path: root/ports/stm32/uart.c

/*
 * This file is part of the MicroPython 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/runtime.h"
#include "py/stream.h"
#include "py/mperrno.h"
#include "py/mphal.h"
#include "shared/runtime/interrupt_char.h"
#include "shared/runtime/mpirq.h"
#include "uart.h"
#include "irq.h"
#include "pendsv.h"

#if defined(STM32F4) || defined(STM32L1)
#define UART_RXNE_IS_SET(uart) ((uart)->SR & USART_SR_RXNE)
#else
#if defined(STM32G0) || defined(STM32H7) || defined(STM32WL)
#define USART_ISR_RXNE USART_ISR_RXNE_RXFNE
#endif
#define UART_RXNE_IS_SET(uart) ((uart)->ISR & USART_ISR_RXNE)
#endif

#if defined(STM32G0) || defined(STM32WL)
#define UART_RXNE_IT_EN(uart) do { (uart)->CR1 |= USART_CR1_RXNEIE_RXFNEIE; } while (0)
#define UART_RXNE_IT_DIS(uart) do { (uart)->CR1 &= ~USART_CR1_RXNEIE_RXFNEIE; } while (0)
#else
#define UART_RXNE_IT_EN(uart) do { (uart)->CR1 |= USART_CR1_RXNEIE; } while (0)
#define UART_RXNE_IT_DIS(uart) do { (uart)->CR1 &= ~USART_CR1_RXNEIE; } while (0)
#endif

#if defined(STM32G0) || defined(STM32WL)
#define USART_CR1_IE_BASE (USART_CR1_PEIE | USART_CR1_TXEIE_TXFNFIE | USART_CR1_TCIE | USART_CR1_RXNEIE_RXFNEIE | USART_CR1_IDLEIE)
#else
#define USART_CR1_IE_BASE (USART_CR1_PEIE | USART_CR1_TXEIE | USART_CR1_TCIE | USART_CR1_RXNEIE | USART_CR1_IDLEIE)
#endif
#define USART_CR2_IE_BASE (USART_CR2_LBDIE)
#define USART_CR3_IE_BASE (USART_CR3_CTSIE | USART_CR3_EIE)

#if defined(STM32F0)
#define USART_CR1_IE_ALL (USART_CR1_IE_BASE | USART_CR1_EOBIE | USART_CR1_RTOIE | USART_CR1_CMIE)
#define USART_CR2_IE_ALL (USART_CR2_IE_BASE)
#define USART_CR3_IE_ALL (USART_CR3_IE_BASE | USART_CR3_WUFIE)

#elif defined(STM32F4)
#define USART_CR1_IE_ALL (USART_CR1_IE_BASE)
#define USART_CR2_IE_ALL (USART_CR2_IE_BASE)
#define USART_CR3_IE_ALL (USART_CR3_IE_BASE)

#elif defined(STM32F7)
#define USART_CR1_IE_ALL (USART_CR1_IE_BASE | USART_CR1_EOBIE | USART_CR1_RTOIE | USART_CR1_CMIE)
#define USART_CR2_IE_ALL (USART_CR2_IE_BASE)
#if defined(USART_CR3_TCBGTIE)
#define USART_CR3_IE_ALL (USART_CR3_IE_BASE | USART_CR3_TCBGTIE)
#else
#define USART_CR3_IE_ALL (USART_CR3_IE_BASE)
#endif

#elif defined(STM32G0) || defined(STM32G4) || defined(STM32H5)
#define USART_CR1_IE_ALL (USART_CR1_IE_BASE | USART_CR1_EOBIE | USART_CR1_RTOIE | USART_CR1_CMIE)
#define USART_CR2_IE_ALL (USART_CR2_IE_BASE)
#if defined(USART_CR3_TCBGTIE)
#define USART_CR3_IE_ALL (USART_CR3_IE_BASE | USART_CR3_TCBGTIE | USART_CR3_WUFIE)
#else
#define USART_CR3_IE_ALL (USART_CR3_IE_BASE | USART_CR3_WUFIE)
#endif

#elif defined(STM32H7) || defined(STM32N6)
#define USART_CR1_IE_ALL (USART_CR1_IE_BASE | USART_CR1_RXFFIE | USART_CR1_TXFEIE | USART_CR1_EOBIE | USART_CR1_RTOIE | USART_CR1_CMIE)
#define USART_CR2_IE_ALL (USART_CR2_IE_BASE)
#define USART_CR3_IE_ALL (USART_CR3_IE_BASE | USART_CR3_RXFTIE | USART_CR3_TCBGTIE | USART_CR3_TXFTIE | USART_CR3_WUFIE)

#elif defined(STM32L0)
#define USART_CR1_IE_ALL (USART_CR1_IE_BASE | USART_CR1_EOBIE | USART_CR1_RTOIE | USART_CR1_CMIE)
#define USART_CR2_IE_ALL (USART_CR2_IE_BASE)
#define USART_CR3_IE_ALL (USART_CR3_IE_BASE | USART_CR3_WUFIE)

#elif defined(STM32L1)
#define USART_CR1_IE_ALL (USART_CR1_IE_BASE)
#define USART_CR2_IE_ALL (USART_CR2_IE_BASE)
#define USART_CR3_IE_ALL (USART_CR3_IE_BASE)

#elif defined(STM32L4) || defined(STM32WB) || defined(STM32WL)
#define USART_CR1_IE_ALL (USART_CR1_IE_BASE | USART_CR1_EOBIE | USART_CR1_RTOIE | USART_CR1_CMIE)
#define USART_CR2_IE_ALL (USART_CR2_IE_BASE)
#if defined(USART_CR3_TCBGTIE)
#define USART_CR3_IE_ALL (USART_CR3_IE_BASE | USART_CR3_TCBGTIE | USART_CR3_WUFIE)
#else
#define USART_CR3_IE_ALL (USART_CR3_IE_BASE | USART_CR3_WUFIE)
#endif

