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i2c.c

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  • i2c.c 35.52 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 "py/nlr.h"
    #include "py/runtime.h"
    #include "py/mphal.h"
    #include "irq.h"
    #include "pin.h"
    #include "genhdr/pins.h"
    #include "bufhelper.h"
    #include "dma.h"
    #include "i2c.h"
    
    /// \moduleref pyb
    /// \class I2C - a two-wire serial protocol
    ///
    /// I2C is a two-wire protocol for communicating between devices.  At the physical
    /// level it consists of 2 wires: SCL and SDA, the clock and data lines respectively.
    ///
    /// I2C objects are created attached to a specific bus.  They can be initialised
    /// when created, or initialised later on:
    ///
    ///     from pyb import I2C
    ///
    ///     i2c = I2C(1)                         # create on bus 1
    ///     i2c = I2C(1, I2C.MASTER)             # create and init as a master
    ///     i2c.init(I2C.MASTER, baudrate=20000) # init as a master
    ///     i2c.init(I2C.SLAVE, addr=0x42)       # init as a slave with given address
    ///     i2c.deinit()                         # turn off the peripheral
    ///
    /// Printing the i2c object gives you information about its configuration.
    ///
    /// Basic methods for slave are send and recv:
    ///
    ///     i2c.send('abc')      # send 3 bytes
    ///     i2c.send(0x42)       # send a single byte, given by the number
    ///     data = i2c.recv(3)   # receive 3 bytes
    ///
    /// To receive inplace, first create a bytearray:
    ///
    ///     data = bytearray(3)  # create a buffer
    ///     i2c.recv(data)       # receive 3 bytes, writing them into data
    ///
    /// You can specify a timeout (in ms):
    ///
    ///     i2c.send(b'123', timeout=2000)   # timout after 2 seconds
    ///
    /// A master must specify the recipient's address:
    ///
    ///     i2c.init(I2C.MASTER)
    ///     i2c.send('123', 0x42)        # send 3 bytes to slave with address 0x42
    ///     i2c.send(b'456', addr=0x42)  # keyword for address
    ///
    /// Master also has other methods:
    ///
    ///     i2c.is_ready(0x42)           # check if slave 0x42 is ready
    ///     i2c.scan()                   # scan for slaves on the bus, returning
    ///                                  #   a list of valid addresses
    ///     i2c.mem_read(3, 0x42, 2)     # read 3 bytes from memory of slave 0x42,
    ///                                  #   starting at address 2 in the slave
    ///     i2c.mem_write('abc', 0x42, 2, timeout=1000)
    #define PYB_I2C_MASTER (0)
    #define PYB_I2C_SLAVE  (1)
    
    #if defined(MICROPY_HW_I2C1_SCL)
    I2C_HandleTypeDef I2CHandle1 = {.Instance = NULL};
    #endif
    #if defined(MICROPY_HW_I2C2_SCL)
    I2C_HandleTypeDef I2CHandle2 = {.Instance = NULL};
    #endif
    #if defined(MICROPY_HW_I2C3_SCL)
    I2C_HandleTypeDef I2CHandle3 = {.Instance = NULL};
    #endif
    #if defined(MICROPY_HW_I2C4_SCL)
    I2C_HandleTypeDef I2CHandle4 = {.Instance = NULL};
    #endif
    
    STATIC bool pyb_i2c_use_dma[4];
    
    const pyb_i2c_obj_t pyb_i2c_obj[] = {
        #if defined(MICROPY_HW_I2C1_SCL)
        {{&pyb_i2c_type}, &I2CHandle1, &dma_I2C_1_TX, &dma_I2C_1_RX, &pyb_i2c_use_dma[0]},
        #else
        {{&pyb_i2c_type}, NULL, NULL, NULL, NULL},
        #endif
        #if defined(MICROPY_HW_I2C2_SCL)
        {{&pyb_i2c_type}, &I2CHandle2, &dma_I2C_2_TX, &dma_I2C_2_RX, &pyb_i2c_use_dma[1]},
        #else
        {{&pyb_i2c_type}, NULL, NULL, NULL, NULL},
        #endif
        #if defined(MICROPY_HW_I2C3_SCL)
        {{&pyb_i2c_type}, &I2CHandle3, &dma_I2C_3_TX, &dma_I2C_3_RX, &pyb_i2c_use_dma[2]},
        #else
        {{&pyb_i2c_type}, NULL, NULL, NULL, NULL},
        #endif
        #if defined(MICROPY_HW_I2C4_SCL)
        {{&pyb_i2c_type}, &I2CHandle4, &dma_I2C_4_TX, &dma_I2C_4_RX, &pyb_i2c_use_dma[3]},
        #else
        {{&pyb_i2c_type}, NULL, NULL, NULL, NULL},
        #endif
    };
    
    #if defined(MCU_SERIES_F7) || defined(MCU_SERIES_L4)
    
    // The STM32F0, F3, F7 and L4 use a TIMINGR register rather than ClockSpeed and
    // DutyCycle.
    
