esp32 iic驱动

ESP32支持多种I2C驱动，包括硬件I2C和软件I2C。下面是一个使用硬件I2C的例子：

1. 首先，使用`i2c_master_init`函数初始化I2C总线：

#include "driver/i2c.h"

#define I2C_MASTER_SCL_IO    19          /*!< gpio number for I2C master clock */
#define I2C_MASTER_SDA_IO    18          /*!< gpio number for I2C master data  */
#define I2C_MASTER_NUM       I2C_NUM_0   /*!< I2C port number for master dev */
#define I2C_MASTER_FREQ_HZ   100000      /*!< I2C master clock frequency */

i2c_config_t conf;
conf.mode = I2C_MODE_MASTER;
conf.sda_io_num = I2C_MASTER_SDA_IO;
conf.sda_pullup_en = GPIO_PULLUP_ENABLE;
conf.scl_io_num = I2C_MASTER_SCL_IO;
conf.scl_pullup_en = GPIO_PULLUP_ENABLE;
conf.master.clk_speed = I2C_MASTER_FREQ_HZ;
i2c_param_config(I2C_MASTER_NUM, &conf);
i2c_driver_install(I2C_MASTER_NUM, conf.mode, 0, 0, 0);

2. 使用`i2c_cmd_link_create`函数创建一个I2C传输链路：

i2c_cmd_handle_t cmd_handle = i2c_cmd_link_create();

3. 添加I2C传输命令：

#define I2C_SLAVE_ADDR 0x68
#define I2C_REG_ADDR 0x00

i2c_master_start(cmd_handle);
i2c_master_write_byte(cmd_handle, (I2C_SLAVE_ADDR << 1) | I2C_MASTER_WRITE, true);
i2c_master_write_byte(cmd_handle, I2C_REG_ADDR, true);
i2c_master_start(cmd_handle);
i2c_master_write_byte(cmd_handle, (I2C_SLAVE_ADDR << 1) | I2C_MASTER_READ, true);
i2c_master_read_byte(cmd_handle, &data, I2C_MASTER_ACK);
i2c_master_stop(cmd_handle);

4. 执行I2C传输：

esp_err_t ret = i2c_master_cmd_begin(I2C_MASTER_NUM, cmd_handle, 1000 / portTICK_RATE_MS);
if (ret != ESP_OK) {
    printf("I2C Error: %d\n", ret);
}

完整的I2C读取代码：

#include "driver/i2c.h"

#define I2C_MASTER_SCL_IO    19          /*!< gpio number for I2C master clock */
#define I2C_MASTER_SDA_IO    18          /*!< gpio number for I2C master data  */
#define I2C_MASTER_NUM       I2C_NUM_0   /*!< I2C port number for master dev */
#define I2C_MASTER_FREQ_HZ   100000      /*!< I2C master clock frequency */

void i2c_master_init() {
    i2c_config_t conf;
    conf.mode = I2C_MODE_MASTER;
    conf.sda_io_num = I2C_MASTER_SDA_IO;
    conf.sda_pullup_en = GPIO_PULLUP_ENABLE;
    conf.scl_io_num = I2C_MASTER_SCL_IO;
    conf.scl_pullup_en = GPIO_PULLUP_ENABLE;
    conf.master.clk_speed = I2C_MASTER_FREQ_HZ;
    i2c_param_config(I2C_MASTER_NUM, &conf);
    i2c_driver_install(I2C_MASTER_NUM, conf.mode, 0, 0, 0);
}

void i2c_master_read(uint8_t slave_address, uint8_t reg_address, uint8_t* data, uint8_t length) {
    i2c_cmd_handle_t cmd_handle = i2c_cmd_link_create();
    i2c_master_start(cmd_handle);
    i2c_master_write_byte(cmd_handle, (slave_address << 1) | I2C_MASTER_WRITE, true);
    i2c_master_write_byte(cmd_handle, reg_address, true);
    i2c_master_start(cmd_handle);
    i2c_master_write_byte(cmd_handle, (slave_address << 1) | I2C_MASTER_READ, true);
    for (int i = 0; i < length; i++) {
        i2c_master_read_byte(cmd_handle, data + i, I2C_MASTER_ACK);
    }
    i2c_master_stop(cmd_handle);
    esp_err_t ret = i2c_master_cmd_begin(I2C_MASTER_NUM, cmd_handle, 1000 / portTICK_RATE_MS);
    if (ret != ESP_OK) {
        printf("I2C Error: %d\n", ret);
    }
    i2c_cmd_link_delete(cmd_handle);
}