ESP32学习笔记（四）之I2C总线

/* i2c - Example

   For other examples please check:
   https://github.com/espressif/esp-idf/tree/master/examples

   This example code is in the Public Domain (or CC0 licensed, at your option.)

   Unless required by applicable law or agreed to in writing, this
   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
   CONDITIONS OF ANY KIND, either express or implied.
*/
#include <stdio.h>
#include "driver/i2c.h"
#include <freertos/FreeRTOS.h>
#include <freertos/task.h>
#include "sdkconfig.h"

#include "esp_log.h"
#include "esp_spi_flash.h"
#include "esp_system.h"



#define SCL_PIN          19               /*!< gpio number for I2C master clock */
#define SDA_PIN          18               /*!< gpio number for I2C master data  */
#define ESP_SLAVE_ADDR  0x48


#define WRITE_BIT                          I2C_MASTER_WRITE /*!< I2C master write */
#define READ_BIT                           I2C_MASTER_READ  /*!< I2C master read */
#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 */
#define ACK_VAL                            0x0              /*!< I2C ack value */
#define NACK_VAL                           0x1              /*!< I2C nack value */


uint8_t Temp[2];

/**
 * @brief test code to read esp-i2c-slave
 *        We need to fill the buffer of esp slave device, then master can read them out.
 *
 * _______________________________________________________________________________________
 * | start | slave_addr + rd_bit +ack | read n-1 bytes + ack | read 1 byte + nack | stop |
 * --------|--------------------------|----------------------|--------------------|------|
 *
 */
static esp_err_t i2c_read(i2c_port_t i2c_num, uint8_t* data_rd, size_t size)
{
    if (size == 0) {
        return ESP_OK;
    }
    i2c_cmd_handle_t cmd = i2c_cmd_link_create();
    i2c_master_start(cmd);
    i2c_master_write_byte(cmd, ( ESP_SLAVE_ADDR << 1 ) | READ_BIT, ACK_CHECK_EN);
    if (size > 1) {
        i2c_master_read(cmd, data_rd, size - 1, ACK_VAL);
    }
    i2c_master_read_byte(cmd, data_rd + size - 1, NACK_VAL);
    i2c_master_stop(cmd);
    esp_err_t ret = i2c_master_cmd_begin(i2c_num, cmd, 1000 / portTICK_RATE_MS);
    i2c_cmd_link_delete(cmd);
    return ret;
}

/**
 * @brief Test code to write esp-i2c-slave
 *        Master device write data to slave(both esp32),
 *        the data will be stored in slave buffer.
 *        We can read them out from slave buffer.
 *
 * ___________________________________________________________________
 * | start | slave_addr + wr_bit + ack | write n bytes + ack  | stop |
 * --------|---------------------------|----------------------|------|
 *
 */
static esp_err_t i2c_write(i2c_port_t i2c_num, uint8_t* data_wr, size_t size)
{
    i2c_cmd_handle_t cmd = i2c_cmd_link_create();
    i2c_master_start(cmd);
    i2c_master_write_byte(cmd, ( ESP_SLAVE_ADDR << 1 ) | WRITE_BIT, ACK_CHECK_EN);
    i2c_master_write(cmd, data_wr, size, ACK_CHECK_EN);
    i2c_master_stop(cmd);
    esp_err_t ret = i2c_master_cmd_begin(i2c_num, cmd, 1000 / portTICK_RATE_MS);
    i2c_cmd_link_delete(cmd);
    return ret;
}




void LM75a_test(void *pvParameter)
{
    uint16_t Temp_Sum;
    uint8_t n,i,Tem_Reg = 0x00;
    float Temp_ALL;
    char buffer[20];
    
    while(1){    
        i2c_write(I2C_NUM_0, &Tem_Reg, sizeof(Tem_Reg));
        i2c_read(I2C_NUM_0, (uint8_t *)Temp,sizeof(Temp));
       
        Temp_Sum = Temp[0];                   //count  LM75a
        Temp_Sum <<= 8;
        Temp_Sum |= Temp[1];
        Temp_Sum >>= 5;
        Temp_ALL = (float)Temp_Sum * 0.125;
       
        n=sprintf (buffer, "%f",Temp_ALL);
        printf("The temp is: ");
        for(i = 0; i < n; i++)
            printf("%c",buffer[i]);
        printf("  C");
        printf("\n");
        vTaskDelay(1000 / portTICK_PERIOD_MS);

    }
}   



/**
 * @brief i2c master initialization
 */
static void i2c_master_init()
{
    i2c_config_t conf;
    conf.mode = I2C_MODE_MASTER;
    conf.sda_io_num = SDA_PIN;
    conf.scl_io_num = SCL_PIN;
    conf.sda_pullup_en = GPIO_PULLUP_ENABLE;
    conf.scl_pullup_en = GPIO_PULLUP_ENABLE;
    conf.master.clk_speed = 100000;
    i2c_param_config(I2C_NUM_0, &conf);

    i2c_driver_install(I2C_NUM_0, I2C_MODE_MASTER, 0, 0, 0);
}




void app_main()
{

    i2c_master_init();
    xTaskCreate(LM75a_test, "LM75a_test", 1024 * 2, NULL, 9, NULL);

}