    #if defined(STM32F746xx)
    
    // The value 0x40912732 was obtained from the DISCOVERY_I2Cx_TIMING constant
    // defined in the STM32F7Cube file Drivers/BSP/STM32F746G-Discovery/stm32f7456g_discovery.h
    #define MICROPY_HW_I2C_BAUDRATE_TIMING {{100000, 0x40912732}}
    #define MICROPY_HW_I2C_BAUDRATE_DEFAULT (100000)
    #define MICROPY_HW_I2C_BAUDRATE_MAX (100000)
    
    #elif defined(STM32F767xx) || defined(STM32F769xx)
    
    // These timing values are for f_I2CCLK=54MHz and are only approximate
    #define MICROPY_HW_I2C_BAUDRATE_TIMING { \
            {100000, 0xb0420f13}, \
            {400000, 0x70330309}, \
            {1000000, 0x50100103}, \
        }
    #define MICROPY_HW_I2C_BAUDRATE_DEFAULT (400000)
    #define MICROPY_HW_I2C_BAUDRATE_MAX (1000000)
    
    #elif defined(MCU_SERIES_L4)
    
    // The value 0x90112626 was obtained from the DISCOVERY_I2C1_TIMING constant
    // defined in the STM32L4Cube file Drivers/BSP/STM32L476G-Discovery/stm32l476g_discovery.h
    #define MICROPY_HW_I2C_BAUDRATE_TIMING {{100000, 0x90112626}}
    #define MICROPY_HW_I2C_BAUDRATE_DEFAULT (100000)
    #define MICROPY_HW_I2C_BAUDRATE_MAX (100000)
    
    #else
    #error "no I2C timings for this MCU"
    #endif
    
    STATIC const struct {
        uint32_t    baudrate;
        uint32_t    timing;
    } pyb_i2c_baudrate_timing[] = MICROPY_HW_I2C_BAUDRATE_TIMING;
    
    #define NUM_BAUDRATE_TIMINGS MP_ARRAY_SIZE(pyb_i2c_baudrate_timing)
    
    STATIC void i2c_set_baudrate(I2C_InitTypeDef *init, uint32_t baudrate) {
        for (int i = 0; i < NUM_BAUDRATE_TIMINGS; i++) {
            if (pyb_i2c_baudrate_timing[i].baudrate == baudrate) {
                init->Timing = pyb_i2c_baudrate_timing[i].timing;
                return;
            }
        }
        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError,
                                                "Unsupported I2C baudrate: %lu", baudrate));
    }
    
    uint32_t i2c_get_baudrate(I2C_InitTypeDef *init) {
        for (int i = 0; i < NUM_BAUDRATE_TIMINGS; i++) {
            if (pyb_i2c_baudrate_timing[i].timing == init->Timing) {
                return pyb_i2c_baudrate_timing[i].baudrate;
            }
        }
        return 0;
    }
    
    #else
    
    #define MICROPY_HW_I2C_BAUDRATE_DEFAULT (400000)
    #define MICROPY_HW_I2C_BAUDRATE_MAX (400000)
    
    STATIC void i2c_set_baudrate(I2C_InitTypeDef *init, uint32_t baudrate) {
        init->ClockSpeed = baudrate;
        init->DutyCycle = I2C_DUTYCYCLE_16_9;
    }
    
    uint32_t i2c_get_baudrate(I2C_InitTypeDef *init) {
        return init->ClockSpeed;
    }
    
    #endif
    
    void i2c_init0(void) {
        // reset the I2C1 handles
        #if defined(MICROPY_HW_I2C1_SCL)
        memset(&I2CHandle1, 0, sizeof(I2C_HandleTypeDef));
        I2CHandle1.Instance = I2C1;
        #endif
        #if defined(MICROPY_HW_I2C2_SCL)
        memset(&I2CHandle2, 0, sizeof(I2C_HandleTypeDef));
        I2CHandle2.Instance = I2C2;
        #endif
        #if defined(MICROPY_HW_I2C3_SCL)
        memset(&I2CHandle3, 0, sizeof(I2C_HandleTypeDef));
        I2CHandle3.Instance = I2C3;
        #endif
        #if defined(MICROPY_HW_I2C4_SCL)
        memset(&I2CHandle4, 0, sizeof(I2C_HandleTypeDef));
        I2CHandle3.Instance = I2C4;
        #endif
    }
    
    void i2c_init(I2C_HandleTypeDef *i2c) {
        int i2c_unit;
        const pin_obj_t *scl_pin;
        const pin_obj_t *sda_pin;
    
        if (0) {
        #if defined(MICROPY_HW_I2C1_SCL)
        } else if (i2c == &I2CHandle1) {
            i2c_unit = 1;
            scl_pin = &MICROPY_HW_I2C1_SCL;
            sda_pin = &MICROPY_HW_I2C1_SDA;
            __I2C1_CLK_ENABLE();
        #endif
        #if defined(MICROPY_HW_I2C2_SCL)
        } else if (i2c == &I2CHandle2) {
            i2c_unit = 2;
            scl_pin = &MICROPY_HW_I2C2_SCL;
            sda_pin = &MICROPY_HW_I2C2_SDA;
            __I2C2_CLK_ENABLE();
        #endif
        #if defined(MICROPY_HW_I2C3_SCL)
        } else if (i2c == &I2CHandle3) {
            i2c_unit = 3;
            scl_pin = &MICROPY_HW_I2C3_SCL;
            sda_pin = &MICROPY_HW_I2C3_SDA;
            __I2C3_CLK_ENABLE();
        #endif
        #if defined(MICROPY_HW_I2C4_SCL)
        } else if (i2c == &I2CHandle4) {
            i2c_unit = 4;
            scl_pin = &MICROPY_HW_I2C4_SCL;
            sda_pin = &MICROPY_HW_I2C4_SDA;
            __I2C3_CLK_ENABLE();
        #endif
        } else {
            // I2C does not exist for this board (shouldn't get here, should be checked by caller)
            return;
        }
    