#endif

typedef struct _machine_uart_irq_map_t {
    uint16_t irq_en;
    uint16_t flag;
} machine_uart_irq_map_t;

static const machine_uart_irq_map_t mp_uart_irq_map[] = {
    { USART_CR1_IDLEIE, UART_FLAG_IDLE}, // RX idle
    { USART_CR1_PEIE,   UART_FLAG_PE},   // parity error
    #if defined(STM32G0) || defined(STM32WL)
    { USART_CR1_TXEIE_TXFNFIE, UART_FLAG_TXE}, // TX register empty
    #else
    { USART_CR1_TXEIE,  UART_FLAG_TXE},  // TX register empty
    #endif
    { USART_CR1_TCIE,   UART_FLAG_TC},   // TX complete
    #if defined(STM32G0) || defined(STM32WL)
    { USART_CR1_RXNEIE_RXFNEIE, UART_FLAG_RXNE}, // RX register not empty
    #else
    { USART_CR1_RXNEIE, UART_FLAG_RXNE}, // RX register not empty
    #endif
    #if 0
    // For now only IRQs selected by CR1 are supported
    #if defined(STM32F4)
    { USART_CR2_LBDIE,  UART_FLAG_LBD},  // LIN break detection
    #else
    { USART_CR2_LBDIE,  UART_FLAG_LBDF}, // LIN break detection
    #endif
    { USART_CR3_CTSIE,  UART_FLAG_CTS},  // CTS
    #endif
};

void uart_init0(void) {
    #if defined(STM32H7)
    RCC_PeriphCLKInitTypeDef RCC_PeriphClkInit = {0};
    // Configure USART1/6 and USART2/3/4/5/7/8 clock sources
    RCC_PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_USART16 | RCC_PERIPHCLK_USART234578;
    RCC_PeriphClkInit.Usart16ClockSelection = RCC_USART16CLKSOURCE_D2PCLK2;
    RCC_PeriphClkInit.Usart234578ClockSelection = RCC_USART234578CLKSOURCE_D2PCLK1;
    if (HAL_RCCEx_PeriphCLKConfig(&RCC_PeriphClkInit) != HAL_OK) {
        MICROPY_BOARD_FATAL_ERROR("HAL_RCCEx_PeriphCLKConfig");
    }
    #elif defined(STM32N6)
    // UART clock configuration, IC14 (max 100MHz).
    LL_RCC_SetUSARTClockSource(LL_RCC_USART1_CLKSOURCE_IC14);
    LL_RCC_SetUSARTClockSource(LL_RCC_USART2_CLKSOURCE_IC14);
    LL_RCC_SetUSARTClockSource(LL_RCC_USART3_CLKSOURCE_IC14);
    LL_RCC_SetUARTClockSource(LL_RCC_UART4_CLKSOURCE_IC14);
    LL_RCC_SetUARTClockSource(LL_RCC_UART5_CLKSOURCE_IC14);
    LL_RCC_SetUSARTClockSource(LL_RCC_USART6_CLKSOURCE_IC14);
    LL_RCC_SetUARTClockSource(LL_RCC_UART7_CLKSOURCE_IC14);
    LL_RCC_SetUARTClockSource(LL_RCC_UART8_CLKSOURCE_IC14);
    LL_RCC_SetUARTClockSource(LL_RCC_UART9_CLKSOURCE_IC14);
    LL_RCC_SetUSARTClockSource(LL_RCC_USART10_CLKSOURCE_IC14);
    #endif
}

// unregister all interrupt sources
void uart_deinit_all(void) {
    for (int i = 0; i < MP_ARRAY_SIZE(MP_STATE_PORT(machine_uart_obj_all)); i++) {
        machine_uart_obj_t *uart_obj = MP_STATE_PORT(machine_uart_obj_all)[i];
        if (uart_obj != NULL && !uart_obj->is_static) {
            uart_deinit(uart_obj);
            MP_STATE_PORT(machine_uart_obj_all)[i] = NULL;
        }
    }
}

bool uart_exists(int uart_id) {
    if (uart_id > MP_ARRAY_SIZE(MP_STATE_PORT(machine_uart_obj_all))) {
        // safeguard against machine_uart_obj_all array being configured too small
        return false;
    }
    switch (uart_id) {
        #if defined(MICROPY_HW_UART1_TX) && defined(MICROPY_HW_UART1_RX)
        case PYB_UART_1:
            return true;
        #endif

        #if defined(MICROPY_HW_UART2_TX) && defined(MICROPY_HW_UART2_RX)
        case PYB_UART_2:
            return true;
        #endif

        #if defined(MICROPY_HW_UART3_TX) && defined(MICROPY_HW_UART3_RX)
        case PYB_UART_3:
            return true;
        #endif

        #if defined(MICROPY_HW_UART4_TX) && defined(MICROPY_HW_UART4_RX)
        case PYB_UART_4:
            return true;
        #endif

        #if defined(MICROPY_HW_UART5_TX) && defined(MICROPY_HW_UART5_RX)
        case PYB_UART_5:
            return true;
        #endif

        #if defined(MICROPY_HW_UART6_TX) && defined(MICROPY_HW_UART6_RX)
        case PYB_UART_6:
            return true;
        #endif

        #if defined(MICROPY_HW_UART7_TX) && defined(MICROPY_HW_UART7_RX)
        case PYB_UART_7:
            return true;
        #endif

        #if defined(MICROPY_HW_UART8_TX) && defined(MICROPY_HW_UART8_RX)
        case PYB_UART_8:
            return true;
        #endif

        #if defined(MICROPY_HW_UART9_TX) && defined(MICROPY_HW_UART9_RX)
        case PYB_UART_9:
            return true;
        #endif

        #if defined(MICROPY_HW_UART10_TX) && defined(MICROPY_HW_UART10_RX)
        case PYB_UART_10:
            return true;
        #endif

        #if defined(MICROPY_HW_LPUART1_TX) && defined(MICROPY_HW_LPUART1_RX)
        case PYB_LPUART_1:
            return true;
        #endif

        #if defined(MICROPY_HW_LPUART2_TX) && defined(MICROPY_HW_LPUART2_RX)
        case PYB_LPUART_2:
            return true;
        #endif

        default:
            return false;
    }
}

// assumes Init parameters have been set up correctly
bool uart_init(machine_uart_obj_t *uart_obj,
    uint32_t baudrate, uint32_t bits, uint32_t parity, uint32_t stop, uint32_t flow) {
    USART_TypeDef *UARTx;
    IRQn_Type irqn;
    uint8_t uart_fn = AF_FN_UART;
    int uart_unit;

    const machine_pin_obj_t *pins[4] = {0};

    // Default pull is pull-up on RX and CTS (the input pins).
    uint32_t pins_pull[4] = { GPIO_NOPULL, GPIO_PULLUP, GPIO_NOPULL, GPIO_PULLUP };

    switch (uart_obj->uart_id) {
        #if defined(MICROPY_HW_UART1_TX) && defined(MICROPY_HW_UART1_RX)
        case PYB_UART_1:
            uart_unit = 1;
            UARTx = USART1;
            irqn = USART1_IRQn;
            pins[0] = MICROPY_HW_UART1_TX;
            pins[1] = MICROPY_HW_UART1_RX;
            #if defined(MICROPY_HW_UART1_RTS)
            if (flow & UART_HWCONTROL_RTS) {
                pins[2] = MICROPY_HW_UART1_RTS;
            }
            #endif
            #if defined(MICROPY_HW_UART1_CTS)
            if (flow & UART_HWCONTROL_CTS) {
                pins[3] = MICROPY_HW_UART1_CTS;
            }
            #endif
            #if defined(MICROPY_HW_UART1_RX_PULL)
            pins_pull[1] = MICROPY_HW_UART1_RX_PULL;
            #endif
            #if defined(MICROPY_HW_UART1_CTS_PULL)
            pins_pull[3] = MICROPY_HW_UART1_CTS_PULL;
            #endif
            __HAL_RCC_USART1_CLK_ENABLE();
            break;
        #endif

