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28 results

internal.h

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    uart.c 33.65 KiB
    /*
     * 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 <stdarg.h>
    
    #include "py/nlr.h"
    #include "py/runtime.h"
    #include "py/stream.h"
    #include "py/mperrno.h"
    #include "py/mphal.h"
    #include "uart.h"
    #include "pybioctl.h"
    #include "irq.h"
    
    //TODO: Add UART7/8 support for MCU_SERIES_F7
    
    /// \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.  The unit of communication
    /// is a character (not to be confused with a string character) which can be 8 or 9
    /// bits wide.
    ///
    /// UART objects can be created and initialised using:
    ///
    ///     from pyb import UART
    ///
    ///     uart = UART(1, 9600)                         # init with given baudrate
    ///     uart.init(9600, bits=8, parity=None, stop=1) # init with given parameters
    ///
    /// Bits can be 8 or 9.  Parity can be None, 0 (even) or 1 (odd).  Stop can be 1 or 2.
    ///
    /// A UART object acts like a stream object and reading and writing is done
    /// using the standard stream methods:
    ///
    ///     uart.read(10)       # read 10 characters, returns a bytes object
    ///     uart.readall()      # read all available characters
    ///     uart.readline()     # read a line
    ///     uart.readinto(buf)  # read and store into the given buffer
    ///     uart.write('abc')   # write the 3 characters
    ///
    /// Individual characters can be read/written using:
    ///
    ///     uart.readchar()     # read 1 character and returns it as an integer
    ///     uart.writechar(42)  # write 1 character
    ///
    /// To check if there is anything to be read, use:
    ///
    ///     uart.any()               # returns True if any characters waiting
    
    #define CHAR_WIDTH_8BIT (0)
    #define CHAR_WIDTH_9BIT (1)
    
    struct _pyb_uart_obj_t {
        mp_obj_base_t base;
        UART_HandleTypeDef uart;            // this is 17 words big
        IRQn_Type irqn;
        pyb_uart_t uart_id : 8;
        bool is_enabled : 1;
        byte char_width;                    // 0 for 7,8 bit chars, 1 for 9 bit chars
        uint16_t char_mask;                 // 0x7f for 7 bit, 0xff for 8 bit, 0x1ff for 9 bit
        uint16_t timeout;                   // timeout waiting for first char
        uint16_t timeout_char;              // timeout waiting between chars
        uint16_t read_buf_len;              // len in chars; buf can hold len-1 chars
        volatile uint16_t read_buf_head;    // indexes first empty slot
        uint16_t read_buf_tail;             // indexes first full slot (not full if equals head)
        byte *read_buf;                     // byte or uint16_t, depending on char size
    };
    
    STATIC mp_obj_t pyb_uart_deinit(mp_obj_t self_in);
    
    void uart_init0(void) {
        for (int i = 0; i < MP_ARRAY_SIZE(MP_STATE_PORT(pyb_uart_obj_all)); i++) {
            MP_STATE_PORT(pyb_uart_obj_all)[i] = NULL;
        }
    }
    
    // unregister all interrupt sources
    void uart_deinit(void) {
        for (int i = 0; i < MP_ARRAY_SIZE(MP_STATE_PORT(pyb_uart_obj_all)); i++) {
            pyb_uart_obj_t *uart_obj = MP_STATE_PORT(pyb_uart_obj_all)[i];
            if (uart_obj != NULL) {
                pyb_uart_deinit(uart_obj);
            }
        }
    }
    
    // assumes Init parameters have been set up correctly
    STATIC bool uart_init2(pyb_uart_obj_t *uart_obj) {
        USART_TypeDef *UARTx;
        IRQn_Type irqn;
        uint32_t GPIO_Pin, GPIO_Pin2 = 0;
        uint8_t GPIO_AF_UARTx = 0;
        GPIO_TypeDef* GPIO_Port = NULL;
        GPIO_TypeDef* GPIO_Port2 = NULL;
    
        switch (uart_obj->uart_id) {
            #if defined(MICROPY_HW_UART1_PORT) && defined(MICROPY_HW_UART1_PINS)
            // USART1 is on PA9/PA10 (CK on PA8), PB6/PB7
            case PYB_UART_1:
                UARTx = USART1;
                irqn = USART1_IRQn;
                GPIO_AF_UARTx = GPIO_AF7_USART1;
                GPIO_Port = MICROPY_HW_UART1_PORT;
                GPIO_Pin = MICROPY_HW_UART1_PINS;
                __USART1_CLK_ENABLE();
                break;
            #endif
    