        // init the GPIO lines
        uint32_t mode = MP_HAL_PIN_MODE_ALT_OPEN_DRAIN;
        uint32_t pull = MP_HAL_PIN_PULL_NONE; // have external pull-up resistors on both lines
        mp_hal_pin_config_alt(scl_pin, mode, pull, AF_FN_I2C, i2c_unit);
        mp_hal_pin_config_alt(sda_pin, mode, pull, AF_FN_I2C, i2c_unit);
    
        // init the I2C device
        if (HAL_I2C_Init(i2c) != HAL_OK) {
            // init error
            // TODO should raise an exception, but this function is not necessarily going to be
            // called via Python, so may not be properly wrapped in an NLR handler
            printf("OSError: HAL_I2C_Init failed\n");
            return;
        }
    
        // invalidate the DMA channels so they are initialised on first use
        const pyb_i2c_obj_t *self = &pyb_i2c_obj[i2c_unit - 1];
        dma_invalidate_channel(self->tx_dma_descr);
        dma_invalidate_channel(self->rx_dma_descr);
        
        if (0) {
        #if defined(MICROPY_HW_I2C1_SCL)
        } else if (i2c->Instance == I2C1) {
            HAL_NVIC_EnableIRQ(I2C1_EV_IRQn);
            HAL_NVIC_EnableIRQ(I2C1_ER_IRQn);
        #endif
        #if defined(MICROPY_HW_I2C2_SCL)
        } else if (i2c->Instance == I2C2) {
            HAL_NVIC_EnableIRQ(I2C2_EV_IRQn);
            HAL_NVIC_EnableIRQ(I2C2_ER_IRQn);
        #endif
        #if defined(MICROPY_HW_I2C3_SCL)
        } else if (i2c->Instance == I2C3) {
            HAL_NVIC_EnableIRQ(I2C3_EV_IRQn);
            HAL_NVIC_EnableIRQ(I2C3_ER_IRQn);
        #endif
        #if defined(MICROPY_HW_I2C4_SCL)
        } else if (i2c->Instance == I2C4) {
            HAL_NVIC_EnableIRQ(I2C4_EV_IRQn);
            HAL_NVIC_EnableIRQ(I2C4_ER_IRQn);
        #endif
        }
    }
    
    void i2c_deinit(I2C_HandleTypeDef *i2c) {
        HAL_I2C_DeInit(i2c);
        if (0) {
        #if defined(MICROPY_HW_I2C1_SCL)
        } else if (i2c->Instance == I2C1) {
            __I2C1_FORCE_RESET();
            __I2C1_RELEASE_RESET();
            __I2C1_CLK_DISABLE();
            HAL_NVIC_DisableIRQ(I2C1_EV_IRQn);
            HAL_NVIC_DisableIRQ(I2C1_ER_IRQn);
        #endif
        #if defined(MICROPY_HW_I2C2_SCL)
        } else if (i2c->Instance == I2C2) {
            __I2C2_FORCE_RESET();
            __I2C2_RELEASE_RESET();
            __I2C2_CLK_DISABLE();
            HAL_NVIC_DisableIRQ(I2C2_EV_IRQn);
            HAL_NVIC_DisableIRQ(I2C2_ER_IRQn);
        #endif
        #if defined(MICROPY_HW_I2C3_SCL)
        } else if (i2c->Instance == I2C3) {
            __I2C3_FORCE_RESET();
            __I2C3_RELEASE_RESET();
            __I2C3_CLK_DISABLE();
            HAL_NVIC_DisableIRQ(I2C3_EV_IRQn);
            HAL_NVIC_DisableIRQ(I2C3_ER_IRQn);
        #endif
        #if defined(MICROPY_HW_I2C4_SCL)
        } else if (i2c->Instance == I2C4) {
            __HAL_RCC_I2C4_FORCE_RESET();
            __HAL_RCC_I2C4_RELEASE_RESET();
            __HAL_RCC_I2C4_CLK_DISABLE();
            HAL_NVIC_DisableIRQ(I2C4_EV_IRQn);
            HAL_NVIC_DisableIRQ(I2C4_ER_IRQn);
        #endif
        }
    }
    
    void i2c_init_freq(const pyb_i2c_obj_t *self, mp_int_t freq) {
        I2C_InitTypeDef *init = &self->i2c->Init;
    
        init->AddressingMode    = I2C_ADDRESSINGMODE_7BIT;
        init->DualAddressMode   = I2C_DUALADDRESS_DISABLED;
        init->GeneralCallMode   = I2C_GENERALCALL_DISABLED;
        init->NoStretchMode     = I2C_NOSTRETCH_DISABLE;
        init->OwnAddress1       = PYB_I2C_MASTER_ADDRESS;
        init->OwnAddress2       = 0; // unused
        if (freq != -1) {
            i2c_set_baudrate(init, MIN(freq, MICROPY_HW_I2C_BAUDRATE_MAX));
        }
    
        *self->use_dma = false;
    
        // init the I2C bus
        i2c_deinit(self->i2c);
        i2c_init(self->i2c);
    }
    