        #if defined(MICROPY_HW_UART2_TX) && defined(MICROPY_HW_UART2_RX)
        case PYB_UART_2:
            uart_unit = 2;
            UARTx = USART2;
            #if defined(STM32G0)
            irqn = USART2_LPUART2_IRQn;
            #else
            irqn = USART2_IRQn;
            #endif
            pins[0] = MICROPY_HW_UART2_TX;
            pins[1] = MICROPY_HW_UART2_RX;
            #if defined(MICROPY_HW_UART2_RTS)
            if (flow & UART_HWCONTROL_RTS) {
                pins[2] = MICROPY_HW_UART2_RTS;
            }
            #endif
            #if defined(MICROPY_HW_UART2_CTS)
            if (flow & UART_HWCONTROL_CTS) {
                pins[3] = MICROPY_HW_UART2_CTS;
            }
            #endif
            #if defined(MICROPY_HW_UART2_RX_PULL)
            pins_pull[1] = MICROPY_HW_UART2_RX_PULL;
            #endif
            #if defined(MICROPY_HW_UART2_CTS_PULL)
            pins_pull[3] = MICROPY_HW_UART2_CTS_PULL;
            #endif
            __HAL_RCC_USART2_CLK_ENABLE();
            break;
        #endif

        #if defined(MICROPY_HW_UART3_TX) && defined(MICROPY_HW_UART3_RX)
        case PYB_UART_3:
            uart_unit = 3;
            UARTx = USART3;
            #if defined(STM32F0)
            irqn = USART3_8_IRQn;
            #elif defined(STM32G0)
            irqn = USART3_4_5_6_LPUART1_IRQn;
            #else
            irqn = USART3_IRQn;
            #endif
            pins[0] = MICROPY_HW_UART3_TX;
            pins[1] = MICROPY_HW_UART3_RX;
            #if defined(MICROPY_HW_UART3_RTS)
            if (flow & UART_HWCONTROL_RTS) {
                pins[2] = MICROPY_HW_UART3_RTS;
            }
            #endif
            #if defined(MICROPY_HW_UART3_CTS)
            if (flow & UART_HWCONTROL_CTS) {
                pins[3] = MICROPY_HW_UART3_CTS;
            }
            #endif
            #if defined(MICROPY_HW_UART3_RX_PULL)
            pins_pull[1] = MICROPY_HW_UART3_RX_PULL;
            #endif
            #if defined(MICROPY_HW_UART3_CTS_PULL)
            pins_pull[3] = MICROPY_HW_UART3_CTS_PULL;
            #endif
            __HAL_RCC_USART3_CLK_ENABLE();
            break;
        #endif

        #if defined(MICROPY_HW_UART4_TX) && defined(MICROPY_HW_UART4_RX)
        case PYB_UART_4:
            uart_unit = 4;
            #if defined(STM32F0)
            UARTx = USART4;
            irqn = USART3_8_IRQn;
            __HAL_RCC_USART4_CLK_ENABLE();
            #elif defined(STM32L0)
            UARTx = USART4;
            irqn = USART4_5_IRQn;
            __HAL_RCC_USART4_CLK_ENABLE();
            #elif defined(STM32G0)
            UARTx = USART4;
            irqn = USART3_4_5_6_LPUART1_IRQn;
            __HAL_RCC_USART4_CLK_ENABLE();
            #else
            UARTx = UART4;
            irqn = UART4_IRQn;
            __HAL_RCC_UART4_CLK_ENABLE();
            #endif
            pins[0] = MICROPY_HW_UART4_TX;
            pins[1] = MICROPY_HW_UART4_RX;
            #if defined(MICROPY_HW_UART4_RTS)
            if (flow & UART_HWCONTROL_RTS) {
                pins[2] = MICROPY_HW_UART4_RTS;
            }
            #endif
            #if defined(MICROPY_HW_UART4_CTS)
            if (flow & UART_HWCONTROL_CTS) {
                pins[3] = MICROPY_HW_UART4_CTS;
            }
            #endif
            #if defined(MICROPY_HW_UART4_RX_PULL)
            pins_pull[1] = MICROPY_HW_UART4_RX_PULL;
            #endif
            #if defined(MICROPY_HW_UART4_CTS_PULL)
            pins_pull[3] = MICROPY_HW_UART4_CTS_PULL;
            #endif
            break;
        #endif

        #if defined(MICROPY_HW_UART5_TX) && defined(MICROPY_HW_UART5_RX)
        case PYB_UART_5:
            uart_unit = 5;
            #if defined(STM32F0)
            UARTx = USART5;
            irqn = USART3_8_IRQn;
            __HAL_RCC_USART5_CLK_ENABLE();
            #elif defined(STM32L0)
            UARTx = USART5;
            irqn = USART4_5_IRQn;
            __HAL_RCC_USART5_CLK_ENABLE();
            #elif defined(STM32G0)
            UARTx = USART5;
            irqn = USART3_4_5_6_LPUART1_IRQn;
            __HAL_RCC_USART5_CLK_ENABLE();
            #else
            UARTx = UART5;
            irqn = UART5_IRQn;
            __HAL_RCC_UART5_CLK_ENABLE();
            #endif
            pins[0] = MICROPY_HW_UART5_TX;
            pins[1] = MICROPY_HW_UART5_RX;
            #if defined(MICROPY_HW_UART5_RTS)
            if (flow & UART_HWCONTROL_RTS) {
                pins[2] = MICROPY_HW_UART5_RTS;
            }
            #endif
            #if defined(MICROPY_HW_UART5_CTS)
            if (flow & UART_HWCONTROL_CTS) {
                pins[3] = MICROPY_HW_UART5_CTS;
            }
            #endif
            #if defined(MICROPY_HW_UART5_RX_PULL)
            pins_pull[1] = MICROPY_HW_UART5_RX_PULL;
            #endif
            #if defined(MICROPY_HW_UART5_CTS_PULL)
            pins_pull[3] = MICROPY_HW_UART5_CTS_PULL;
            #endif
            break;
        #endif

        #if defined(MICROPY_HW_UART6_TX) && defined(MICROPY_HW_UART6_RX)
        case PYB_UART_6:
            uart_unit = 6;
            UARTx = USART6;
            #if defined(STM32F0)
            irqn = USART3_8_IRQn;
            #elif defined(STM32G0)
            irqn = USART3_4_5_6_LPUART1_IRQn;
            #else
            irqn = USART6_IRQn;
            #endif
            pins[0] = MICROPY_HW_UART6_TX;
            pins[1] = MICROPY_HW_UART6_RX;
            #if defined(MICROPY_HW_UART6_RTS)
            if (flow & UART_HWCONTROL_RTS) {
                pins[2] = MICROPY_HW_UART6_RTS;
            }
            #endif
            #if defined(MICROPY_HW_UART6_CTS)
            if (flow & UART_HWCONTROL_CTS) {
                pins[3] = MICROPY_HW_UART6_CTS;
            }
            #endif
            #if defined(MICROPY_HW_UART6_RX_PULL)
            pins_pull[1] = MICROPY_HW_UART6_RX_PULL;
            #endif
            #if defined(MICROPY_HW_UART6_CTS_PULL)
            pins_pull[3] = MICROPY_HW_UART6_CTS_PULL;
            #endif
            __HAL_RCC_USART6_CLK_ENABLE();
            break;
        #endif