            #if defined(MICROPY_HW_UART1_TX_PORT) && \
                defined(MICROPY_HW_UART1_TX_PIN) && \
                defined(MICROPY_HW_UART1_RX_PORT) && \
                defined(MICROPY_HW_UART1_RX_PIN)
            case PYB_UART_1:
                UARTx = USART1;
                irqn = USART1_IRQn;
                GPIO_AF_UARTx = GPIO_AF7_USART1;
                GPIO_Port  = MICROPY_HW_UART1_TX_PORT;
                GPIO_Pin   = MICROPY_HW_UART1_TX_PIN;
                GPIO_Port2 = MICROPY_HW_UART1_RX_PORT;
                GPIO_Pin2  = MICROPY_HW_UART1_RX_PIN;
                __USART1_CLK_ENABLE();
                break;
            #endif
    
            #if defined(MICROPY_HW_UART2_PORT) && defined(MICROPY_HW_UART2_PINS)
            case PYB_UART_2:
                UARTx = USART2;
                irqn = USART2_IRQn;
                GPIO_AF_UARTx = GPIO_AF7_USART2;
                GPIO_Port = MICROPY_HW_UART2_PORT;
                GPIO_Pin = MICROPY_HW_UART2_PINS;
                #if defined(MICROPY_HW_UART2_RTS)
                if (uart_obj->uart.Init.HwFlowCtl & UART_HWCONTROL_RTS) {
                    GPIO_Pin |= MICROPY_HW_UART2_RTS;
                }
                #endif
                #if defined(MICROPY_HW_UART2_CTS)
                if (uart_obj->uart.Init.HwFlowCtl & UART_HWCONTROL_CTS) {
                    GPIO_Pin |= MICROPY_HW_UART2_CTS;
                }
                #endif
                __USART2_CLK_ENABLE();
                break;
            #endif
    
            #if defined(USART3) && defined(MICROPY_HW_UART3_PORT) && defined(MICROPY_HW_UART3_PINS)
            // USART3 is on PB10/PB11 (CK,CTS,RTS on PB12,PB13,PB14), PC10/PC11 (CK on PC12), PD8/PD9 (CK on PD10)
            case PYB_UART_3:
                UARTx = USART3;
                irqn = USART3_IRQn;
                GPIO_AF_UARTx = GPIO_AF7_USART3;
                GPIO_Port = MICROPY_HW_UART3_PORT;
                GPIO_Pin = MICROPY_HW_UART3_PINS;
                #if defined(MICROPY_HW_UART3_RTS)
                if (uart_obj->uart.Init.HwFlowCtl & UART_HWCONTROL_RTS) {
                    GPIO_Pin |= MICROPY_HW_UART3_RTS;
                }
                #endif
                #if defined(MICROPY_HW_UART3_CTS)
                if (uart_obj->uart.Init.HwFlowCtl & UART_HWCONTROL_CTS) {
                    GPIO_Pin |= MICROPY_HW_UART3_CTS;
                }
                #endif
                __USART3_CLK_ENABLE();
                break;
            #endif
    
            #if defined(UART4) && defined(MICROPY_HW_UART4_PORT) && defined(MICROPY_HW_UART4_PINS)
            // UART4 is on PA0/PA1, PC10/PC11
            case PYB_UART_4:
                UARTx = UART4;
                irqn = UART4_IRQn;
                GPIO_AF_UARTx = GPIO_AF8_UART4;
                GPIO_Port = MICROPY_HW_UART4_PORT;
                GPIO_Pin = MICROPY_HW_UART4_PINS;
                __UART4_CLK_ENABLE();
                break;
            #endif
    
            #if defined(UART5) && \
                defined(MICROPY_HW_UART5_TX_PORT) && \
                defined(MICROPY_HW_UART5_TX_PIN) && \
                defined(MICROPY_HW_UART5_RX_PORT) && \
                defined(MICROPY_HW_UART5_RX_PIN)
            case PYB_UART_5:
                UARTx = UART5;
                irqn = UART5_IRQn;
                GPIO_AF_UARTx = GPIO_AF8_UART5;
                GPIO_Port = MICROPY_HW_UART5_TX_PORT;
                GPIO_Port2 = MICROPY_HW_UART5_RX_PORT;
                GPIO_Pin = MICROPY_HW_UART5_TX_PIN;
                GPIO_Pin2 = MICROPY_HW_UART5_RX_PIN;
                __UART5_CLK_ENABLE();
                break;
            #endif
    