    STATIC void i2c_reset_after_error(I2C_HandleTypeDef *i2c) {
        // wait for bus-busy flag to be cleared, with a timeout
        for (int timeout = 50; timeout > 0; --timeout) {
            if (!__HAL_I2C_GET_FLAG(i2c, I2C_FLAG_BUSY)) {
                // stop bit was generated and bus is back to normal
                return;
            }
            mp_hal_delay_ms(1);
        }
        // bus was/is busy, need to reset the peripheral to get it to work again
        i2c_deinit(i2c);
        i2c_init(i2c);
    }
    
    void i2c_ev_irq_handler(mp_uint_t i2c_id) {
        I2C_HandleTypeDef *hi2c;
    
        switch (i2c_id) {
            #if defined(MICROPY_HW_I2C1_SCL)
            case 1:
                hi2c = &I2CHandle1;
                break;
            #endif
            #if defined(MICROPY_HW_I2C2_SCL)
            case 2:
                hi2c = &I2CHandle2;
                break;
            #endif
            #if defined(MICROPY_HW_I2C3_SCL)
            case 3:
                hi2c = &I2CHandle3;
                break;
            #endif
            #if defined(MICROPY_HW_I2C4_SCL)
            case 4:
                hi2c = &I2CHandle4;
                break;
            #endif
            default:
                return;
        }
    
        #if defined(MCU_SERIES_F4)
    
        if (hi2c->Instance->SR1 & I2C_FLAG_BTF && hi2c->State == HAL_I2C_STATE_BUSY_TX) {
            if (hi2c->XferCount != 0U) {
                hi2c->Instance->DR = *hi2c->pBuffPtr++;
                hi2c->XferCount--;
            } else {
                __HAL_I2C_DISABLE_IT(hi2c, I2C_IT_EVT | I2C_IT_BUF | I2C_IT_ERR);
                if (hi2c->XferOptions != I2C_FIRST_FRAME) {
                    hi2c->Instance->CR1 |= I2C_CR1_STOP;
                }
                hi2c->Mode = HAL_I2C_MODE_NONE;
                hi2c->State = HAL_I2C_STATE_READY;
            }
        }
    
        #else
    
        // if not an F4 MCU, use the HAL's IRQ handler
        HAL_I2C_EV_IRQHandler(hi2c);
    
        #endif
    }
    
    void i2c_er_irq_handler(mp_uint_t i2c_id) {
        I2C_HandleTypeDef *hi2c;
    
        switch (i2c_id) {
            #if defined(MICROPY_HW_I2C1_SCL)
            case 1:
                hi2c = &I2CHandle1;
                break;
            #endif
            #if defined(MICROPY_HW_I2C2_SCL)
            case 2:
                hi2c = &I2CHandle2;
                break;
            #endif
            #if defined(MICROPY_HW_I2C3_SCL)
            case 3:
                hi2c = &I2CHandle3;
                break;
            #endif
            #if defined(MICROPY_HW_I2C4_SCL)
            case 4:
                hi2c = &I2CHandle4;
                break;
            #endif
            default:
                return;
        }
    
        #if defined(MCU_SERIES_F4)
    
        uint32_t sr1 = hi2c->Instance->SR1;
    
        // I2C Bus error
        if (sr1 & I2C_FLAG_BERR) {
            hi2c->ErrorCode |= HAL_I2C_ERROR_BERR;
            __HAL_I2C_CLEAR_FLAG(hi2c, I2C_FLAG_BERR);
        }
    
        // I2C Arbitration Loss error
        if (sr1 & I2C_FLAG_ARLO) {
            hi2c->ErrorCode |= HAL_I2C_ERROR_ARLO;
            __HAL_I2C_CLEAR_FLAG(hi2c, I2C_FLAG_ARLO);
        }
    
        // I2C Acknowledge failure
        if (sr1 & I2C_FLAG_AF) {
            hi2c->ErrorCode |= HAL_I2C_ERROR_AF;
            SET_BIT(hi2c->Instance->CR1,I2C_CR1_STOP);
            __HAL_I2C_CLEAR_FLAG(hi2c, I2C_FLAG_AF);
        }
    
        // I2C Over-Run/Under-Run
        if (sr1 & I2C_FLAG_OVR) {
            hi2c->ErrorCode |= HAL_I2C_ERROR_OVR;
            __HAL_I2C_CLEAR_FLAG(hi2c, I2C_FLAG_OVR);
        }
    
        #else
    
        // if not an F4 MCU, use the HAL's IRQ handler
        HAL_I2C_ER_IRQHandler(hi2c);
    
        #endif
    }
    
    STATIC HAL_StatusTypeDef i2c_wait_dma_finished(I2C_HandleTypeDef *i2c, uint32_t timeout) {
        // Note: we can't use WFI to idle in this loop because the DMA completion
        // interrupt may occur before the WFI.  Hence we miss it and have to wait
        // until the next sys-tick (up to 1ms).
        uint32_t start = HAL_GetTick();
        while (HAL_I2C_GetState(i2c) != HAL_I2C_STATE_READY) {
            if (HAL_GetTick() - start >= timeout) {
                return HAL_TIMEOUT;
            }
        }
        return HAL_OK;
    }
    
    /******************************************************************************/
    /* Micro Python bindings                                                      */
    
    STATIC inline bool in_master_mode(pyb_i2c_obj_t *self) { return self->i2c->Init.OwnAddress1 == PYB_I2C_MASTER_ADDRESS; }
    
    STATIC void pyb_i2c_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
        pyb_i2c_obj_t *self = self_in;
    
        uint i2c_num = 0;
        if (0) { }
        #if defined(MICROPY_HW_I2C1_SCL)
        else if (self->i2c->Instance == I2C1) { i2c_num = 1; }
        #endif
        #if defined(MICROPY_HW_I2C2_SCL)
        else if (self->i2c->Instance == I2C2) { i2c_num = 2; }
        #endif
        #if defined(MICROPY_HW_I2C3_SCL)
        else if (self->i2c->Instance == I2C3) { i2c_num = 3; }
        #endif
        #if defined(MICROPY_HW_I2C4_SCL)
        else if (self->i2c->Instance == I2C4) { i2c_num = 4; }
        #endif
    
        if (self->i2c->State == HAL_I2C_STATE_RESET) {
            mp_printf(print, "I2C(%u)", i2c_num);
        } else {
            if (in_master_mode(self)) {
                mp_printf(print, "I2C(%u, I2C.MASTER, baudrate=%u)", i2c_num, i2c_get_baudrate(&self->i2c->Init));
            } else {
                mp_printf(print, "I2C(%u, I2C.SLAVE, addr=0x%02x)", i2c_num, (self->i2c->Instance->OAR1 >> 1) & 0x7f);
            }
        }
    }
    
