i2c: add a simple i2c sensor communication example

examples/peripherals/i2c/i2c_simple/CMakeLists.txt

@@ -0,0 +1,6 @@
+# The following lines of boilerplate have to be in your project's CMakeLists
+# in this exact order for cmake to work correctly
+cmake_minimum_required(VERSION 3.5)
+
+include($ENV{IDF_PATH}/tools/cmake/project.cmake)
+project(i2c-simple)

examples/peripherals/i2c/i2c_simple/Makefile

@@ -0,0 +1,8 @@
+#
+# This is a project Makefile. It is assumed the directory this Makefile resides in is a
+# project subdirectory.
+#
+
+PROJECT_NAME := i2c-simple
+
+include $(IDF_PATH)/make/project.mk

examples/peripherals/i2c/i2c_simple/README.md

@@ -0,0 +1,49 @@
+# I2C Simple Example
+
+(See the README.md file in the upper level 'examples' directory for more information about examples.)
+
+## Overview
+
+This example demonstrates basic usage of I2C driver by reading and writing from a I2C connected sensor:
+
+If you have a new I2C application to go (for example, read the temperature data from external sensor with I2C interface), try this as a basic template, then add your own code.
+
+## How to use example
+
+### Hardware Required
+
+To run this example, you should have one ESP32, ESP32-S or ESP32-C based development board as well as a MPU9250. MPU9250 is a inertial measurement unit, which contains a accelerometer, gyroscope as well as a magnetometer, for more information about it, you can read the [PDF](https://invensense.tdk.com/wp-content/uploads/2015/02/PS-MPU-9250A-01-v1.1.pdf) of this sensor.
+
+#### Pin Assignment:
+
+**Note:** The following pin assignments are used by default, you can change these in the `menuconfig` .
+
+|                  | SDA             | SCL           |
+| ---------------- | -------------- | -------------- |
+| ESP I2C Master   | I2C_MASTER_SDA | I2C_MASTER_SCL |
+| MPU9250 Sensor   | SDA            | SCL            |
+
+
+For the actual default value of `I2C_MASTER_SDA` and `I2C_MASTER_SCL` see `Example Configuration` in `menuconfig`.
+
+**Note: ** There’s no need to add an external pull-up resistors for SDA/SCL pin, because the driver will enable the internal pull-up resistors.
+
+### Build and Flash
+
+Enter `idf.py -p PORT flash monitor` to build, flash and monitor the project.
+
+(To exit the serial monitor, type ``Ctrl-]``.)
+
+See the [Getting Started Guide](https://docs.espressif.com/projects/esp-idf/en/latest/get-started/index.html) for full steps to configure and use ESP-IDF to build projects.
+
+## Example Output
+
+```bash
+I (328) i2c-simple-example: I2C initialized successfully
+I (338) i2c-simple-example: WHO_AM_I = 71
+I (338) i2c-simple-example: I2C unitialized successfully
+```
+
+## Troubleshooting
+
+(For any technical queries, please open an [issue](https://github.com/espressif/esp-idf/issues) on GitHub. We will get back to you as soon as possible.)

examples/peripherals/i2c/i2c_simple/main/CMakeLists.txt

@@ -0,0 +1,2 @@
+idf_component_register(SRCS "i2c_simple_main.c"
+                    INCLUDE_DIRS ".")

examples/peripherals/i2c/i2c_simple/main/Kconfig.projbuild

@@ -0,0 +1,17 @@
+menu "Example Configuration"
+
+    config I2C_MASTER_SCL
+        int "SCL GPIO Num"
+        default 6 if IDF_TARGET_ESP32C3
+        default 19 if IDF_TARGET_ESP32 || IDF_TARGET_ESP32S2 || IDF_TARGET_ESP32S3
+        help
+            GPIO number for I2C Master clock line.
+
+    config I2C_MASTER_SDA
+        int "SDA GPIO Num"
+        default 5 if IDF_TARGET_ESP32C3
+        default 18 if IDF_TARGET_ESP32 || IDF_TARGET_ESP32S2 || IDF_TARGET_ESP32S3
+        help
+            GPIO number for I2C Master data line.
+
+endmenu

examples/peripherals/i2c/i2c_simple/main/component.mk

@@ -0,0 +1,3 @@
+#
+# Main Makefile. This is basically the same as a component makefile .
+#