            #if defined(MICROPY_HW_UART6_PORT) && defined(MICROPY_HW_UART6_PINS)
            // USART6 is on PC6/PC7 (CK on PC8)
            case PYB_UART_6:
                UARTx = USART6;
                irqn = USART6_IRQn;
                GPIO_AF_UARTx = GPIO_AF8_USART6;
                GPIO_Port = MICROPY_HW_UART6_PORT;
                GPIO_Pin = MICROPY_HW_UART6_PINS;
                __USART6_CLK_ENABLE();
                break;
            #endif
    
            default:
                // UART does not exist or is not configured for this board
                return false;
        }
    
        uart_obj->irqn = irqn;
        uart_obj->uart.Instance = UARTx;
    
        // init GPIO
        mp_hal_gpio_clock_enable(GPIO_Port);
        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 GPIO for second pin if needed
        if (GPIO_Port2 != NULL) {
            mp_hal_gpio_clock_enable(GPIO_Port2);
            GPIO_InitStructure.Pin = GPIO_Pin2;
            HAL_GPIO_Init(GPIO_Port2, &GPIO_InitStructure);
        }
    
        // init UARTx
        HAL_UART_Init(&uart_obj->uart);
    
        uart_obj->is_enabled = true;
    
        return true;
    }
    
    /* obsolete and unused
    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);
    }
    */
    
    mp_uint_t uart_rx_any(pyb_uart_obj_t *self) {
        int buffer_bytes = self->read_buf_head - self->read_buf_tail;
        if (buffer_bytes < 0) {
            return buffer_bytes + self->read_buf_len;
        } else if (buffer_bytes > 0) {
            return buffer_bytes;
        } else {
            return __HAL_UART_GET_FLAG(&self->uart, UART_FLAG_RXNE) != RESET;
        }
    }
    
    // Waits at most timeout milliseconds for at least 1 char to become ready for
    // reading (from buf or for direct reading).
    // Returns true if something available, false if not.
    STATIC bool uart_rx_wait(pyb_uart_obj_t *self, uint32_t timeout) {
        uint32_t start = HAL_GetTick();
        for (;;) {
            if (self->read_buf_tail != self->read_buf_head || __HAL_UART_GET_FLAG(&self->uart, UART_FLAG_RXNE) != RESET) {
                return true; // have at least 1 char ready for reading
            }
            if (HAL_GetTick() - start >= timeout) {
                return false; // timeout
            }
            __WFI();
        }
    }
    
    // assumes there is a character available
    int uart_rx_char(pyb_uart_obj_t *self) {
        if (self->read_buf_tail != self->read_buf_head) {
            // buffering via IRQ
            int data;
            if (self->char_width == CHAR_WIDTH_9BIT) {
                data = ((uint16_t*)self->read_buf)[self->read_buf_tail];
            } else {
                data = self->read_buf[self->read_buf_tail];
            }
            self->read_buf_tail = (self->read_buf_tail + 1) % self->read_buf_len;
            if (__HAL_UART_GET_FLAG(&self->uart, UART_FLAG_RXNE) != RESET) {
                // UART was stalled by flow ctrl: re-enable IRQ now we have room in buffer
                __HAL_UART_ENABLE_IT(&self->uart, UART_IT_RXNE);
            }
            return data;
        } else {
            // no buffering
            #if defined(MCU_SERIES_F7) || defined(MCU_SERIES_L4)
            return self->uart.Instance->RDR & self->char_mask;
            #else
            return self->uart.Instance->DR & self->char_mask;
            #endif
        }
    }
    
    // Waits at most timeout milliseconds for TX register to become empty.
    // Returns true if can write, false if can't.
    STATIC bool uart_tx_wait(pyb_uart_obj_t *self, uint32_t timeout) {
        uint32_t start = HAL_GetTick();
        for (;;) {
            if (__HAL_UART_GET_FLAG(&self->uart, UART_FLAG_TXE)) {
                return true; // tx register is empty
            }
            if (HAL_GetTick() - start >= timeout) {
                return false; // timeout
            }
            __WFI();
        }
    }
    
    STATIC HAL_StatusTypeDef uart_tx_data(pyb_uart_obj_t *self, uint8_t *data, uint16_t len) {
        if (self->uart.Init.HwFlowCtl & UART_HWCONTROL_CTS) {
            // CTS can hold off transmission for an arbitrarily long time. Apply
            // the overall timeout rather than the character timeout.
            return HAL_UART_Transmit(&self->uart, data, len, self->timeout);
        }
        // The timeout specified here is for waiting for the TX data register to
        // become empty (ie between chars), as well as for the final char to be
        // completely transferred.  The default value for timeout_char is long
        // enough for 1 char, but we need to double it to wait for the last char
        // to be transferred to the data register, and then to be transmitted.
        return HAL_UART_Transmit(&self->uart, data, len, 2 * self->timeout_char);
    }
    
