in;
     if (uart_rx_any(self)) {
         return mp_const_true;
     } else {
         return mp_const_false;
     }
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(pyb_uart_any_obj, pyb_uart_any);

 /// \method send(send, *, timeout=5000)
 /// Send data on the bus:
 ///
 ///   - `send` is the data to send (an integer to send, or a buffer object).
 ///   - `timeout` is the timeout in milliseconds to wait for the send.
 ///
 /// Return value: `None`.
 STATIC const mp_arg_t pyb_uart_send_args[] = {
     { MP_QSTR_send,    MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
     { MP_QSTR_timeout, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 5000} },
 };
 #define PYB_UART_SEND_NUM_ARGS MP_ARRAY_SIZE(pyb_uart_send_args)

 STATIC mp_obj_t pyb_uart_send(uint n_args, const mp_obj_t *args, mp_map_t *kw_args) {
     // TODO assumes transmission size is 8-bits wide

     pyb_uart_obj_t *self = args[0];

     // parse args
     mp_arg_val_t vals[PYB_UART_SEND_NUM_ARGS];
     mp_arg_parse_all(n_args - 1, args + 1, kw_args, PYB_UART_SEND_NUM_ARGS, pyb_uart_send_args, vals);

     // get the buffer to send from
     mp_buffer_info_t bufinfo;
     uint8_t data[1];
     pyb_buf_get_for_send(vals[0].u_obj, &bufinfo, data);

     // send the data
     HAL_StatusTypeDef status = HAL_UART_Transmit(&self->uart, bufinfo.buf, bufinfo.len, vals[1].u_int);

     if (status != HAL_OK) {
         // TODO really need a HardwareError object, or something
         nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_Exception, "HAL_UART_Transmit failed with code %d", status));
     }

     return mp_const_none;
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_uart_send_obj, 1, pyb_uart_send);

 /// \method recv(recv, *, timeout=5000)
 ///
 /// Receive data on the bus:
 ///
 ///   - `recv` can be an integer, which is the number of bytes to receive,
 ///     or a mutable buffer, which will be filled with received bytes.
 ///   - `timeout` is the timeout in milliseconds to wait for the receive.
 ///
 /// Return value: if `recv` is an integer then a new buffer of the bytes received,
 /// otherwise the same buffer that was passed in to `recv`.
 STATIC const mp_arg_t pyb_uart_recv_args[] = {
     { MP_QSTR_recv,    MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
     { MP_QSTR_timeout, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 5000} },
 };
 #define PYB_UART_RECV_NUM_ARGS MP_ARRAY_SIZE(pyb_uart_recv_args)

 STATIC mp_obj_t pyb_uart_recv(uint n_args, const mp_obj_t *args, mp_map_t *kw_args) {
     // TODO assumes transmission size is 8-bits wide

     pyb_uart_obj_t *self = args[0];

     // parse args
     mp_arg_val_t vals[PYB_UART_RECV_NUM_ARGS];
     mp_arg_parse_all(n_args - 1, args + 1, kw_args, PYB_UART_RECV_NUM_ARGS, pyb_uart_recv_args, vals);

     // get the buffer to receive into
     mp_buffer_info_t bufinfo;
     mp_obj_t o_ret = pyb_buf_get_for_recv(vals[0].u_obj, &bufinfo);

     // receive the data
     HAL_StatusTypeDef status = HAL_UART_Receive(&self->uart, bufinfo.buf, bufinfo.len, vals[1].u_int);

     if (status != HAL_OK) {
         // TODO really need a HardwareError object, or something
         nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_Exception, "HAL_UART_Receive failed with code %d", status));
     }

     // return the received data
     if (o_ret == MP_OBJ_NULL) {
         return vals[0].u_obj;
     } else {
         return mp_obj_str_builder_end(o_ret);
     }
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_uart_recv_obj, 1, pyb_uart_recv);

 STATIC const mp_map_elem_t pyb_uart_locals_dict_table[] = {
     // instance methods
     { MP_OBJ_NEW_QSTR(MP_QSTR_init), (mp_obj_t)&pyb_uart_init_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_deinit), (mp_obj_t)&pyb_uart_deinit_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_any), (mp_obj_t)&pyb_uart_any_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_send), (mp_obj_t)&pyb_uart_send_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_recv), (mp_obj_t)&pyb_uart_recv_obj },
 };