    /// \method init(mode, *, addr=0x12, baudrate=400000, gencall=False)
    ///
    /// Initialise the I2C bus with the given parameters:
    ///
    ///   - `mode` must be either `I2C.MASTER` or `I2C.SLAVE`
    ///   - `addr` is the 7-bit address (only sensible for a slave)
    ///   - `baudrate` is the SCL clock rate (only sensible for a master)
    ///   - `gencall` is whether to support general call mode
    STATIC mp_obj_t pyb_i2c_init_helper(const pyb_i2c_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_mode,     MP_ARG_INT, {.u_int = PYB_I2C_MASTER} },
            { MP_QSTR_addr,     MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0x12} },
            { MP_QSTR_baudrate, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = MICROPY_HW_I2C_BAUDRATE_DEFAULT} },
            { MP_QSTR_gencall,  MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false} },
            { MP_QSTR_dma,      MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false} },
        };
    
        // parse args
        mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
        mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
    
        // set the I2C configuration values
        I2C_InitTypeDef *init = &self->i2c->Init;
    
        if (args[0].u_int == PYB_I2C_MASTER) {
            // use a special address to indicate we are a master
            init->OwnAddress1 = PYB_I2C_MASTER_ADDRESS;
        } else {
            init->OwnAddress1 = (args[1].u_int << 1) & 0xfe;
        }
    
        i2c_set_baudrate(init, MIN(args[2].u_int, MICROPY_HW_I2C_BAUDRATE_MAX));
        init->AddressingMode  = I2C_ADDRESSINGMODE_7BIT;
        init->DualAddressMode = I2C_DUALADDRESS_DISABLED;
        init->GeneralCallMode = args[3].u_bool ? I2C_GENERALCALL_ENABLED : I2C_GENERALCALL_DISABLED;
        init->OwnAddress2     = 0; // unused
        init->NoStretchMode   = I2C_NOSTRETCH_DISABLE;
    
        *self->use_dma = args[4].u_bool;
    
        // init the I2C bus
        i2c_deinit(self->i2c);
        i2c_init(self->i2c);
    
        return mp_const_none;
    }
    
    /// \classmethod \constructor(bus, ...)
    ///
    /// Construct an I2C object on the given bus.  `bus` can be 1 or 2.
    /// With no additional parameters, the I2C 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 I2C busses are:
    ///
    ///   - `I2C(1)` is on the X position: `(SCL, SDA) = (X9, X10) = (PB6, PB7)`
    ///   - `I2C(2)` is on the Y position: `(SCL, SDA) = (Y9, Y10) = (PB10, PB11)`
    STATIC mp_obj_t pyb_i2c_make_new(const mp_obj_type_t *type, size_t n_args, size_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 i2c bus
        int i2c_id = 0;
        if (MP_OBJ_IS_STR(args[0])) {
            const char *port = mp_obj_str_get_str(args[0]);
            if (0) {
            #ifdef MICROPY_HW_I2C1_NAME
            } else if (strcmp(port, MICROPY_HW_I2C1_NAME) == 0) {
                i2c_id = 1;
            #endif
            #ifdef MICROPY_HW_I2C2_NAME
            } else if (strcmp(port, MICROPY_HW_I2C2_NAME) == 0) {
                i2c_id = 2;
            #endif
            #ifdef MICROPY_HW_I2C3_NAME
            } else if (strcmp(port, MICROPY_HW_I2C3_NAME) == 0) {
                i2c_id = 3;
            #endif
            } else {
                nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError,
                    "I2C(%s) does not exist", port));
            }
        } else {
            i2c_id = mp_obj_get_int(args[0]);
            if (i2c_id < 1 || i2c_id > MP_ARRAY_SIZE(pyb_i2c_obj)
                || pyb_i2c_obj[i2c_id - 1].i2c == NULL) {
                nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError,
                    "I2C(%d) does not exist", i2c_id));
            }
        }
    
        // get I2C object
        const pyb_i2c_obj_t *i2c_obj = &pyb_i2c_obj[i2c_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_i2c_init_helper(i2c_obj, n_args - 1, args + 1, &kw_args);
        }
    
        return (mp_obj_t)i2c_obj;
    }
    
    STATIC mp_obj_t pyb_i2c_init(mp_uint_t n_args, const mp_obj_t *args, mp_map_t *kw_args) {
        return pyb_i2c_init_helper(args[0], n_args - 1, args + 1, kw_args);
    }
    STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_i2c_init_obj, 1, pyb_i2c_init);
    
    /// \method deinit()
    /// Turn off the I2C bus.
    STATIC mp_obj_t pyb_i2c_deinit(mp_obj_t self_in) {
        pyb_i2c_obj_t *self = self_in;
        i2c_deinit(self->i2c);
        return mp_const_none;
    }
    STATIC MP_DEFINE_CONST_FUN_OBJ_1(pyb_i2c_deinit_obj, pyb_i2c_deinit);
    