        #if defined(MICROPY_HW_UART7_TX) && defined(MICROPY_HW_UART7_RX)
        case PYB_UART_7:
            uart_unit = 7;
            #if defined(STM32F0)
            UARTx = USART7;
            irqn = USART3_8_IRQn;
            __HAL_RCC_USART7_CLK_ENABLE();
            #else
            UARTx = UART7;
            irqn = UART7_IRQn;
            __HAL_RCC_UART7_CLK_ENABLE();
            #endif
            pins[0] = MICROPY_HW_UART7_TX;
            pins[1] = MICROPY_HW_UART7_RX;
            #if defined(MICROPY_HW_UART7_RTS)
            if (flow & UART_HWCONTROL_RTS) {
                pins[2] = MICROPY_HW_UART7_RTS;
            }
            #endif
            #if defined(MICROPY_HW_UART7_CTS)
            if (flow & UART_HWCONTROL_CTS) {
                pins[3] = MICROPY_HW_UART7_CTS;
            }
            #endif
            #if defined(MICROPY_HW_UART7_RX_PULL)
            pins_pull[1] = MICROPY_HW_UART7_RX_PULL;
            #endif
            #if defined(MICROPY_HW_UART7_CTS_PULL)
            pins_pull[3] = MICROPY_HW_UART7_CTS_PULL;
            #endif
            break;
        #endif

        #if defined(MICROPY_HW_UART8_TX) && defined(MICROPY_HW_UART8_RX)
        case PYB_UART_8:
            uart_unit = 8;
            #if defined(STM32F0)
            UARTx = USART8;
            irqn = USART3_8_IRQn;
            __HAL_RCC_USART8_CLK_ENABLE();
            #else
            UARTx = UART8;
            irqn = UART8_IRQn;
            __HAL_RCC_UART8_CLK_ENABLE();
            #endif
            pins[0] = MICROPY_HW_UART8_TX;
            pins[1] = MICROPY_HW_UART8_RX;
            #if defined(MICROPY_HW_UART8_RTS)
            if (flow & UART_HWCONTROL_RTS) {
                pins[2] = MICROPY_HW_UART8_RTS;
            }
            #endif
            #if defined(MICROPY_HW_UART8_CTS)
            if (flow & UART_HWCONTROL_CTS) {
                pins[3] = MICROPY_HW_UART8_CTS;
            }
            #endif
            #if defined(MICROPY_HW_UART8_RX_PULL)
            pins_pull[1] = MICROPY_HW_UART8_RX_PULL;
            #endif
            #if defined(MICROPY_HW_UART8_CTS_PULL)
            pins_pull[3] = MICROPY_HW_UART8_CTS_PULL;
            #endif
            break;
        #endif

        #if defined(MICROPY_HW_UART9_TX) && defined(MICROPY_HW_UART9_RX)
        case PYB_UART_9:
            uart_unit = 9;
            UARTx = UART9;
            irqn = UART9_IRQn;
            __HAL_RCC_UART9_CLK_ENABLE();
            pins[0] = MICROPY_HW_UART9_TX;
            pins[1] = MICROPY_HW_UART9_RX;
            #if defined(MICROPY_HW_UART9_RX_PULL)
            pins_pull[1] = MICROPY_HW_UART9_RX_PULL;
            #endif
            break;
        #endif

        #if defined(MICROPY_HW_UART10_TX) && defined(MICROPY_HW_UART10_RX)
        case PYB_UART_10:
            uart_unit = 10;
            #if defined(UART10)
            UARTx = UART10;
            irqn = UART10_IRQn;
            __HAL_RCC_UART10_CLK_ENABLE();
            #else
            UARTx = USART10;
            irqn = USART10_IRQn;
            __HAL_RCC_USART10_CLK_ENABLE();
            #endif
            pins[0] = MICROPY_HW_UART10_TX;
            pins[1] = MICROPY_HW_UART10_RX;
            #if defined(MICROPY_HW_UART10_RX_PULL)
            pins_pull[1] = MICROPY_HW_UART10_RX_PULL;
            #endif
            break;
        #endif

        #if defined(MICROPY_HW_LPUART1_TX) && defined(MICROPY_HW_LPUART1_RX)
        case PYB_LPUART_1:
            uart_fn = AF_FN_LPUART;
            uart_unit = 1;
            UARTx = LPUART1;
            #if defined(STM32G0)
            irqn = USART3_4_5_6_LPUART1_IRQn;
            #else
            irqn = LPUART1_IRQn;
            #endif
            pins[0] = MICROPY_HW_LPUART1_TX;
            pins[1] = MICROPY_HW_LPUART1_RX;
            #if defined(MICROPY_HW_LPUART1_RTS)
            if (flow & UART_HWCONTROL_RTS) {
                pins[2] = MICROPY_HW_LPUART1_RTS;
            }
            #endif
            #if defined(MICROPY_HW_LPUART1_CTS)
            if (flow & UART_HWCONTROL_CTS) {
                pins[3] = MICROPY_HW_LPUART1_CTS;
            }
            #endif
            #if defined(MICROPY_HW_LPUART1_RX_PULL)
            pins_pull[1] = MICROPY_HW_LPUART1_RX_PULL;
            #endif
            #if defined(MICROPY_HW_LPUART1_CTS_PULL)
            pins_pull[3] = MICROPY_HW_LPUART1_CTS_PULL;
            #endif
            __HAL_RCC_LPUART1_CLK_ENABLE();
            break;
        #endif

        #if defined(MICROPY_HW_LPUART2_TX) && defined(MICROPY_HW_LPUART2_RX)
        case PYB_LPUART_2:
            uart_fn = AF_FN_LPUART;
            uart_unit = 2;
            UARTx = LPUART2;
            #if defined(STM32G0)
            irqn = USART2_LPUART2_IRQn;
            #endif
            pins[0] = MICROPY_HW_LPUART2_TX;
            pins[1] = MICROPY_HW_LPUART2_RX;
            #if defined(MICROPY_HW_LPUART2_RTS)
            if (flow & UART_HWCONTROL_RTS) {
                pins[2] = MICROPY_HW_LPUART2_RTS;
            }
            #endif
            #if defined(MICROPY_HW_LPUART2_CTS)
            if (flow & UART_HWCONTROL_CTS) {
                pins[3] = MICROPY_HW_LPUART2_CTS;
            }
            #endif
            #if defined(MICROPY_HW_LPUART2_RX_PULL)
            pins_pull[1] = MICROPY_HW_LPUART2_RX_PULL;
            #endif
            #if defined(MICROPY_HW_LPUART2_CTS_PULL)
            pins_pull[3] = MICROPY_HW_LPUART2_CTS_PULL;
            #endif
            __HAL_RCC_LPUART2_CLK_ENABLE();
            break;
        #endif

        default:
            // UART does not exist or is not configured for this board
            return false;
    }

    uint32_t mode = MP_HAL_PIN_MODE_ALT;

    for (uint i = 0; i < 4; i++) {
        if (pins[i] != NULL) {
            if (!mp_hal_pin_config_alt(pins[i], mode, pins_pull[i], uart_fn, uart_unit)) {
                return false;
            }
        }
    }

    uart_obj->uartx = UARTx;