 STATIC MP_DEFINE_CONST_DICT(pyb_uart_locals_dict, pyb_uart_locals_dict_table);

 const mp_obj_type_t pyb_uart_type = {
     { &mp_type_type },
     .name = MP_QSTR_UART,
     .print = pyb_uart_print,
     .make_new = pyb_uart_make_new,
     .locals_dict = (mp_obj_t)&pyb_uart_locals_dict,
 };
	/*
	* This file is part of the Micro Python project, http://micropython.org/
	*
	* The MIT License (MIT)
	*
	* Copyright (c) 2013, 2014 Damien P. George
	*
	* 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 <stdio.h>
	#include <string.h>

	#include "stm32f4xx_hal.h"

	#include "mpconfig.h"
	#include "nlr.h"
	#include "misc.h"
	#include "qstr.h"
	#include "obj.h"
	#include "runtime.h"
	#include "bufhelper.h"
	#include "uart.h"

	/// \moduleref pyb
	/// \class UART - duplex serial communication bus
	///
	/// UART implements the standard UART/USART duplex serial communications protocol. At
	/// the physical level it consists of 2 lines: RX and TX.
	///
	/// See usage model of I2C. UART is very similar. Main difference is
	/// parameters to init the UART bus:
	///
	/// from pyb import UART
	///
	/// uart = UART(1, 9600) # init with given baudrate
	/// uart.init(9600, bits=8, stop=1, parity=None) # init with given parameters
	///
	/// Bits can be 8 or 9, stop can be 1 or 2, parity can be None, 0 (even), 1 (odd).
	///
	/// Extra method:
	///
	/// uart.any() # returns True if any characters waiting

	struct _pyb_uart_obj_t {
	mp_obj_base_t base;
	pyb_uart_t uart_id;
	bool is_enabled;
	UART_HandleTypeDef uart;
	};

	pyb_uart_obj_t *pyb_uart_global_debug = NULL;

	// assumes Init parameters have been set up correctly
	bool uart_init2(pyb_uart_obj_t *uart_obj) {
	USART_TypeDef *UARTx = NULL;

	uint32_t GPIO_Pin = 0;
	uint8_t GPIO_AF_UARTx = 0;
	GPIO_TypeDef* GPIO_Port = NULL;

	switch (uart_obj->uart_id) {
	// USART1 is on PA9/PA10 (CK on PA8), PB6/PB7
	case PYB_UART_1:
	UARTx = USART1;
	GPIO_AF_UARTx = GPIO_AF7_USART1;

	#if defined (PYBV4) \|\| defined(PYBV10)
	GPIO_Port = GPIOB;
	GPIO_Pin = GPIO_PIN_6 \| GPIO_PIN_7;
	#else
	GPIO_Port = GPIOA;
	GPIO_Pin = GPIO_PIN_9 \| GPIO_PIN_10;
	#endif

	__USART1_CLK_ENABLE();
	break;

	// USART2 is on PA2/PA3 (CK on PA4), PD5/PD6 (CK on PD7)
	case PYB_UART_2:
	UARTx = USART2;
	GPIO_AF_UARTx = GPIO_AF7_USART2;

	GPIO_Port = GPIOA;
	GPIO_Pin = GPIO_PIN_2 \| GPIO_PIN_3;

	__USART2_CLK_ENABLE();
	break;

	// USART3 is on PB10/PB11 (CK on PB12), PC10/PC11 (CK on PC12), PD8/PD9 (CK on PD10)
	case PYB_UART_3:
	UARTx = USART3;
	GPIO_AF_UARTx = GPIO_AF7_USART3;

	#if defined(PYBV3) \|\| defined(PYBV4) \| defined(PYBV10)
	GPIO_Port = GPIOB;
	GPIO_Pin = GPIO_PIN_10 \| GPIO_PIN_11;
	#else
	GPIO_Port = GPIOD;
	GPIO_Pin = GPIO_PIN_8 \| GPIO_PIN_9;
	#endif
	__USART3_CLK_ENABLE();
	break;

	// UART4 is on PA0/PA1, PC10/PC11
	case PYB_UART_4:
	UARTx = UART4;
	GPIO_AF_UARTx = GPIO_AF8_UART4;