    STATIC void uart_tx_char(pyb_uart_obj_t *uart_obj, int c) {
        uint8_t ch = c;
        uart_tx_data(uart_obj, &ch, 1);
    }
    
    void uart_tx_strn(pyb_uart_obj_t *uart_obj, const char *str, uint len) {
        uart_tx_data(uart_obj, (uint8_t*)str, len);
    }
    
    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);
        }
    }
    
    // this IRQ handler is set up to handle RXNE interrupts only
    void uart_irq_handler(mp_uint_t uart_id) {
        // get the uart object
        pyb_uart_obj_t *self = MP_STATE_PORT(pyb_uart_obj_all)[uart_id - 1];
    
        if (self == NULL) {
            // UART object has not been set, so we can't do anything, not
            // even disable the IRQ.  This should never happen.
            return;
        }
    
        if (__HAL_UART_GET_FLAG(&self->uart, UART_FLAG_RXNE) != RESET) {
            if (self->read_buf_len != 0) {
                uint16_t next_head = (self->read_buf_head + 1) % self->read_buf_len;
                if (next_head != self->read_buf_tail) {
                    // only read data if room in buf
                    #if defined(MCU_SERIES_F7) || defined(MCU_SERIES_L4)
                    int data = self->uart.Instance->RDR; // clears UART_FLAG_RXNE
                    #else
                    int data = self->uart.Instance->DR; // clears UART_FLAG_RXNE
                    #endif
                    data &= self->char_mask;
                    if (self->char_width == CHAR_WIDTH_9BIT) {
                        ((uint16_t*)self->read_buf)[self->read_buf_head] = data;
                    } else {
                        self->read_buf[self->read_buf_head] = data;
                    }
                    self->read_buf_head = next_head;
                } else { // No room: leave char in buf, disable interrupt
                    __HAL_UART_DISABLE_IT(&self->uart, UART_IT_RXNE);
                }
            }
        }
    }
    
    /******************************************************************************/
    /* Micro Python bindings                                                      */
    
    STATIC void pyb_uart_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
        pyb_uart_obj_t *self = self_in;
        if (!self->is_enabled) {
            mp_printf(print, "UART(%u)", self->uart_id);
        } else {
            mp_int_t bits = (self->uart.Init.WordLength == UART_WORDLENGTH_8B ? 8 : 9);
            if (self->uart.Init.Parity != UART_PARITY_NONE) {
                bits -= 1;
            }
            mp_printf(print, "UART(%u, baudrate=%u, bits=%u, parity=",
                self->uart_id, self->uart.Init.BaudRate, bits);
            if (self->uart.Init.Parity == UART_PARITY_NONE) {
                mp_print_str(print, "None");
            } else {
                mp_printf(print, "%u", self->uart.Init.Parity == UART_PARITY_EVEN ? 0 : 1);
            }
            if (self->uart.Init.HwFlowCtl) {
                mp_printf(print, ", flow=");
                if (self->uart.Init.HwFlowCtl & UART_HWCONTROL_RTS) {
                    mp_printf(print, "RTS%s", self->uart.Init.HwFlowCtl & UART_HWCONTROL_CTS ? "|" : "");
                }
                if (self->uart.Init.HwFlowCtl & UART_HWCONTROL_CTS) {
                    mp_printf(print, "CTS");
                }
            }
            mp_printf(print, ", stop=%u, timeout=%u, timeout_char=%u, read_buf_len=%u)",
                self->uart.Init.StopBits == UART_STOPBITS_1 ? 1 : 2,
                self->timeout, self->timeout_char,
                self->read_buf_len == 0 ? 0 : self->read_buf_len - 1); // -1 to adjust for usable length of buffer
        }
    }
    