    // Set the initialisation parameters for the UART.
    UART_HandleTypeDef huart;
    memset(&huart, 0, sizeof(huart));
    huart.Instance = UARTx;
    huart.Init.BaudRate = baudrate;
    huart.Init.WordLength = bits;
    huart.Init.StopBits = stop;
    huart.Init.Parity = parity;
    huart.Init.Mode = UART_MODE_TX_RX;
    huart.Init.HwFlowCtl = flow;
    huart.Init.OverSampling = UART_OVERSAMPLING_16;

    #if defined(STM32G4) || defined(STM32H7) // WB also has a fifo..
    huart.FifoMode = UART_FIFOMODE_ENABLE;
    #endif

    #if !defined(STM32F4) && !defined(STM32L1)
    huart.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
    #endif

    #if defined(STM32H7) || defined(STM32N6) || defined(STM32WB)
    // Compute the smallest prescaler that will allow the given baudrate.
    uint32_t presc = UART_PRESCALER_DIV1;
    if (uart_obj->uart_id == PYB_LPUART_1) {
        uint32_t source_clk = uart_get_source_freq(uart_obj);
        for (; presc < UART_PRESCALER_DIV256; ++presc) {
            uint32_t brr = UART_DIV_LPUART(source_clk, baudrate, presc);
            if (brr <= LPUART_BRR_MASK) {
                break;
            }
        }
    }
    huart.Init.ClockPrescaler = presc;
    #endif

    // Initialise the UART hardware.
    HAL_UART_Init(&huart);

    // Disable all individual UART IRQs, but enable the global handler
    uart_obj->uartx->CR1 &= ~USART_CR1_IE_ALL;
    uart_obj->uartx->CR2 &= ~USART_CR2_IE_ALL;
    uart_obj->uartx->CR3 &= ~USART_CR3_IE_ALL;
    NVIC_SetPriority(IRQn_NONNEG(irqn), IRQ_PRI_UART);
    HAL_NVIC_EnableIRQ(irqn);

    uart_obj->is_enabled = true;
    uart_obj->attached_to_repl = false;

    #if defined(STM32F4) || defined(STM32L1)
    uart_obj->suppress_idle_irq = true;
    #endif

    if (bits == UART_WORDLENGTH_9B && parity == UART_PARITY_NONE) {
        uart_obj->char_mask = 0x1ff;
        uart_obj->char_width = CHAR_WIDTH_9BIT;
    } else {
        if (bits == UART_WORDLENGTH_9B || parity == UART_PARITY_NONE) {
            uart_obj->char_mask = 0xff;
        } else {
            uart_obj->char_mask = 0x7f;
        }
        uart_obj->char_width = CHAR_WIDTH_8BIT;
    }

    #if defined(STM32H7)
    HAL_UARTEx_SetTxFifoThreshold(&huart, UART_TXFIFO_THRESHOLD_1_8);
    HAL_UARTEx_SetRxFifoThreshold(&huart, UART_RXFIFO_THRESHOLD_1_8);
    HAL_UARTEx_EnableFifoMode(&huart);
    #endif

    uart_obj->mp_irq_trigger = 0;
    uart_obj->mp_irq_obj = NULL;

    return true;
}

void uart_irq_config(machine_uart_obj_t *self, bool enable) {
    if (self->mp_irq_trigger) {
        for (size_t entry = 0; entry < MP_ARRAY_SIZE(mp_uart_irq_map); ++entry) {
            if (mp_uart_irq_map[entry].flag & MP_UART_RESERVED_FLAGS) {
                continue;
            }
            if (mp_uart_irq_map[entry].flag & self->mp_irq_trigger) {
                if (enable) {
                    self->uartx->CR1 |= mp_uart_irq_map[entry].irq_en;
                } else {
                    self->uartx->CR1 &= ~mp_uart_irq_map[entry].irq_en;
                }
            }
        }
    }
}

void uart_set_rxbuf(machine_uart_obj_t *self, size_t len, void *buf) {
    self->read_buf_head = 0;
    self->read_buf_tail = 0;
    self->read_buf_len = len;
    self->read_buf = buf;
    if (len == 0) {
        UART_RXNE_IT_DIS(self->uartx);
    } else {
        UART_RXNE_IT_EN(self->uartx);
    }
}

void uart_deinit(machine_uart_obj_t *self) {
    self->is_enabled = false;

    // Disable UART
    self->uartx->CR1 &= ~USART_CR1_UE;