	GPIO_Port = GPIOA;
	GPIO_Pin = GPIO_PIN_0 \| GPIO_PIN_1;

	__UART4_CLK_ENABLE();
	break;

	// USART6 is on PC6/PC7 (CK on PC8)
	case PYB_UART_6:
	UARTx = USART6;
	GPIO_AF_UARTx = GPIO_AF8_USART6;

	GPIO_Port = GPIOC;
	GPIO_Pin = GPIO_PIN_6 \| GPIO_PIN_7;

	__USART6_CLK_ENABLE();
	break;

	default:
	return false;
	}

	// init GPIO
	GPIO_InitTypeDef GPIO_InitStructure;
	GPIO_InitStructure.Pin = GPIO_Pin;
	GPIO_InitStructure.Speed = GPIO_SPEED_HIGH;
	GPIO_InitStructure.Mode = GPIO_MODE_AF_PP;
	GPIO_InitStructure.Pull = GPIO_PULLUP;
	GPIO_InitStructure.Alternate = GPIO_AF_UARTx;
	HAL_GPIO_Init(GPIO_Port, &GPIO_InitStructure);

	// init UARTx
	uart_obj->uart.Instance = UARTx;
	HAL_UART_Init(&uart_obj->uart);

	uart_obj->is_enabled = true;

	return true;
	}

	bool uart_init(pyb_uart_obj_t *uart_obj, uint32_t baudrate) {
	UART_HandleTypeDef *uh = &uart_obj->uart;
	memset(uh, 0, sizeof(*uh));
	uh->Init.BaudRate = baudrate;
	uh->Init.WordLength = UART_WORDLENGTH_8B;
	uh->Init.StopBits = UART_STOPBITS_1;
	uh->Init.Parity = UART_PARITY_NONE;
	uh->Init.Mode = UART_MODE_TX_RX;
	uh->Init.HwFlowCtl = UART_HWCONTROL_NONE;
	uh->Init.OverSampling = UART_OVERSAMPLING_16;
	return uart_init2(uart_obj);
	}

	void uart_deinit(pyb_uart_obj_t *uart_obj) {
	uart_obj->is_enabled = false;
	UART_HandleTypeDef *uart = &uart_obj->uart;
	HAL_UART_DeInit(uart);
	if (uart->Instance == USART1) {
	__USART1_FORCE_RESET();
	__USART1_RELEASE_RESET();
	__USART1_CLK_DISABLE();
	} else if (uart->Instance == USART2) {
	__USART2_FORCE_RESET();
	__USART2_RELEASE_RESET();
	__USART2_CLK_DISABLE();
	} else if (uart->Instance == USART3) {
	__USART3_FORCE_RESET();
	__USART3_RELEASE_RESET();
	__USART3_CLK_DISABLE();
	} else if (uart->Instance == UART4) {
	__UART4_FORCE_RESET();
	__UART4_RELEASE_RESET();
	__UART4_CLK_DISABLE();
	} else if (uart->Instance == USART6) {
	__USART6_FORCE_RESET();
	__USART6_RELEASE_RESET();
	__USART6_CLK_DISABLE();
	}
	}

	bool uart_rx_any(pyb_uart_obj_t *uart_obj) {
	return __HAL_UART_GET_FLAG(&uart_obj->uart, UART_FLAG_RXNE);
	}

	int uart_rx_char(pyb_uart_obj_t *uart_obj) {
	uint8_t ch;
	if (HAL_UART_Receive(&uart_obj->uart, &ch, 1, 0) != HAL_OK) {
	ch = 0;
	}
	return ch;
	}

	void uart_tx_char(pyb_uart_obj_t *uart_obj, int c) {
	uint8_t ch = c;
	HAL_UART_Transmit(&uart_obj->uart, &ch, 1, 100000);
	}

	void uart_tx_str(pyb_uart_obj_t uart_obj, const char str) {
	HAL_UART_Transmit(&uart_obj->uart, (uint8_t*)str, strlen(str), 100000);
	}

	void uart_tx_strn(pyb_uart_obj_t uart_obj, const char str, uint len) {
	HAL_UART_Transmit(&uart_obj->uart, (uint8_t*)str, len, 100000);
	}

	void uart_tx_strn_cooked(pyb_uart_obj_t uart_obj, const char str, uint len) {
	for (const char *top = str + len; str < top; str++) {
	if (*str == '\n') {
	uart_tx_char(uart_obj, '\r');
	}
	uart_tx_char(uart_obj, *str);
	}
	}

