esp32 i2c with mutex

master_i2c.c

#include "master_i2c.h"
#include <driver/i2c.h>
#include <esp_log.h>
#include <freertos/FreeRTOS.h>

#define ACK_CHECK_EN 0x1 //!< I2C master will check ack from slave
#define ACK_CHECK_DIS 0x0 //!< I2C master will not check ack from slave

static SemaphoreHandle_t i2c_semaphore = NULL;

esp_err_t master_i2c_init()
{
    // Don't initialize twice
    if(i2c_semaphore != NULL)
        return ESP_FAIL;

    i2c_semaphore = xSemaphoreCreateMutex();
    if(i2c_semaphore == NULL)
        return ESP_FAIL;

    i2c_config_t conf = {
        .mode = I2C_MODE_MASTER,
        .sda_io_num = CONFIG_I2C_SDA_GPIO,
        .sda_pullup_en = GPIO_PULLUP_ENABLE,
        .scl_io_num = CONFIG_I2C_SCL_GPIO,
        .scl_pullup_en = GPIO_PULLUP_ENABLE,
        .master.clk_speed = CONFIG_I2C_FREQ_KHZ * 1000,
    };

    esp_err_t ret;

    ret = i2c_param_config(I2C_NUM_1, &conf);
    if(ret != ESP_OK)
        return ret;

    ret = i2c_driver_install(I2C_NUM_1, conf.mode, 0, 0, 0);
    if(ret != ESP_OK)
        return ret;

    return ESP_OK;
}

void master_i2c_write(uint8_t address, uint8_t reg, uint8_t* data, uint32_t size)
{
    i2c_cmd_handle_t cmd = i2c_cmd_link_create();
    i2c_master_start(cmd);
    i2c_master_write_byte(cmd, address << 1 | I2C_MASTER_WRITE, ACK_CHECK_EN);
    i2c_master_write_byte(cmd, reg, ACK_CHECK_EN);
    i2c_master_write(cmd, data, size, ACK_CHECK_EN);
    i2c_master_stop(cmd);

    xSemaphoreTake(i2c_semaphore, portMAX_DELAY);
    i2c_master_cmd_begin(I2C_NUM_1, cmd, 0);
    xSemaphoreGive(i2c_semaphore);

    i2c_cmd_link_delete(cmd);
}

void master_i2c_read(uint8_t address, uint8_t reg, uint8_t* data, uint32_t size)
{
    // Write the active address to the I2C device
    i2c_cmd_handle_t cmd = i2c_cmd_link_create();
    i2c_master_start(cmd);
    i2c_master_write_byte(cmd, address << 1 | I2C_MASTER_WRITE, ACK_CHECK_EN);
    i2c_master_write_byte(cmd, reg, ACK_CHECK_EN);

    // Then read the contents of that address
    i2c_master_start(cmd);
    i2c_master_write_byte(cmd, address << 1 | I2C_MASTER_READ, ACK_CHECK_EN);
    i2c_master_read(cmd, data, size, I2C_MASTER_LAST_NACK);
    i2c_master_stop(cmd);

    xSemaphoreTake(i2c_semaphore, portMAX_DELAY);
    i2c_master_cmd_begin(I2C_NUM_1, cmd, 0);
    xSemaphoreGive(i2c_semaphore);

    i2c_cmd_link_delete(cmd);
}

master_i2c.h

#pragma once

#include <stdint.h>
#include <esp_err.h>

//! @defgroup master_i2c Master I2C driver
//!
//! @brief Thread-safe Master I2C driver
//!
//! This driver uses the I2C_NUM_1 peripheral on the ESP32. Functions are multi-
//! thread safe, protected by an internal semaphore.
//! @{

//! @brief Initialize the I2C bus in master mode
//!
esp_err_t master_i2c_init();

//! @brief Make a write transaction on the I2C bus
//!
//! @param[in] address Address of I2C bus to write to (7-bit address, right-aligned)
//! @param[in] reg I2C register to write to
//! @param[in] data Pointer to memory location to read data from
//! @param[in] size Number of bytes to write
void master_i2c_write(uint8_t address, uint8_t reg, uint8_t* data, uint32_t size);

//! @brief Make a read transaction on the I2C bus
//!
//! @param[in] address Address of I2C bus to read from(7-bit address, right-aligned)
//! @param[in] reg I2C register to read from
//! @param[out] data Pointer to memory location to write data to
//! @param[in] size Number of bytes to read
void master_i2c_read(uint8_t address, uint8_t reg, uint8_t* data, uint32_t size);

//! @}

Found this while looking for solutions to some corrupt I2C reads while running internet streaming & Bluetooth A2DP code that uses both cores.

Seems like I need to protect the I2C reads so they are not interrupted while running.

I'm using the ESP32 with the Arduino environment via Platform IO.

How do I best put this code to use? Just add the .h & .c pages to my project and use the master_i2c_read commands instead of the wire commands since I'm currently using the EPS32 Arduino environment Wire library which is not thread safe.

Just looking to get I2C stable so I can move onto other task and I assume you created this because you had a similar issue you needed to solve.

Any advice is appreciated.

Hope you've got this working already. I don't have experience with the Arduino environment for ESP, but you 'just' need to put a semaphore around any calls to I2C. I think it would be better to make a wrapper around your calls to wire, rather than using the ESP I2C interface directly. Good luck!