    // Reset and turn off the UART peripheral
    if (self->uart_id == 1) {
        HAL_NVIC_DisableIRQ(USART1_IRQn);
        __HAL_RCC_USART1_FORCE_RESET();
        __HAL_RCC_USART1_RELEASE_RESET();
        __HAL_RCC_USART1_CLK_DISABLE();
    #if defined(USART2)
    } else if (self->uart_id == 2) {
        #if defined(STM32G0)
        HAL_NVIC_DisableIRQ(USART2_LPUART2_IRQn);
        #else
        HAL_NVIC_DisableIRQ(USART2_IRQn);
        #endif
        __HAL_RCC_USART2_FORCE_RESET();
        __HAL_RCC_USART2_RELEASE_RESET();
        __HAL_RCC_USART2_CLK_DISABLE();
    #endif
    #if defined(USART3)
    } else if (self->uart_id == 3) {
        #if defined(STM32G0)
        HAL_NVIC_DisableIRQ(USART3_4_5_6_LPUART1_IRQn);
        #elif !defined(STM32F0)
        HAL_NVIC_DisableIRQ(USART3_IRQn);
        #endif
        __HAL_RCC_USART3_FORCE_RESET();
        __HAL_RCC_USART3_RELEASE_RESET();
        __HAL_RCC_USART3_CLK_DISABLE();
    #endif
    #if defined(UART4)
    } else if (self->uart_id == 4) {
        HAL_NVIC_DisableIRQ(UART4_IRQn);
        __HAL_RCC_UART4_FORCE_RESET();
        __HAL_RCC_UART4_RELEASE_RESET();
        __HAL_RCC_UART4_CLK_DISABLE();
    #endif
    #if defined(USART4)
    } else if (self->uart_id == 4) {
        __HAL_RCC_USART4_FORCE_RESET();
        __HAL_RCC_USART4_RELEASE_RESET();
        __HAL_RCC_USART4_CLK_DISABLE();
    #endif
    #if defined(UART5)
    } else if (self->uart_id == 5) {
        HAL_NVIC_DisableIRQ(UART5_IRQn);
        __HAL_RCC_UART5_FORCE_RESET();
        __HAL_RCC_UART5_RELEASE_RESET();
        __HAL_RCC_UART5_CLK_DISABLE();
    #endif
    #if defined(USART5)
    } else if (self->uart_id == 5) {
        __HAL_RCC_USART5_FORCE_RESET();
        __HAL_RCC_USART5_RELEASE_RESET();
        __HAL_RCC_USART5_CLK_DISABLE();
    #endif
    #if defined(UART6)
    } else if (self->uart_id == 6) {
        HAL_NVIC_DisableIRQ(USART6_IRQn);
        __HAL_RCC_USART6_FORCE_RESET();
        __HAL_RCC_USART6_RELEASE_RESET();
        __HAL_RCC_USART6_CLK_DISABLE();
    #endif
    #if defined(UART7)
    } else if (self->uart_id == 7) {
        HAL_NVIC_DisableIRQ(UART7_IRQn);
        __HAL_RCC_UART7_FORCE_RESET();
        __HAL_RCC_UART7_RELEASE_RESET();
        __HAL_RCC_UART7_CLK_DISABLE();
    #endif
    #if defined(USART7)
    } else if (self->uart_id == 7) {
        __HAL_RCC_USART7_FORCE_RESET();
        __HAL_RCC_USART7_RELEASE_RESET();
        __HAL_RCC_USART7_CLK_DISABLE();
    #endif
    #if defined(UART8)
    } else if (self->uart_id == 8) {
        HAL_NVIC_DisableIRQ(UART8_IRQn);
        __HAL_RCC_UART8_FORCE_RESET();
        __HAL_RCC_UART8_RELEASE_RESET();
        __HAL_RCC_UART8_CLK_DISABLE();
    #endif
    #if defined(USART8)
    } else if (self->uart_id == 8) {
        __HAL_RCC_USART8_FORCE_RESET();
        __HAL_RCC_USART8_RELEASE_RESET();
        __HAL_RCC_USART8_CLK_DISABLE();
    #endif
    #if defined(UART9)
    } else if (self->uart_id == 9) {
        HAL_NVIC_DisableIRQ(UART9_IRQn);
        __HAL_RCC_UART9_FORCE_RESET();
        __HAL_RCC_UART9_RELEASE_RESET();
        __HAL_RCC_UART9_CLK_DISABLE();
    #endif
    #if defined(UART10)
    } else if (self->uart_id == 10) {
        HAL_NVIC_DisableIRQ(UART10_IRQn);
        __HAL_RCC_UART10_FORCE_RESET();
        __HAL_RCC_UART10_RELEASE_RESET();
        __HAL_RCC_UART10_CLK_DISABLE();
    #endif
    #if defined(USART10)
    } else if (self->uart_id == 10) {
        HAL_NVIC_DisableIRQ(USART10_IRQn);
        __HAL_RCC_USART10_FORCE_RESET();
        __HAL_RCC_USART10_RELEASE_RESET();
        __HAL_RCC_USART10_CLK_DISABLE();
    #endif
    #if defined(LPUART1)
    } else if (self->uart_id == PYB_LPUART_1) {
        #if defined(STM32G0)
        HAL_NVIC_DisableIRQ(USART3_4_5_6_LPUART1_IRQn);
        #else
        HAL_NVIC_DisableIRQ(LPUART1_IRQn);
        #endif
        __HAL_RCC_LPUART1_FORCE_RESET();
        __HAL_RCC_LPUART1_RELEASE_RESET();
        __HAL_RCC_LPUART1_CLK_DISABLE();
    #endif
    #if defined(LPUART2)
    } else if (self->uart_id == PYB_LPUART_2) {
        #if defined(STM32G0)
        HAL_NVIC_DisableIRQ(USART2_LPUART2_IRQn);
        #else
        HAL_NVIC_DisableIRQ(LPUART2_IRQn);
        #endif
        __HAL_RCC_LPUART2_FORCE_RESET();
        __HAL_RCC_LPUART2_RELEASE_RESET();
        __HAL_RCC_LPUART2_CLK_DISABLE();
    #endif
    }
}

void uart_attach_to_repl(machine_uart_obj_t *self, bool attached) {
    self->attached_to_repl = attached;
}

uint32_t uart_get_source_freq(machine_uart_obj_t *self) {
    uint32_t uart_clk = 0;

    #if defined(STM32F0) || defined(STM32G0)
    uart_clk = HAL_RCC_GetPCLK1Freq();
    #elif defined(STM32F7)
    switch ((RCC->DCKCFGR2 >> ((self->uart_id - 1) * 2)) & 3) {
        case 0:
            if (self->uart_id == 1 || self->uart_id == 6) {
                uart_clk = HAL_RCC_GetPCLK2Freq();
            } else {
                uart_clk = HAL_RCC_GetPCLK1Freq();
            }
            break;
        case 1:
            uart_clk = HAL_RCC_GetSysClockFreq();
            break;
        case 2:
            uart_clk = HSI_VALUE;
            break;
        case 3:
            uart_clk = LSE_VALUE;
            break;
    }

    #elif defined(STM32H5) || defined(STM32H7)

    uint32_t csel;
    unsigned int bus_pclk;

    #if defined(STM32H5)
    if (1 <= self->uart_id && self->uart_id <= 10) {
        csel = RCC->CCIPR1 >> ((self->uart_id - 1) * 3);
    } else {
        csel = RCC->CCIPR2 >> ((self->uart_id - 11) * 3);
    }
    bus_pclk = self->uart_id == 1 ? 2 : 1;
    #elif defined(STM32H7A3xx) || defined(STM32H7A3xxQ) || defined(STM32H7B3xx) || defined(STM32H7B3xxQ)
    if (self->uart_id == 1 || self->uart_id == 6 || self->uart_id == 9 || self->uart_id == 10) {
        csel = RCC->CDCCIP2R >> 3;
        bus_pclk = 2;
    } else {
        csel = RCC->CDCCIP2R;
        bus_pclk = 1;
    }
    #else
    if (self->uart_id == 1 || self->uart_id == 6) {
        csel = RCC->D2CCIP2R >> 3;
        bus_pclk = 2;
    } else {
        csel = RCC->D2CCIP2R;
        bus_pclk = 1;
    }
    #endif

    switch (csel & 7) {
        case 0:
            if (bus_pclk == 1) {
                uart_clk = HAL_RCC_GetPCLK1Freq();
            } else {
                uart_clk = HAL_RCC_GetPCLK2Freq();
            }
            break;
        case 1: {
            LL_PLL_ClocksTypeDef PLL_Clocks;
            LL_RCC_GetPLL2ClockFreq(&PLL_Clocks);
            uart_clk = PLL_Clocks.PLL_Q_Frequency;
            break;
        }
        case 2: {
            LL_PLL_ClocksTypeDef PLL_Clocks;
            LL_RCC_GetPLL3ClockFreq(&PLL_Clocks);
            uart_clk = PLL_Clocks.PLL_Q_Frequency;
            break;
        }
        case 3:
            uart_clk = HSI_VALUE;
            break;
        case 4:
            uart_clk = CSI_VALUE;
            break;
        case 5:
            uart_clk = LSE_VALUE;
            break;
        default:
            break;
    }