	/******************************************************************************/
	/* Micro Python bindings */

	STATIC void pyb_uart_print(void (print)(void env, const char fmt, ...), void env, mp_obj_t self_in, mp_print_kind_t kind) {
	pyb_uart_obj_t *self = self_in;
	if (!self->is_enabled) {
	print(env, "UART(%lu)", self->uart_id);
	} else {
	print(env, "UART(%lu, baudrate=%u, bits=%u, stop=%u",
	self->uart_id, self->uart.Init.BaudRate,
	self->uart.Init.WordLength == UART_WORDLENGTH_8B ? 8 : 9,
	self->uart.Init.StopBits == UART_STOPBITS_1 ? 1 : 2);
	if (self->uart.Init.Parity == UART_PARITY_NONE) {
	print(env, ", parity=None)");
	} else {
	print(env, ", parity=%u)", self->uart.Init.Parity == UART_PARITY_EVEN ? 0 : 1);
	}
	}
	}

	/// \method init(baudrate, *, bits=8, stop=1, parity=None)
	///
	/// Initialise the SPI bus with the given parameters:
	///
	/// - `baudrate` is the clock rate.
	/// - `bits` is the number of bits per byte, 8 or 9.
	/// - `stop` is the number of stop bits, 1 or 2.
	/// - `parity` is the parity, `None`, 0 (even) or 1 (odd).
	STATIC const mp_arg_t pyb_uart_init_args[] = {
	{ MP_QSTR_baudrate, MP_ARG_REQUIRED \| MP_ARG_INT, {.u_int = 9600} },
	{ MP_QSTR_bits, MP_ARG_KW_ONLY \| MP_ARG_INT, {.u_int = 8} },
	{ MP_QSTR_stop, MP_ARG_KW_ONLY \| MP_ARG_INT, {.u_int = 1} },
	{ MP_QSTR_parity, MP_ARG_KW_ONLY \| MP_ARG_OBJ, {.u_obj = mp_const_none} },
	};
	#define PYB_UART_INIT_NUM_ARGS MP_ARRAY_SIZE(pyb_uart_init_args)

	STATIC mp_obj_t pyb_uart_init_helper(pyb_uart_obj_t self, uint n_args, const mp_obj_t args, mp_map_t *kw_args) {
	// parse args
	mp_arg_val_t vals[PYB_UART_INIT_NUM_ARGS];
	mp_arg_parse_all(n_args, args, kw_args, PYB_UART_INIT_NUM_ARGS, pyb_uart_init_args, vals);

	// set the UART configuration values
	memset(&self->uart, 0, sizeof(self->uart));
	UART_InitTypeDef *init = &self->uart.Init;
	init->BaudRate = vals[0].u_int;
	init->WordLength = vals[1].u_int == 8 ? UART_WORDLENGTH_8B : UART_WORDLENGTH_9B;
	switch (vals[2].u_int) {
	case 1: init->StopBits = UART_STOPBITS_1; break;
	default: init->StopBits = UART_STOPBITS_2; break;
	}
	if (vals[3].u_obj == mp_const_none) {
	init->Parity = UART_PARITY_NONE;
	} else {
	mp_int_t parity = mp_obj_get_int(vals[3].u_obj);
	init->Parity = (parity & 1) ? UART_PARITY_ODD : UART_PARITY_EVEN;
	}
	init->Mode = UART_MODE_TX_RX;
	init->HwFlowCtl = UART_HWCONTROL_NONE;
	init->OverSampling = UART_OVERSAMPLING_16;

