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esp32-I2Cbus

★ 29 Open GitHub ↗

ESP32 I2C master library for esp-idf

// repository documentation

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# **I2Cbus**

I2C interface library in C++ for working with **Espressif ESP32 IoT Development Framework _(esp-idf)_**, that supports master mode.

The intention of this library is to read and write to I2C slave devices (most sensors) with ease, by providing quick and specific functions aimed for 8-bit data. It is based on I2Cdev by Jeff Rowberg.

## Install

You can clone it right into your project components directory or in your specific library path.

```git
 git clone https://github.com/natanaeljr/esp32-I2Cbus.git I2Cbus
```

## Usage

The ESP32 has two I2C controllers which can control two separated buses, so the library provides two ready-to-use objects:

`i2c0` which corresponds to the I2C controller port 0, and

`i2c1` which corresponds to the I2C controller port 1.

However you can create your own object as you wish.

### Example

```C++
// default objects
i2c0.begin(GPIO_NUM_16, GPIO_NUM_17);  // sda, scl, default clock 100 Khz
i2c1.begin(GPIO_NUM_21, GPIO_NUM_22, 400000);  // sda, scl, 400 Khz
// OR create an object which manages controller num 0
I2C_t myI2C(I2C_NUM_0);
// configure and initialize
myI2C.begin(GPIO_NUM_21, GPIO_NUM_22);
myI2C.setTimeout(10);  // default was 1000ms
// start using
myI2C.scanner();
myI2C.writeByte(DEVICE_ADDR, REG_ADDR, DATA);
myI2C.readBytes(DEVICE_ADDR, REG_ADDR, LENGTH, BUFFER);
myI2C.close();
```

### List of methods

```C++
// SETUP
esp_err_t begin(gpio_num_t sda_io_num, gpio_num_t scl_io_num, uint32_t clk_speed = I2CBUS_CLOCKSPEED_DEFAULT);
esp_err_t begin(gpio_num_t sda_io_num, gpio_num_t scl_io_num, gpio_pullup_t sda_pullup_en, gpio_pullup_t scl_pullup_en, uint32_t clk_speed = I2CBUS_CLOCKSPEED_DEFAULT);
esp_err_t close();
void setTimeout(uint32_t ms);

// WRITING
esp_err_t writeBit(uint8_t devAddr, uint8_t regAddr, uint8_t bitNum, uint8_t data, int32_t timeout = -1);
esp_err_t writeBits(uint8_t devAddr, uint8_t regAddr, uint8_t bitStart, uint8_t length, uint8_t data, int32_t timeout = -1);
esp_err_t writeByte(uint8_t devAddr, uint8_t regAddr, uint8_t data, int32_t timeout = -1);
esp_err_t writeBytes(uint8_t devAddr, uint8_t regAddr, size_t length, const uint8_t *data, int32_t timeout = -1);

// READING
esp_err_t readBit(uint8_t devAddr, uint8_t regAddr, uint8_t bitNum, uint8_t *data, int32_t timeout = -1);
esp_err_t readBits(uint8_t devAddr, uint8_t regAddr, uint8_t bitStart, uint8_t length, uint8_t *data, int32_t timeout = -1);
esp_err_t readByte(uint8_t devAddr, uint8_t regAddr, uint8_t *data, int32_t timeout = -1);
esp_err_t readBytes(uint8_t devAddr, uint8_t regAddr, size_t length, uint8_t *data, int32_t timeout = -1);

// TOOLS
esp_err_t testConnection(uint8_t devAddr, int32_t timeout = -1);
void scanner();
```

Each method have an optional custom timeout for that specific call, if this value is not passed (default `-1`) or is `< 0`, it will use the default timeout. You can change the default timeout by calling `setTimeout(ms)`.

@see header file for more notes and descriptions.

## Menuconfig

You can change some settings (for debugging) in menuconfig under components and I2Cbus.

![menuconfig-I2Cbus](https://raw.githubusercontent.com/natanaeljr/gh-assets/master/I2Cbus-esp32/menuconfig1.png "Menuconfig I2Cbus")

---

See also: SPIbus library https://github.com/natanaeljr/esp32-SPIbus

esp32-I2Cbus

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