    /// \method init(baudrate, bits=8, parity=None, stop=1, *, timeout=1000, timeout_char=0, flow=0, read_buf_len=64)
    ///
    /// Initialise the UART bus with the given parameters:
    ///
    ///   - `baudrate` is the clock rate.
    ///   - `bits` is the number of bits per byte, 7, 8 or 9.
    ///   - `parity` is the parity, `None`, 0 (even) or 1 (odd).
    ///   - `stop` is the number of stop bits, 1 or 2.
    ///   - `timeout` is the timeout in milliseconds to wait for the first character.
    ///   - `timeout_char` is the timeout in milliseconds to wait between characters.
    ///   - `flow` is RTS | CTS where RTS == 256, CTS == 512
    ///   - `read_buf_len` is the character length of the read buffer (0 to disable).
    STATIC mp_obj_t pyb_uart_init_helper(pyb_uart_obj_t *self, mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
        static const mp_arg_t allowed_args[] = {
            { MP_QSTR_baudrate, MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = 9600} },
            { MP_QSTR_bits, MP_ARG_INT, {.u_int = 8} },
            { MP_QSTR_parity, MP_ARG_OBJ, {.u_obj = mp_const_none} },
            { MP_QSTR_stop, MP_ARG_INT, {.u_int = 1} },
            { MP_QSTR_flow, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = UART_HWCONTROL_NONE} },
            { MP_QSTR_timeout, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 1000} },
            { MP_QSTR_timeout_char, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
            { MP_QSTR_read_buf_len, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 64} },
        };
    
        // parse args
        struct {
            mp_arg_val_t baudrate, bits, parity, stop, flow, timeout, timeout_char, read_buf_len;
        } args;
        mp_arg_parse_all(n_args, pos_args, kw_args,
            MP_ARRAY_SIZE(allowed_args), allowed_args, (mp_arg_val_t*)&args);
    
        // set the UART configuration values
        memset(&self->uart, 0, sizeof(self->uart));
        UART_InitTypeDef *init = &self->uart.Init;
    
        // baudrate
        init->BaudRate = args.baudrate.u_int;
    
        // parity
        mp_int_t bits = args.bits.u_int;
        if (args.parity.u_obj == mp_const_none) {
            init->Parity = UART_PARITY_NONE;
        } else {
            mp_int_t parity = mp_obj_get_int(args.parity.u_obj);
            init->Parity = (parity & 1) ? UART_PARITY_ODD : UART_PARITY_EVEN;
            bits += 1; // STs convention has bits including parity
        }
    
        // number of bits
        if (bits == 8) {
            init->WordLength = UART_WORDLENGTH_8B;
        } else if (bits == 9) {
            init->WordLength = UART_WORDLENGTH_9B;
        } else {
            nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError, "unsupported combination of bits and parity"));
        }
    
        // stop bits
        switch (args.stop.u_int) {
            case 1: init->StopBits = UART_STOPBITS_1; break;
            default: init->StopBits = UART_STOPBITS_2; break;
        }
    
        // flow control
        init->HwFlowCtl = args.flow.u_int;
    
        // extra config (not yet configurable)
        init->Mode = UART_MODE_TX_RX;
        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(%d) does not exist", self->uart_id));
        }
    
        // set timeout
        self->timeout = args.timeout.u_int;
    
        // set timeout_char
        // make sure it is at least as long as a whole character (13 bits to be safe)
        self->timeout_char = args.timeout_char.u_int;
        uint32_t min_timeout_char = 13000 / init->BaudRate + 1;
        if (self->timeout_char < min_timeout_char) {
            self->timeout_char = min_timeout_char;
        }
    
        // setup the read buffer
        m_del(byte, self->read_buf, self->read_buf_len << self->char_width);
        if (init->WordLength == UART_WORDLENGTH_9B && init->Parity == UART_PARITY_NONE) {
            self->char_mask = 0x1ff;
            self->char_width = CHAR_WIDTH_9BIT;
        } else {
            if (init->WordLength == UART_WORDLENGTH_9B || init->Parity == UART_PARITY_NONE) {
                self->char_mask = 0xff;
            } else {
                self->char_mask = 0x7f;
            }
            self->char_width = CHAR_WIDTH_8BIT;
        }
        self->read_buf_head = 0;
        self->read_buf_tail = 0;
        if (args.read_buf_len.u_int <= 0) {
            // no read buffer
            self->read_buf_len = 0;
            self->read_buf = NULL;
            HAL_NVIC_DisableIRQ(self->irqn);
            __HAL_UART_DISABLE_IT(&self->uart, UART_IT_RXNE);
        } else {
            // read buffer using interrupts
            self->read_buf_len = args.read_buf_len.u_int + 1; // +1 to adjust for usable length of buffer
            self->read_buf = m_new(byte, self->read_buf_len << self->char_width);
            __HAL_UART_ENABLE_IT(&self->uart, UART_IT_RXNE);
            HAL_NVIC_SetPriority(self->irqn, IRQ_PRI_UART, IRQ_SUBPRI_UART); 
            HAL_NVIC_EnableIRQ(self->irqn);
        }
    