	// init UART (if it fails, it's because the port doesn't exist)
	if (!uart_init2(self)) {
	nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError, "UART port %d does not exist", self->uart_id));
	}

	return mp_const_none;
	}

	/// \classmethod \constructor(bus, ...)
	///
	/// Construct a UART object on the given bus. `bus` can be 1-6, or 'XA', 'XB', 'YA', or 'YB'.
	/// With no additional parameters, the UART object is created but not
	/// initialised (it has the settings from the last initialisation of
	/// the bus, if any). If extra arguments are given, the bus is initialised.
	/// See `init` for parameters of initialisation.
	///
	/// The physical pins of the UART busses are:
	///
	/// - `UART(4)` is on `XA`: `(TX, RX) = (X1, X2) = (PA0, PA1)`
	/// - `UART(1)` is on `XB`: `(TX, RX) = (X9, X10) = (PB6, PB7)`
	/// - `UART(6)` is on `YA`: `(TX, RX) = (Y1, Y2) = (PC6, PC7)`
	/// - `UART(3)` is on `YB`: `(TX, RX) = (Y9, Y10) = (PB10, PB11)`
	/// - `UART(2)` is on: `(TX, RX) = (X3, X4) = (PA2, PA3)`
	STATIC mp_obj_t pyb_uart_make_new(mp_obj_t type_in, uint n_args, uint n_kw, const mp_obj_t *args) {
	// check arguments
	mp_arg_check_num(n_args, n_kw, 1, MP_OBJ_FUN_ARGS_MAX, true);

	// create object
	pyb_uart_obj_t *o = m_new_obj(pyb_uart_obj_t);
	o->base.type = &pyb_uart_type;

	// work out port
	o->uart_id = 0;
	if (MP_OBJ_IS_STR(args[0])) {
	const char *port = mp_obj_str_get_str(args[0]);
	if (0) {
	#if defined(PYBV10)
	} else if (strcmp(port, "XA") == 0) {
	o->uart_id = PYB_UART_XA;
	} else if (strcmp(port, "XB") == 0) {
	o->uart_id = PYB_UART_XB;
	} else if (strcmp(port, "YA") == 0) {
	o->uart_id = PYB_UART_YA;
	} else if (strcmp(port, "YB") == 0) {
	o->uart_id = PYB_UART_YB;
	#endif
	} else {
	nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError, "UART port %s does not exist", port));
	}
	} else {
	o->uart_id = mp_obj_get_int(args[0]);
	}

	if (n_args > 1 \|\| n_kw > 0) {
	// start the peripheral
	mp_map_t kw_args;
	mp_map_init_fixed_table(&kw_args, n_kw, args + n_args);
	pyb_uart_init_helper(o, n_args - 1, args + 1, &kw_args);
	}

	return o;
	}

	STATIC mp_obj_t pyb_uart_init(uint n_args, const mp_obj_t args, mp_map_t kw_args) {
	return pyb_uart_init_helper(args[0], n_args - 1, args + 1, kw_args);
	}
	STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_uart_init_obj, 1, pyb_uart_init);

	/// \method deinit()
	/// Turn off the UART bus.
	STATIC mp_obj_t pyb_uart_deinit(mp_obj_t self_in) {
	pyb_uart_obj_t *self = self_in;
	uart_deinit(self);
	return mp_const_none;
	}
	STATIC MP_DEFINE_CONST_FUN_OBJ_1(pyb_uart_deinit_obj, pyb_uart_deinit);

	/// \method any()
	/// Return `True` if any characters waiting, else `False`.
	STATIC mp_obj_t pyb_uart_any(mp_obj_t self_in) {
	pyb_uart_obj_t *self = self_in;
	if (uart_rx_any(self)) {
	return mp_const_true;
	} else {
	return mp_const_false;
	}
	}
	STATIC MP_DEFINE_CONST_FUN_OBJ_1(pyb_uart_any_obj, pyb_uart_any);

	/// \method send(send, *, timeout=5000)
	/// Send data on the bus:
	///
	/// - `send` is the data to send (an integer to send, or a buffer object).
	/// - `timeout` is the timeout in milliseconds to wait for the send.
	///
	/// Return value: `None`.
	STATIC const mp_arg_t pyb_uart_send_args[] = {
	{ MP_QSTR_send, MP_ARG_REQUIRED \| MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
	{ MP_QSTR_timeout, MP_ARG_KW_ONLY \| MP_ARG_INT, {.u_int = 5000} },
	};
	#define PYB_UART_SEND_NUM_ARGS MP_ARRAY_SIZE(pyb_uart_send_args)

	STATIC mp_obj_t pyb_uart_send(uint n_args, const mp_obj_t args, mp_map_t kw_args) {
	// TODO assumes transmission size is 8-bits wide

	pyb_uart_obj_t *self = args[0];