    #elif defined(STM32N6)

    static const uint16_t is_usart = 1 << 10 | 1 << 6 | 1 << 3 | 1 << 2 | 1 << 1;
    static const uint32_t clksource[] = {
        LL_RCC_USART1_CLKSOURCE,
        LL_RCC_USART2_CLKSOURCE,
        LL_RCC_USART3_CLKSOURCE,
        LL_RCC_UART4_CLKSOURCE,
        LL_RCC_UART5_CLKSOURCE,
        LL_RCC_USART6_CLKSOURCE,
        LL_RCC_UART7_CLKSOURCE,
        LL_RCC_UART8_CLKSOURCE,
        LL_RCC_UART9_CLKSOURCE,
        LL_RCC_USART10_CLKSOURCE,
    };

    if (is_usart & (1 << self->uart_id)) {
        uart_clk = LL_RCC_GetUSARTClockFreq(clksource[self->uart_id - 1]);
    } else {
        uart_clk = LL_RCC_GetUARTClockFreq(clksource[self->uart_id - 1]);
    }

    #else
    if (self->uart_id == 1
        #if defined(USART6)
        || self->uart_id == 6
        #endif
        #if defined(UART9)
        || self->uart_id == 9
        #endif
        #if defined(UART10) || defined(USART10)
        || self->uart_id == 10
        #endif
        ) {
        uart_clk = HAL_RCC_GetPCLK2Freq();
    } else {
        uart_clk = HAL_RCC_GetPCLK1Freq();
    }
    #endif

    return uart_clk;
}

uint32_t uart_get_baudrate(machine_uart_obj_t *self) {
    #if defined(LPUART1)
    if (self->uart_id == PYB_LPUART_1) {
        return LL_LPUART_GetBaudRate(self->uartx, uart_get_source_freq(self)
            #if defined(STM32G0) || defined(STM32G4) || defined(STM32H5) || defined(STM32H7) || defined(STM32N6) || defined(STM32WB) || defined(STM32WL)
            , self->uartx->PRESC
            #endif
            );
    }
    #endif
    return LL_USART_GetBaudRate(self->uartx, uart_get_source_freq(self),
        #if defined(STM32G0) || defined(STM32G4) || defined(STM32H5) || defined(STM32H7) || defined(STM32N6) || defined(STM32WB) || defined(STM32WL)
        self->uartx->PRESC,
        #endif
        LL_USART_OVERSAMPLING_16);
}

void uart_set_baudrate(machine_uart_obj_t *self, uint32_t baudrate) {
    #if defined(LPUART1)
    if (self->uart_id == PYB_LPUART_1) {
        LL_LPUART_SetBaudRate(self->uartx, uart_get_source_freq(self),
            #if defined(STM32G0) || defined(STM32G4) || defined(STM32H5) || defined(STM32H7) || defined(STM32N6) || defined(STM32WB) || defined(STM32WL)
            LL_LPUART_PRESCALER_DIV1,
            #endif
            baudrate);
        return;
    }
    #endif
    LL_USART_SetBaudRate(self->uartx, uart_get_source_freq(self),
        #if defined(STM32G0) || defined(STM32G4) || defined(STM32H5) || defined(STM32H7) || defined(STM32N6) || defined(STM32WB) || defined(STM32WL)
        LL_USART_PRESCALER_DIV1,
        #endif
        LL_USART_OVERSAMPLING_16, baudrate);
}

mp_uint_t uart_rx_any(machine_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 UART_RXNE_IS_SET(self->uartx) != 0;
    }
}

// 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.
bool uart_rx_wait(machine_uart_obj_t *self, uint32_t timeout) {
    uint32_t start = HAL_GetTick();
    for (;;) {
        if (self->read_buf_tail != self->read_buf_head || UART_RXNE_IS_SET(self->uartx)) {
            return true; // have at least 1 char ready for reading
        }
        if (HAL_GetTick() - start >= timeout) {
            return false; // timeout
        }
        MICROPY_EVENT_POLL_HOOK
    }
}

// assumes there is a character available
int uart_rx_char(machine_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 (UART_RXNE_IS_SET(self->uartx)) {
            // UART was stalled by flow ctrl: re-enable IRQ now we have room in buffer
            UART_RXNE_IT_EN(self->uartx);
        }
        return data;
    } else {
        // no buffering
        #if defined(STM32F0) || defined(STM32F7) || defined(STM32G0) || defined(STM32G4) || defined(STM32H5) || defined(STM32L0) || defined(STM32L4) || defined(STM32H7) || defined(STM32N6) || defined(STM32WB) || defined(STM32WL)
        int data = self->uartx->RDR & self->char_mask;
        self->uartx->ICR = USART_ICR_ORECF; // clear ORE if it was set
        return data;
        #else
        int data = self->uartx->DR & self->char_mask;
        // Re-enable any IRQs that were disabled in uart_irq_handler because SR couldn't
        // be cleared there (clearing SR in uart_irq_handler required reading DR which
        // may have lost a character).
        if (self->mp_irq_trigger & UART_FLAG_RXNE) {
            self->uartx->CR1 |= USART_CR1_RXNEIE;
        }
        if (self->mp_irq_trigger & UART_FLAG_IDLE) {
            self->uartx->CR1 |= USART_CR1_IDLEIE;
        }
        return data;
        #endif
    }
}

// Waits at most timeout milliseconds for TX register to become empty.
// Returns true if can write, false if can't.
bool uart_tx_wait(machine_uart_obj_t *self, uint32_t timeout) {
    uint32_t start = HAL_GetTick();
    for (;;) {
        if (uart_tx_avail(self)) {
            return true; // tx register is empty
        }
        if (HAL_GetTick() - start >= timeout) {
            return false; // timeout
        }
        MICROPY_EVENT_POLL_HOOK
    }
}

// Waits at most timeout milliseconds for UART flag to be set.
// Returns true if flag is/was set, false on timeout.
static bool uart_wait_flag_set(machine_uart_obj_t *self, uint32_t flag, uint32_t timeout) {
    // Note: we don't use WFI to idle in this loop because UART tx doesn't generate
    // an interrupt and the flag can be set quickly if the baudrate is large.
    uint32_t start = HAL_GetTick();
    for (;;) {
        #if defined(STM32F4) || defined(STM32L1)
        if (self->uartx->SR & flag) {
            return true;
        }
        #else
        if (self->uartx->ISR & flag) {
            return true;
        }
        #endif
        if (timeout == 0 || HAL_GetTick() - start >= timeout) {
            return false; // timeout
        }
    }
}