        // compute actual baudrate that was configured
        // (this formula assumes UART_OVERSAMPLING_16)
        uint32_t actual_baudrate;
        if (self->uart.Instance == USART1
            #if defined(USART6)
            || self->uart.Instance == USART6
            #endif
            ) {
            actual_baudrate = HAL_RCC_GetPCLK2Freq();
        } else {
            actual_baudrate = HAL_RCC_GetPCLK1Freq();
        }
        actual_baudrate /= self->uart.Instance->BRR;
    
        // check we could set the baudrate within 5%
        uint32_t baudrate_diff;
        if (actual_baudrate > init->BaudRate) {
            baudrate_diff = actual_baudrate - init->BaudRate;
        } else {
            baudrate_diff = init->BaudRate - actual_baudrate;
        }
        init->BaudRate = actual_baudrate; // remember actual baudrate for printing
        if (20 * baudrate_diff > init->BaudRate) {
            nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError, "set baudrate %d is not within 5%% of desired value", actual_baudrate));
        }
    
        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(const mp_obj_type_t *type, mp_uint_t n_args, mp_uint_t n_kw, const mp_obj_t *args) {
        // check arguments
        mp_arg_check_num(n_args, n_kw, 1, MP_OBJ_FUN_ARGS_MAX, true);
    
        // work out port
        int uart_id = 0;
        if (MP_OBJ_IS_STR(args[0])) {
            const char *port = mp_obj_str_get_str(args[0]);
            if (0) {
            #ifdef MICROPY_HW_UART1_NAME
            } else if (strcmp(port, MICROPY_HW_UART1_NAME) == 0) {
                uart_id = PYB_UART_1;
            #endif
            #ifdef MICROPY_HW_UART2_NAME
            } else if (strcmp(port, MICROPY_HW_UART2_NAME) == 0) {
                uart_id = PYB_UART_2;
            #endif
            #ifdef MICROPY_HW_UART3_NAME
            } else if (strcmp(port, MICROPY_HW_UART3_NAME) == 0) {
                uart_id = PYB_UART_3;
            #endif
            #ifdef MICROPY_HW_UART4_NAME
            } else if (strcmp(port, MICROPY_HW_UART4_NAME) == 0) {
                uart_id = PYB_UART_4;
            #endif
            #ifdef MICROPY_HW_UART5_NAME
            } else if (strcmp(port, MICROPY_HW_UART5_NAME) == 0) {
                uart_id = PYB_UART_5;
            #endif
            #ifdef MICROPY_HW_UART6_NAME
            } else if (strcmp(port, MICROPY_HW_UART6_NAME) == 0) {
                uart_id = PYB_UART_6;
            #endif
            } else {
                nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError, "UART(%s) does not exist", port));
            }
        } else {
            uart_id = mp_obj_get_int(args[0]);
            if (uart_id < 1 || uart_id > MP_ARRAY_SIZE(MP_STATE_PORT(pyb_uart_obj_all))) {
                nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError, "UART(%d) does not exist", uart_id));
            }
        }
    
        pyb_uart_obj_t *self;
        if (MP_STATE_PORT(pyb_uart_obj_all)[uart_id - 1] == NULL) {
            // create new UART object
            self = m_new0(pyb_uart_obj_t, 1);
            self->base.type = &pyb_uart_type;
            self->uart_id = uart_id;
            MP_STATE_PORT(pyb_uart_obj_all)[uart_id - 1] = self;
        } else {
            // reference existing UART object
            self = MP_STATE_PORT(pyb_uart_obj_all)[uart_id - 1];
        }
    
        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(self, n_args - 1, args + 1, &kw_args);
        }
    