    /// \method is_ready(addr)
    /// Check if an I2C device responds to the given address.  Only valid when in master mode.
    STATIC mp_obj_t pyb_i2c_is_ready(mp_obj_t self_in, mp_obj_t i2c_addr_o) {
        pyb_i2c_obj_t *self = self_in;
    
        if (!in_master_mode(self)) {
            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "I2C must be a master"));
        }
    
        mp_uint_t i2c_addr = mp_obj_get_int(i2c_addr_o) << 1;
    
        for (int i = 0; i < 10; i++) {
            HAL_StatusTypeDef status = HAL_I2C_IsDeviceReady(self->i2c, i2c_addr, 10, 200);
            if (status == HAL_OK) {
                return mp_const_true;
            }
        }
    
        return mp_const_false;
    }
    STATIC MP_DEFINE_CONST_FUN_OBJ_2(pyb_i2c_is_ready_obj, pyb_i2c_is_ready);
    
    /// \method scan()
    /// Scan all I2C addresses from 0x08 to 0x77 and return a list of those that respond.
    /// Only valid when in master mode.
    STATIC mp_obj_t pyb_i2c_scan(mp_obj_t self_in) {
        pyb_i2c_obj_t *self = self_in;
    
        if (!in_master_mode(self)) {
            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "I2C must be a master"));
        }
    
        mp_obj_t list = mp_obj_new_list(0, NULL);
    
        for (uint addr = 0x08; addr <= 0x77; addr++) {
            for (int i = 0; i < 10; i++) {
                HAL_StatusTypeDef status = HAL_I2C_IsDeviceReady(self->i2c, addr << 1, 10, 200);
                if (status == HAL_OK) {
                    mp_obj_list_append(list, mp_obj_new_int(addr));
                    break;
                }
            }
        }
    
        return list;
    }
    STATIC MP_DEFINE_CONST_FUN_OBJ_1(pyb_i2c_scan_obj, pyb_i2c_scan);
    
    /// \method send(send, addr=0x00, timeout=5000)
    /// Send data on the bus:
    ///
    ///   - `send` is the data to send (an integer to send, or a buffer object)
    ///   - `addr` is the address to send to (only required in master mode)
    ///   - `timeout` is the timeout in milliseconds to wait for the send
    ///
    /// Return value: `None`.
    STATIC mp_obj_t pyb_i2c_send(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_send,    MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
            { MP_QSTR_addr,    MP_ARG_INT, {.u_int = PYB_I2C_MASTER_ADDRESS} },
            { MP_QSTR_timeout, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 5000} },
        };
    
        // parse args
        pyb_i2c_obj_t *self = pos_args[0];
        mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
        mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
    
        // get the buffer to send from
        mp_buffer_info_t bufinfo;
        uint8_t data[1];
        pyb_buf_get_for_send(args[0].u_obj, &bufinfo, data);
    
        // if option is set and IRQs are enabled then we can use DMA
        bool use_dma = *self->use_dma && query_irq() == IRQ_STATE_ENABLED;
    
        DMA_HandleTypeDef tx_dma;
        if (use_dma) {
            dma_init(&tx_dma, self->tx_dma_descr, self->i2c);
            self->i2c->hdmatx = &tx_dma;
            self->i2c->hdmarx = NULL;
        }
    
        // send the data
        HAL_StatusTypeDef status;
        if (in_master_mode(self)) {
            if (args[1].u_int == PYB_I2C_MASTER_ADDRESS) {
                if (use_dma) {
                    dma_deinit(self->tx_dma_descr);
                }
                nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "addr argument required"));
            }
            mp_uint_t i2c_addr = args[1].u_int << 1;
            if (!use_dma) {
                status = HAL_I2C_Master_Transmit(self->i2c, i2c_addr, bufinfo.buf, bufinfo.len, args[2].u_int);
            } else {
                MP_HAL_CLEAN_DCACHE(bufinfo.buf, bufinfo.len);
                status = HAL_I2C_Master_Transmit_DMA(self->i2c, i2c_addr, bufinfo.buf, bufinfo.len);
            }
        } else {
            if (!use_dma) {
                status = HAL_I2C_Slave_Transmit(self->i2c, bufinfo.buf, bufinfo.len, args[2].u_int);
            } else {
                MP_HAL_CLEAN_DCACHE(bufinfo.buf, bufinfo.len);
                status = HAL_I2C_Slave_Transmit_DMA(self->i2c, bufinfo.buf, bufinfo.len);
            }
        }
    
        // if we used DMA, wait for it to finish
        if (use_dma) {
            if (status == HAL_OK) {
                status = i2c_wait_dma_finished(self->i2c, args[2].u_int);
            }
            dma_deinit(self->tx_dma_descr);
        }
    
        if (status != HAL_OK) {
            i2c_reset_after_error(self->i2c);
            mp_hal_raise(status);
        }
    
        return mp_const_none;
    }
    STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_i2c_send_obj, 1, pyb_i2c_send);
    
    /// \method recv(recv, addr=0x00, 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
    ///   - `addr` is the address to receive from (only required in master mode)
    ///   - `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 mp_obj_t pyb_i2c_recv(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_recv,    MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
            { MP_QSTR_addr,    MP_ARG_INT, {.u_int = PYB_I2C_MASTER_ADDRESS} },
            { MP_QSTR_timeout, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 5000} },
        };
    
        // parse args
        pyb_i2c_obj_t *self = pos_args[0];
        mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
        mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
    