// src - a pointer to the data to send (16-bit aligned for 9-bit chars)
// num_chars - number of characters to send (9-bit chars count for 2 bytes from src)
// *errcode - returns 0 for success, MP_Exxx on error
// returns the number of characters sent (valid even if there was an error)
size_t uart_tx_data(machine_uart_obj_t *self, const void *src_in, size_t num_chars, int *errcode) {
    if (num_chars == 0) {
        *errcode = 0;
        return 0;
    }

    uint32_t timeout;
    #if defined(STM32G4)
    // With using UART FIFO, the timeout should be long enough that FIFO becomes empty.
    // Since previous data transfer may be ongoing, the timeout must be multiplied
    // timeout_char by FIFO size + 1.
    // STM32G4 has 8 words FIFO.
    timeout = (8 + 1) * self->timeout_char;
    #elif defined(STM32H7)
    // STM32H7 has 16 words FIFO.
    timeout = (16 + 1) * self->timeout_char;
    #else
    // 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.
    timeout = 2 * self->timeout_char;
    #endif

    const uint8_t *src = (const uint8_t *)src_in;
    size_t num_tx = 0;
    USART_TypeDef *uart = self->uartx;

    while (num_tx < num_chars) {
        if (!uart_wait_flag_set(self, UART_FLAG_TXE, timeout)) {
            *errcode = MP_ETIMEDOUT;
            return num_tx;
        }
        uint32_t data;
        if (self->char_width == CHAR_WIDTH_9BIT) {
            data = *((uint16_t *)src) & 0x1ff;
            src += 2;
        } else {
            data = *src++;
        }
        #if defined(STM32F4) || defined(STM32L1)
        uart->DR = data;
        #else
        uart->TDR = data;
        #endif
        ++num_tx;
    }

    // wait for the UART frame to complete
    if (!uart_wait_flag_set(self, UART_FLAG_TC, timeout)) {
        *errcode = MP_ETIMEDOUT;
        return num_tx;
    }

    *errcode = 0;
    return num_tx;
}

void uart_tx_strn(machine_uart_obj_t *uart_obj, const char *str, uint len) {
    int errcode;
    uart_tx_data(uart_obj, str, len, &errcode);
}

// This IRQ handler is set up to handle RXNE, IDLE and ORE interrupts only.
// Notes:
// - ORE (overrun error) is tied to the RXNE IRQ line.
// - On STM32F4 the IRQ flags are cleared by reading SR then DR.
void uart_irq_handler(mp_uint_t uart_id) {
    // get the uart object
    machine_uart_obj_t *self = MP_STATE_PORT(machine_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;
    }

    // Capture IRQ status flags.
    #if defined(STM32F4) || defined(STM32L1)
    self->mp_irq_flags = self->uartx->SR;
    bool rxne_is_set = self->mp_irq_flags & USART_SR_RXNE;
    bool did_clear_sr = false;
    #else
    self->mp_irq_flags = self->uartx->ISR;
    bool rxne_is_set = self->mp_irq_flags & USART_ISR_RXNE;
    #endif

    // Process RXNE flag, either read the character or disable the interrupt.
    if (rxne_is_set) {
        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(STM32F0) || defined(STM32F7) || defined(STM32G0) || defined(STM32G4) || defined(STM32H5) || defined(STM32H7) || defined(STM32L0) || defined(STM32L4) || defined(STM32N6) || defined(STM32WB) || defined(STM32WL)
                int data = self->uartx->RDR; // clears UART_FLAG_RXNE
                #else
                self->mp_irq_flags = self->uartx->SR; // resample to get any new flags since next read of DR will clear SR
                int data = self->uartx->DR; // clears UART_FLAG_RXNE
                did_clear_sr = true;
                #endif
                data &= self->char_mask;
                if (self->attached_to_repl && data == mp_interrupt_char) {
                    // Handle interrupt coming in on a UART REPL
                    mp_sched_keyboard_interrupt();
                } else {
                    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
                UART_RXNE_IT_DIS(self->uartx);
            }
        } else {
            // No buffering, disable interrupt.
            UART_RXNE_IT_DIS(self->uartx);
        }
    }

    // Clear other interrupt flags that can trigger this IRQ handler.
    #if defined(STM32F4) || defined(STM32L1)
    if (did_clear_sr) {
        // SR was cleared above.  Re-enable IDLE if it should be enabled.
        if (self->mp_irq_trigger & UART_FLAG_IDLE) {
            self->uartx->CR1 |= USART_CR1_IDLEIE;
        }
    } else {
        // On STM32F4 the only way to clear flags is to read SR then DR, but that may
        // lead to a loss of data in DR.  So instead the IRQs are disabled.
        if (self->mp_irq_flags & USART_SR_IDLE) {
            self->uartx->CR1 &= ~USART_CR1_IDLEIE;
        }
        if (self->mp_irq_flags & USART_SR_ORE) {
            // ORE is tied to RXNE so that must be disabled.
            self->uartx->CR1 &= ~USART_CR1_RXNEIE;
        }
    }
    if (self->suppress_idle_irq) {
        self->mp_irq_flags &= ~USART_SR_IDLE;
    }
    #else
    self->uartx->ICR = self->mp_irq_flags & (USART_ICR_IDLECF | USART_ICR_ORECF);
    #endif

    // Check the flags to see if the user handler should be called
    if (self->mp_irq_trigger & self->mp_irq_flags) {
        mp_irq_handler(self->mp_irq_obj);
    }

    #if defined(STM32F4) || defined(STM32L1)
    if (did_clear_sr) {
        self->suppress_idle_irq = false;
    } else {
        self->suppress_idle_irq = true;
    }
    #endif
}

static mp_uint_t uart_irq_trigger(mp_obj_t self_in, mp_uint_t new_trigger) {
    machine_uart_obj_t *self = MP_OBJ_TO_PTR(self_in);
    uart_irq_config(self, false);
    self->mp_irq_trigger = new_trigger;
    uart_irq_config(self, true);
    return 0;
}

static mp_uint_t uart_irq_info(mp_obj_t self_in, mp_uint_t info_type) {
    machine_uart_obj_t *self = MP_OBJ_TO_PTR(self_in);
    if (info_type == MP_IRQ_INFO_FLAGS) {
        return self->mp_irq_flags;
    } else if (info_type == MP_IRQ_INFO_TRIGGERS) {
        return self->mp_irq_trigger;
    }
    return 0;
}

const mp_irq_methods_t uart_irq_methods = {
    .trigger = uart_irq_trigger,
    .info = uart_irq_info,
};

MP_REGISTER_ROOT_POINTER(struct _machine_uart_obj_t *machine_uart_obj_all[MICROPY_HW_MAX_UART + MICROPY_HW_MAX_LPUART]);