        return self;
    }
    
    STATIC mp_obj_t pyb_uart_init(mp_uint_t 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;
        self->is_enabled = false;
        UART_HandleTypeDef *uart = &self->uart;
        HAL_UART_DeInit(uart);
        if (uart->Instance == USART1) {
            HAL_NVIC_DisableIRQ(USART1_IRQn);
            __USART1_FORCE_RESET();
            __USART1_RELEASE_RESET();
            __USART1_CLK_DISABLE();
        } else if (uart->Instance == USART2) {
            HAL_NVIC_DisableIRQ(USART2_IRQn);
            __USART2_FORCE_RESET();
            __USART2_RELEASE_RESET();
            __USART2_CLK_DISABLE();
        #if defined(USART3)
        } else if (uart->Instance == USART3) {
            HAL_NVIC_DisableIRQ(USART3_IRQn);
            __USART3_FORCE_RESET();
            __USART3_RELEASE_RESET();
            __USART3_CLK_DISABLE();
        #endif
        #if defined(UART4)
        } else if (uart->Instance == UART4) {
            HAL_NVIC_DisableIRQ(UART4_IRQn);
            __UART4_FORCE_RESET();
            __UART4_RELEASE_RESET();
            __UART4_CLK_DISABLE();
        #endif
        #if defined(UART5)
        } else if (uart->Instance == UART5) {
            HAL_NVIC_DisableIRQ(UART5_IRQn);
            __UART5_FORCE_RESET();
            __UART5_RELEASE_RESET();
            __UART5_CLK_DISABLE();
        #endif
        #if defined(UART6)
        } else if (uart->Instance == USART6) {
            HAL_NVIC_DisableIRQ(USART6_IRQn);
            __USART6_FORCE_RESET();
            __USART6_RELEASE_RESET();
            __USART6_CLK_DISABLE();
        #endif
        }
        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;
        return MP_OBJ_NEW_SMALL_INT(uart_rx_any(self));
    }
    STATIC MP_DEFINE_CONST_FUN_OBJ_1(pyb_uart_any_obj, pyb_uart_any);
    
    /// \method writechar(char)
    /// Write a single character on the bus.  `char` is an integer to write.
    /// Return value: `None`.
    STATIC mp_obj_t pyb_uart_writechar(mp_obj_t self_in, mp_obj_t char_in) {
        pyb_uart_obj_t *self = self_in;
    
        // get the character to write (might be 9 bits)
        uint16_t data = mp_obj_get_int(char_in);
    
        // write the character
        HAL_StatusTypeDef status;
        if (uart_tx_wait(self, self->timeout)) {
            status = uart_tx_data(self, (uint8_t*)&data, 1);
        } else {
            status = HAL_TIMEOUT;
        }
    
        if (status != HAL_OK) {
            mp_hal_raise(status);
        }
    
        return mp_const_none;
    }
    STATIC MP_DEFINE_CONST_FUN_OBJ_2(pyb_uart_writechar_obj, pyb_uart_writechar);
    
    /// \method readchar()
    /// Receive a single character on the bus.
    /// Return value: The character read, as an integer.  Returns -1 on timeout.
    STATIC mp_obj_t pyb_uart_readchar(mp_obj_t self_in) {
        pyb_uart_obj_t *self = self_in;
        if (uart_rx_wait(self, self->timeout)) {
            return MP_OBJ_NEW_SMALL_INT(uart_rx_char(self));
        } else {
            // return -1 on timeout
            return MP_OBJ_NEW_SMALL_INT(-1);
        }
    }
    STATIC MP_DEFINE_CONST_FUN_OBJ_1(pyb_uart_readchar_obj, pyb_uart_readchar);
    
    // uart.sendbreak()
    STATIC mp_obj_t pyb_uart_sendbreak(mp_obj_t self_in) {
        pyb_uart_obj_t *self = self_in;
        #if defined(MCU_SERIES_F7) || defined(MCU_SERIES_L4)
        self->uart.Instance->RQR = USART_RQR_SBKRQ; // write-only register
        #else
        self->uart.Instance->CR1 |= USART_CR1_SBK;
        #endif
        return mp_const_none;
    }
    STATIC MP_DEFINE_CONST_FUN_OBJ_1(pyb_uart_sendbreak_obj, pyb_uart_sendbreak);
    
    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 },
    
        /// \method read([nbytes])
        { MP_OBJ_NEW_QSTR(MP_QSTR_read), (mp_obj_t)&mp_stream_read_obj },
        /// \method readall()
        { MP_OBJ_NEW_QSTR(MP_QSTR_readall), (mp_obj_t)&mp_stream_readall_obj },
        /// \method readline()
        { MP_OBJ_NEW_QSTR(MP_QSTR_readline), (mp_obj_t)&mp_stream_unbuffered_readline_obj},
        /// \method readinto(buf[, nbytes])
        { MP_OBJ_NEW_QSTR(MP_QSTR_readinto), (mp_obj_t)&mp_stream_readinto_obj },
        /// \method write(buf)
        { MP_OBJ_NEW_QSTR(MP_QSTR_write), (mp_obj_t)&mp_stream_write_obj },
    
        { MP_OBJ_NEW_QSTR(MP_QSTR_writechar), (mp_obj_t)&pyb_uart_writechar_obj },
        { MP_OBJ_NEW_QSTR(MP_QSTR_readchar), (mp_obj_t)&pyb_uart_readchar_obj },
        { MP_OBJ_NEW_QSTR(MP_QSTR_sendbreak), (mp_obj_t)&pyb_uart_sendbreak_obj },
    