        // get the buffer to receive into
        vstr_t vstr;
        mp_obj_t o_ret = pyb_buf_get_for_recv(args[0].u_obj, &vstr);
    
        // if option is set and IRQs are enabled then we can use DMA
        bool use_dma = *self->use_dma && query_irq() == IRQ_STATE_ENABLED;
    
        DMA_HandleTypeDef rx_dma;
        if (use_dma) {
            dma_init(&rx_dma, self->rx_dma_descr, self->i2c);
            self->i2c->hdmatx = NULL;
            self->i2c->hdmarx = &rx_dma;
        }
    
        // receive the data
        HAL_StatusTypeDef status;
        if (in_master_mode(self)) {
            if (args[1].u_int == PYB_I2C_MASTER_ADDRESS) {
                nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "addr argument required"));
            }
            mp_uint_t i2c_addr = args[1].u_int << 1;
            if (!use_dma) {
                status = HAL_I2C_Master_Receive(self->i2c, i2c_addr, (uint8_t*)vstr.buf, vstr.len, args[2].u_int);
            } else {
                MP_HAL_CLEANINVALIDATE_DCACHE(vstr.buf, vstr.len);
                status = HAL_I2C_Master_Receive_DMA(self->i2c, i2c_addr, (uint8_t*)vstr.buf, vstr.len);
            }
        } else {
            if (!use_dma) {
                status = HAL_I2C_Slave_Receive(self->i2c, (uint8_t*)vstr.buf, vstr.len, args[2].u_int);
            } else {
                MP_HAL_CLEANINVALIDATE_DCACHE(vstr.buf, vstr.len);
                status = HAL_I2C_Slave_Receive_DMA(self->i2c, (uint8_t*)vstr.buf, vstr.len);
            }
        }
    
        // if we used DMA, wait for it to finish
        if (use_dma) {
            if (status == HAL_OK) {
                status = i2c_wait_dma_finished(self->i2c, args[2].u_int);
            }
            dma_deinit(self->rx_dma_descr);
        }
    
        if (status != HAL_OK) {
            i2c_reset_after_error(self->i2c);
            mp_hal_raise(status);
        }
    
        // return the received data
        if (o_ret != MP_OBJ_NULL) {
            return o_ret;
        } else {
            return mp_obj_new_str_from_vstr(&mp_type_bytes, &vstr);
        }
    }
    STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_i2c_recv_obj, 1, pyb_i2c_recv);
    
    /// \method mem_read(data, addr, memaddr, timeout=5000, addr_size=8)
    ///
    /// Read from the memory of an I2C device:
    ///
    ///   - `data` can be an integer or a buffer to read into
    ///   - `addr` is the I2C device address
    ///   - `memaddr` is the memory location within the I2C device
    ///   - `timeout` is the timeout in milliseconds to wait for the read
    ///   - `addr_size` selects width of memaddr: 8 or 16 bits
    ///
    /// Returns the read data.
    /// This is only valid in master mode.
    STATIC const mp_arg_t pyb_i2c_mem_read_allowed_args[] = {
        { MP_QSTR_data,    MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
        { MP_QSTR_addr,    MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = 0} },
        { MP_QSTR_memaddr, MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = 0} },
        { MP_QSTR_timeout, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 5000} },
        { MP_QSTR_addr_size, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 8} },
    };
    
    STATIC mp_obj_t pyb_i2c_mem_read(mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
        // parse args
        pyb_i2c_obj_t *self = pos_args[0];
        mp_arg_val_t args[MP_ARRAY_SIZE(pyb_i2c_mem_read_allowed_args)];
        mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args, MP_ARRAY_SIZE(pyb_i2c_mem_read_allowed_args), pyb_i2c_mem_read_allowed_args, args);
    
        if (!in_master_mode(self)) {
            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "I2C must be a master"));
        }
    
        // get the buffer to read into
        vstr_t vstr;
        mp_obj_t o_ret = pyb_buf_get_for_recv(args[0].u_obj, &vstr);
    
        // get the addresses
        mp_uint_t i2c_addr = args[1].u_int << 1;
        mp_uint_t mem_addr = args[2].u_int;
        // determine width of mem_addr; default is 8 bits, entering any other value gives 16 bit width
        mp_uint_t mem_addr_size = I2C_MEMADD_SIZE_8BIT;
        if (args[4].u_int != 8) {
            mem_addr_size = I2C_MEMADD_SIZE_16BIT;
        }
    
        // if option is set and IRQs are enabled then we can use DMA
        bool use_dma = *self->use_dma && query_irq() == IRQ_STATE_ENABLED;
    
        HAL_StatusTypeDef status;
        if (!use_dma) {
            status = HAL_I2C_Mem_Read(self->i2c, i2c_addr, mem_addr, mem_addr_size, (uint8_t*)vstr.buf, vstr.len, args[3].u_int);
        } else {
            DMA_HandleTypeDef rx_dma;
            dma_init(&rx_dma, self->rx_dma_descr, self->i2c);
            self->i2c->hdmatx = NULL;
            self->i2c->hdmarx = &rx_dma;
            MP_HAL_CLEANINVALIDATE_DCACHE(vstr.buf, vstr.len);
            status = HAL_I2C_Mem_Read_DMA(self->i2c, i2c_addr, mem_addr, mem_addr_size, (uint8_t*)vstr.buf, vstr.len);
            if (status == HAL_OK) {
                status = i2c_wait_dma_finished(self->i2c, args[3].u_int);
            }
            dma_deinit(self->rx_dma_descr);
        }
    
        if (status != HAL_OK) {
            i2c_reset_after_error(self->i2c);
            mp_hal_raise(status);
        }
    
