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98 lines
3.7 KiB
C
98 lines
3.7 KiB
C
/* i2c - Simple example
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Simple I2C example that shows how to initialize I2C
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as well as reading and writing from and to registers for a sensor connected over I2C.
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The sensor used in this example is a MPU9250 inertial measurement unit.
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For other examples please check:
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https://github.com/espressif/esp-idf/tree/master/examples
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See README.md file to get detailed usage of this example.
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This example code is in the Public Domain (or CC0 licensed, at your option.)
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Unless required by applicable law or agreed to in writing, this
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software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
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CONDITIONS OF ANY KIND, either express or implied.
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*/
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#include <stdio.h>
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#include "esp_log.h"
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#include "driver/i2c.h"
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static const char *TAG = "i2c-simple-example";
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#define I2C_MASTER_SCL_IO CONFIG_I2C_MASTER_SCL /*!< GPIO number used for I2C master clock */
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#define I2C_MASTER_SDA_IO CONFIG_I2C_MASTER_SDA /*!< GPIO number used for I2C master data */
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#define I2C_MASTER_NUM 0 /*!< I2C master i2c port number, the number of i2c peripheral interfaces available will depend on the chip */
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#define I2C_MASTER_FREQ_HZ 400000 /*!< I2C master clock frequency */
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#define I2C_MASTER_TX_BUF_DISABLE 0 /*!< I2C master doesn't need buffer */
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#define I2C_MASTER_RX_BUF_DISABLE 0 /*!< I2C master doesn't need buffer */
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#define I2C_MASTER_TIMEOUT_MS 1000
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#define MPU9250_SENSOR_ADDR 0x68 /*!< Slave address of the MPU9250 sensor */
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#define MPU9250_WHO_AM_I_REG_ADDR 0x75 /*!< Register addresses of the "who am I" register */
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#define MPU9250_PWR_MGMT_1_REG_ADDR 0x6B /*!< Register addresses of the power managment register */
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#define MPU9250_RESET_BIT 7
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/**
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* @brief Read a sequence of bytes from a MPU9250 sensor registers
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*/
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static esp_err_t mpu9250_register_read(uint8_t reg_addr, uint8_t *data, size_t len)
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{
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return i2c_master_write_read_device(I2C_MASTER_NUM, MPU9250_SENSOR_ADDR, ®_addr, 1, data, len, I2C_MASTER_TIMEOUT_MS / portTICK_RATE_MS);
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}
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/**
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* @brief Write a byte to a MPU9250 sensor register
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*/
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static esp_err_t mpu9250_register_write_byte(uint8_t reg_addr, uint8_t data)
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{
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int ret;
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uint8_t write_buf[2] = {reg_addr, data};
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ret = i2c_master_write_to_device(I2C_MASTER_NUM, MPU9250_SENSOR_ADDR, write_buf, sizeof(write_buf), I2C_MASTER_TIMEOUT_MS / portTICK_RATE_MS);
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return ret;
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}
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/**
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* @brief i2c master initialization
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*/
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static esp_err_t i2c_master_init(void)
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{
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int i2c_master_port = I2C_MASTER_NUM;
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i2c_config_t conf = {
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.mode = I2C_MODE_MASTER,
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.sda_io_num = I2C_MASTER_SDA_IO,
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.scl_io_num = I2C_MASTER_SCL_IO,
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.sda_pullup_en = GPIO_PULLUP_ENABLE,
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.scl_pullup_en = GPIO_PULLUP_ENABLE,
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.master.clk_speed = I2C_MASTER_FREQ_HZ,
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};
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i2c_param_config(i2c_master_port, &conf);
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return i2c_driver_install(i2c_master_port, conf.mode, I2C_MASTER_RX_BUF_DISABLE, I2C_MASTER_TX_BUF_DISABLE, 0);
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}
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void app_main(void)
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{
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uint8_t data[2];
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ESP_ERROR_CHECK(i2c_master_init());
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ESP_LOGI(TAG, "I2C initialized successfully");
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/* Read the MPU9250 WHO_AM_I register, on power up the register should have the value 0x71 */
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ESP_ERROR_CHECK(mpu9250_register_read(MPU9250_WHO_AM_I_REG_ADDR, data, 1));
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ESP_LOGI(TAG, "WHO_AM_I = %X", data[0]);
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/* Demonstrate writing by reseting the MPU9250 */
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ESP_ERROR_CHECK(mpu9250_register_write_byte(MPU9250_PWR_MGMT_1_REG_ADDR, 1 << MPU9250_RESET_BIT));
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ESP_ERROR_CHECK(i2c_driver_delete(I2C_MASTER_NUM));
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ESP_LOGI(TAG, "I2C unitialized successfully");
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}
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