examples/peripherals/i2c/i2c_simple/main/i2c_simple_main.c

@@ -0,0 +1,97 @@
+/* i2c - Simple example
+
+   Simple I2C example that shows how to initialize I2C
+   as well as reading and writing from and to registers for a sensor connected over I2C.
+
+   The sensor used in this example is a MPU9250 inertial measurement unit.
+
+   For other examples please check:
+   https://github.com/espressif/esp-idf/tree/master/examples
+
+   See README.md file to get detailed usage of this example.
+
+   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 "esp_log.h"
+#include "driver/i2c.h"
+
+static const char *TAG = "i2c-simple-example";
+
+#define I2C_MASTER_SCL_IO           CONFIG_I2C_MASTER_SCL      /*!< GPIO number used for I2C master clock */
+#define I2C_MASTER_SDA_IO           CONFIG_I2C_MASTER_SDA      /*!< GPIO number used for I2C master data  */
+#define I2C_MASTER_NUM              0                          /*!< I2C master i2c port number, the number of i2c peripheral interfaces available will depend on the chip */
+#define I2C_MASTER_FREQ_HZ          400000                     /*!< I2C master clock frequency */
+#define I2C_MASTER_TX_BUF_DISABLE   0                          /*!< I2C master doesn't need buffer */
+#define I2C_MASTER_RX_BUF_DISABLE   0                          /*!< I2C master doesn't need buffer */
+#define I2C_MASTER_TIMEOUT_MS       1000
+
+#define MPU9250_SENSOR_ADDR                 0x68        /*!< Slave address of the MPU9250 sensor */
+#define MPU9250_WHO_AM_I_REG_ADDR           0x75        /*!< Register addresses of the "who am I" register */
+
+#define MPU9250_PWR_MGMT_1_REG_ADDR         0x6B        /*!< Register addresses of the power managment register */
+#define MPU9250_RESET_BIT                   7
+
+/**
+ * @brief Read a sequence of bytes from a MPU9250 sensor registers
+ */
+static esp_err_t mpu9250_register_read(uint8_t reg_addr, uint8_t *data, size_t len)
+{
+    return i2c_master_write_read_device(I2C_MASTER_NUM, MPU9250_SENSOR_ADDR, &reg_addr, 1, data, len, I2C_MASTER_TIMEOUT_MS / portTICK_RATE_MS);
+}
+
+/**
+ * @brief Write a byte to a MPU9250 sensor register
+ */
+static esp_err_t mpu9250_register_write_byte(uint8_t reg_addr, uint8_t data)
+{
+    int ret;
+    uint8_t write_buf[2] = {reg_addr, data};
+
+    ret = i2c_master_write_to_device(I2C_MASTER_NUM, MPU9250_SENSOR_ADDR, write_buf, sizeof(write_buf), I2C_MASTER_TIMEOUT_MS / portTICK_RATE_MS);
+
+    return ret;
+}
+
+/**
+ * @brief i2c master initialization
+ */
+static esp_err_t i2c_master_init(void)
+{
+    int i2c_master_port = I2C_MASTER_NUM;
+
+    i2c_config_t conf = {
+        .mode = I2C_MODE_MASTER,
+        .sda_io_num = I2C_MASTER_SDA_IO,
+        .scl_io_num = I2C_MASTER_SCL_IO,
+        .sda_pullup_en = GPIO_PULLUP_ENABLE,
+        .scl_pullup_en = GPIO_PULLUP_ENABLE,
+        .master.clk_speed = I2C_MASTER_FREQ_HZ,
+    };
+
+    i2c_param_config(i2c_master_port, &conf);
+
+    return i2c_driver_install(i2c_master_port, conf.mode, I2C_MASTER_RX_BUF_DISABLE, I2C_MASTER_TX_BUF_DISABLE, 0);
+}
+
+
+void app_main(void)
+{
+    uint8_t data[2];
+    ESP_ERROR_CHECK(i2c_master_init());
+    ESP_LOGI(TAG, "I2C initialized successfully");
+
+    /* Read the MPU9250 WHO_AM_I register, on power up the register should have the value 0x71 */
+    ESP_ERROR_CHECK(mpu9250_register_read(MPU9250_WHO_AM_I_REG_ADDR, data, 1));
+    ESP_LOGI(TAG, "WHO_AM_I = %X", data[0]);
+
+    /* Demonstrate writing by reseting the MPU9250 */
+    ESP_ERROR_CHECK(mpu9250_register_write_byte(MPU9250_PWR_MGMT_1_REG_ADDR, 1 << MPU9250_RESET_BIT));
+
+    ESP_ERROR_CHECK(i2c_driver_delete(I2C_MASTER_NUM));
+    ESP_LOGI(TAG, "I2C unitialized successfully");
+}