        // class constants
        { MP_OBJ_NEW_QSTR(MP_QSTR_RTS), MP_OBJ_NEW_SMALL_INT(UART_HWCONTROL_RTS) },
        { MP_OBJ_NEW_QSTR(MP_QSTR_CTS), MP_OBJ_NEW_SMALL_INT(UART_HWCONTROL_CTS) },
    };
    
    STATIC MP_DEFINE_CONST_DICT(pyb_uart_locals_dict, pyb_uart_locals_dict_table);
    
    STATIC mp_uint_t pyb_uart_read(mp_obj_t self_in, void *buf_in, mp_uint_t size, int *errcode) {
        pyb_uart_obj_t *self = self_in;
        byte *buf = buf_in;
    
        // check that size is a multiple of character width
        if (size & self->char_width) {
            *errcode = MP_EIO;
            return MP_STREAM_ERROR;
        }
    
        // convert byte size to char size
        size >>= self->char_width;
    
        // make sure we want at least 1 char
        if (size == 0) {
            return 0;
        }
    
        // wait for first char to become available
        if (!uart_rx_wait(self, self->timeout)) {
            // return EAGAIN error to indicate non-blocking (then read() method returns None)
            *errcode = MP_EAGAIN;
            return MP_STREAM_ERROR;
        }
    
        // read the data
        byte *orig_buf = buf;
        for (;;) {
            int data = uart_rx_char(self);
            if (self->char_width == CHAR_WIDTH_9BIT) {
                *(uint16_t*)buf = data;
                buf += 2;
            } else {
                *buf++ = data;
            }
            if (--size == 0 || !uart_rx_wait(self, self->timeout_char)) {
                // return number of bytes read
                return buf - orig_buf;
            }
        }
    }
    
    STATIC mp_uint_t pyb_uart_write(mp_obj_t self_in, const void *buf_in, mp_uint_t size, int *errcode) {
        pyb_uart_obj_t *self = self_in;
        const byte *buf = buf_in;
    
        // check that size is a multiple of character width
        if (size & self->char_width) {
            *errcode = MP_EIO;
            return MP_STREAM_ERROR;
        }
    
        // wait to be able to write the first character. EAGAIN causes write to return None
        if (!uart_tx_wait(self, self->timeout)) {
            *errcode = MP_EAGAIN;
            return MP_STREAM_ERROR;
        }
    
        // write the data
        HAL_StatusTypeDef status = uart_tx_data(self, (uint8_t*)buf, size >> self->char_width);
    
        if (status == HAL_OK) {
            // return number of bytes written
            return size;
        } else if (status == HAL_TIMEOUT) { // UART_WaitOnFlagUntilTimeout() disables RXNE interrupt on timeout
            if (self->read_buf_len > 0) {
                __HAL_UART_ENABLE_IT(&self->uart, UART_IT_RXNE); // re-enable RXNE
            }
            // return number of bytes written
            if (self->char_width == CHAR_WIDTH_8BIT) {
                return size - self->uart.TxXferCount - 1;
            } else {
                int written = self->uart.TxXferCount * 2;
                return size - written - 2;
            }
        } else {
            *errcode = mp_hal_status_to_errno_table[status];
            return MP_STREAM_ERROR;
        }
    }
    
    STATIC mp_uint_t pyb_uart_ioctl(mp_obj_t self_in, mp_uint_t request, mp_uint_t arg, int *errcode) {
        pyb_uart_obj_t *self = self_in;
        mp_uint_t ret;
        if (request == MP_IOCTL_POLL) {
            mp_uint_t flags = arg;
            ret = 0;
            if ((flags & MP_IOCTL_POLL_RD) && uart_rx_any(self)) {
                ret |= MP_IOCTL_POLL_RD;
            }
            if ((flags & MP_IOCTL_POLL_WR) && __HAL_UART_GET_FLAG(&self->uart, UART_FLAG_TXE)) {
                ret |= MP_IOCTL_POLL_WR;
            }
        } else {
            *errcode = MP_EINVAL;
            ret = MP_STREAM_ERROR;
        }
        return ret;
    }
    
    STATIC const mp_stream_p_t uart_stream_p = {
        .read = pyb_uart_read,
        .write = pyb_uart_write,
        .ioctl = pyb_uart_ioctl,
        .is_text = false,
    };
    
    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,
        .getiter = mp_identity,
        .iternext = mp_stream_unbuffered_iter,
        .stream_p = &uart_stream_p,
        .locals_dict = (mp_obj_t)&pyb_uart_locals_dict,
    };