        // return the read data
        if (o_ret != MP_OBJ_NULL) {
            return o_ret;
        } else {
            return mp_obj_new_str_from_vstr(&mp_type_bytes, &vstr);
        }
    }
    STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_i2c_mem_read_obj, 1, pyb_i2c_mem_read);
    
    /// \method mem_write(data, addr, memaddr, timeout=5000, addr_size=8)
    ///
    /// Write to the memory of an I2C device:
    ///
    ///   - `data` can be an integer or a buffer to write from
    ///   - `addr` is the I2C device address
    ///   - `memaddr` is the memory location within the I2C device
    ///   - `timeout` is the timeout in milliseconds to wait for the write
    ///   - `addr_size` selects width of memaddr: 8 or 16 bits
    ///
    /// Returns `None`.
    /// This is only valid in master mode.
    STATIC mp_obj_t pyb_i2c_mem_write(mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
        // parse args (same as mem_read)
        pyb_i2c_obj_t *self = pos_args[0];
        mp_arg_val_t args[MP_ARRAY_SIZE(pyb_i2c_mem_read_allowed_args)];
        mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args, MP_ARRAY_SIZE(pyb_i2c_mem_read_allowed_args), pyb_i2c_mem_read_allowed_args, args);
    
        if (!in_master_mode(self)) {
            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "I2C must be a master"));
        }
    
        // get the buffer to write from
        mp_buffer_info_t bufinfo;
        uint8_t data[1];
        pyb_buf_get_for_send(args[0].u_obj, &bufinfo, data);
    
        // get the addresses
        mp_uint_t i2c_addr = args[1].u_int << 1;
        mp_uint_t mem_addr = args[2].u_int;
        // determine width of mem_addr; default is 8 bits, entering any other value gives 16 bit width
        mp_uint_t mem_addr_size = I2C_MEMADD_SIZE_8BIT;
        if (args[4].u_int != 8) {
            mem_addr_size = I2C_MEMADD_SIZE_16BIT;
        }
    
        // if option is set and IRQs are enabled then we can use DMA
        bool use_dma = *self->use_dma && query_irq() == IRQ_STATE_ENABLED;
    
        HAL_StatusTypeDef status;
        if (!use_dma) {
            status = HAL_I2C_Mem_Write(self->i2c, i2c_addr, mem_addr, mem_addr_size, bufinfo.buf, bufinfo.len, args[3].u_int);
        } else {
            DMA_HandleTypeDef tx_dma;
            dma_init(&tx_dma, self->tx_dma_descr, self->i2c);
            self->i2c->hdmatx = &tx_dma;
            self->i2c->hdmarx = NULL;
            MP_HAL_CLEAN_DCACHE(bufinfo.buf, bufinfo.len);
            status = HAL_I2C_Mem_Write_DMA(self->i2c, i2c_addr, mem_addr, mem_addr_size, bufinfo.buf, bufinfo.len);
            if (status == HAL_OK) {
                status = i2c_wait_dma_finished(self->i2c, args[3].u_int);
            }
            dma_deinit(self->tx_dma_descr);
        }
    
        if (status != HAL_OK) {
            i2c_reset_after_error(self->i2c);
            mp_hal_raise(status);
        }
    
        return mp_const_none;
    }
    STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_i2c_mem_write_obj, 1, pyb_i2c_mem_write);
    
    STATIC const mp_map_elem_t pyb_i2c_locals_dict_table[] = {
        // instance methods
        { MP_OBJ_NEW_QSTR(MP_QSTR_init), (mp_obj_t)&pyb_i2c_init_obj },
        { MP_OBJ_NEW_QSTR(MP_QSTR_deinit), (mp_obj_t)&pyb_i2c_deinit_obj },
        { MP_OBJ_NEW_QSTR(MP_QSTR_is_ready), (mp_obj_t)&pyb_i2c_is_ready_obj },
        { MP_OBJ_NEW_QSTR(MP_QSTR_scan), (mp_obj_t)&pyb_i2c_scan_obj },
        { MP_OBJ_NEW_QSTR(MP_QSTR_send), (mp_obj_t)&pyb_i2c_send_obj },
        { MP_OBJ_NEW_QSTR(MP_QSTR_recv), (mp_obj_t)&pyb_i2c_recv_obj },
        { MP_OBJ_NEW_QSTR(MP_QSTR_mem_read), (mp_obj_t)&pyb_i2c_mem_read_obj },
        { MP_OBJ_NEW_QSTR(MP_QSTR_mem_write), (mp_obj_t)&pyb_i2c_mem_write_obj },
    
        // class constants
        /// \constant MASTER - for initialising the bus to master mode
        /// \constant SLAVE - for initialising the bus to slave mode
        { MP_OBJ_NEW_QSTR(MP_QSTR_MASTER),       MP_OBJ_NEW_SMALL_INT(PYB_I2C_MASTER) },
        { MP_OBJ_NEW_QSTR(MP_QSTR_SLAVE),        MP_OBJ_NEW_SMALL_INT(PYB_I2C_SLAVE) },
    };
    
    STATIC MP_DEFINE_CONST_DICT(pyb_i2c_locals_dict, pyb_i2c_locals_dict_table);
    
    const mp_obj_type_t pyb_i2c_type = {
        { &mp_type_type },
        .name = MP_QSTR_I2C,
        .print = pyb_i2c_print,
        .make_new = pyb_i2c_make_new,
        .locals_dict = (mp_obj_t)&pyb_i2c_locals_dict,
    };