	// parse args
	mp_arg_val_t vals[PYB_UART_SEND_NUM_ARGS];
	mp_arg_parse_all(n_args - 1, args + 1, kw_args, PYB_UART_SEND_NUM_ARGS, pyb_uart_send_args, vals);

	// get the buffer to send from
	mp_buffer_info_t bufinfo;
	uint8_t data[1];
	pyb_buf_get_for_send(vals[0].u_obj, &bufinfo, data);

	// send the data
	HAL_StatusTypeDef status = HAL_UART_Transmit(&self->uart, bufinfo.buf, bufinfo.len, vals[1].u_int);

	if (status != HAL_OK) {
	// TODO really need a HardwareError object, or something
	nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_Exception, "HAL_UART_Transmit failed with code %d", status));
	}

	return mp_const_none;
	}
	STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_uart_send_obj, 1, pyb_uart_send);

	/// \method recv(recv, *, timeout=5000)
	///
	/// Receive data on the bus:
	///
	/// - `recv` can be an integer, which is the number of bytes to receive,
	/// or a mutable buffer, which will be filled with received bytes.
	/// - `timeout` is the timeout in milliseconds to wait for the receive.
	///
	/// Return value: if `recv` is an integer then a new buffer of the bytes received,
	/// otherwise the same buffer that was passed in to `recv`.
	STATIC const mp_arg_t pyb_uart_recv_args[] = {
	{ MP_QSTR_recv, MP_ARG_REQUIRED \| MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
	{ MP_QSTR_timeout, MP_ARG_KW_ONLY \| MP_ARG_INT, {.u_int = 5000} },
	};
	#define PYB_UART_RECV_NUM_ARGS MP_ARRAY_SIZE(pyb_uart_recv_args)

	STATIC mp_obj_t pyb_uart_recv(uint n_args, const mp_obj_t args, mp_map_t kw_args) {
	// TODO assumes transmission size is 8-bits wide

	pyb_uart_obj_t *self = args[0];

	// parse args
	mp_arg_val_t vals[PYB_UART_RECV_NUM_ARGS];
	mp_arg_parse_all(n_args - 1, args + 1, kw_args, PYB_UART_RECV_NUM_ARGS, pyb_uart_recv_args, vals);

	// get the buffer to receive into
	mp_buffer_info_t bufinfo;
	mp_obj_t o_ret = pyb_buf_get_for_recv(vals[0].u_obj, &bufinfo);

	// receive the data
	HAL_StatusTypeDef status = HAL_UART_Receive(&self->uart, bufinfo.buf, bufinfo.len, vals[1].u_int);

	if (status != HAL_OK) {
	// TODO really need a HardwareError object, or something
	nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_Exception, "HAL_UART_Receive failed with code %d", status));
	}

	// return the received data
	if (o_ret == MP_OBJ_NULL) {
	return vals[0].u_obj;
	} else {
	return mp_obj_str_builder_end(o_ret);
	}
	}
	STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_uart_recv_obj, 1, pyb_uart_recv);

	STATIC const mp_map_elem_t pyb_uart_locals_dict_table[] = {
	// instance methods
	{ MP_OBJ_NEW_QSTR(MP_QSTR_init), (mp_obj_t)&pyb_uart_init_obj },
	{ MP_OBJ_NEW_QSTR(MP_QSTR_deinit), (mp_obj_t)&pyb_uart_deinit_obj },
	{ MP_OBJ_NEW_QSTR(MP_QSTR_any), (mp_obj_t)&pyb_uart_any_obj },
	{ MP_OBJ_NEW_QSTR(MP_QSTR_send), (mp_obj_t)&pyb_uart_send_obj },
	{ MP_OBJ_NEW_QSTR(MP_QSTR_recv), (mp_obj_t)&pyb_uart_recv_obj },
	};

	STATIC MP_DEFINE_CONST_DICT(pyb_uart_locals_dict, pyb_uart_locals_dict_table);

	const mp_obj_type_t pyb_uart_type = {
	{ &mp_type_type },
	.name = MP_QSTR_UART,
	.print = pyb_uart_print,
	.make_new = pyb_uart_make_new,
	.locals_dict = (mp_obj_t)&pyb_uart_locals_dict,
	};