https://github.com/tuupola/esp_software_i2c

Software I2C driver for ESP-IDF (ESP32)
https://github.com/tuupola/esp_software_i2c

Last synced: about 2 months ago
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Software I2C driver for ESP-IDF (ESP32)

• Host: GitHub
• URL: https://github.com/tuupola/esp_software_i2c
• Owner: tuupola
• License: mit
• Created: 2018-04-21T09:05:47.000Z (over 6 years ago)
• Default Branch: master
• Last Pushed: 2019-09-21T17:03:06.000Z (over 5 years ago)
• Last Synced: 2024-10-11T22:44:48.910Z (2 months ago)
• Language: C
• Homepage: https://appelsiini.net/
• Size: 6.84 KB
• Stars: 22
• Watchers: 4
• Forks: 8
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE.txt

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README

        
#  Software I2C master for ESP-IDF (ESP32)

## What?

ESP32 has only two hardware I2C ports. Sometimes you are already using both ports for I2C slaves but still need to have an I2C master. Bitbanging to the rescue!

## Install

Install the library using by cloning it to the `components` folder of your ESP-IDF project.

``` bash

$ cd components

$ git clone [email protected]:tuupola/esp-software-i2c.git

```

## Usage

Software driver API mimics the original [ESP-IDF hardware master API](https://esp-idf.readthedocs.io/en/latest/api-reference/peripherals/i2c.html#i2c-api-master-mode). Biggest difference is that there is no [command link](https://esp-idf.readthedocs.io/en/latest/api-reference/peripherals/i2c.html#_CPPv219i2c_cmd_link_createv) and instead of queuing commands are sent directly to the I2C bus. Example below reads `SLAVE_DATA_LENGTH` bytes from `SLAVE_ADDRESS` and dumps it to console. See [tuupola/esp-examples](https://github.com/tuupola/esp-examples/tree/master/008-i2c-sw-master) for better example.

```c

static const char *TAG = "sofware_i2c";

uint8_t *data_read = (uint8_t *) malloc(SLAVE_DATA_LENGTH);

sw_i2c_master_start();

sw_i2c_master_write_byte((SLAVE_ADDRESS << 1) | I2C_MASTER_READ);

if (SLAVE_DATA_LENGTH > 1) {

    sw_i2c_master_read(data_read, SLAVE_DATA_LENGTH - 1, ACK);

}

sw_i2c_master_read_byte(data_read + SLAVE_DATA_LENGTH - 1, NAK)

sw_i2c_master_stop();

ESP_LOG_BUFFER_HEXDUMP(TAG, data_read, SLAVE_DATA_LENGTH, ESP_LOG_INFO);}

```

Same code with the original ESP-IDF hardware API would be.

```c

static const char *TAG = "hardware_i2c";

uint8_t *data_read = (uint8_t *) malloc(SLAVE_DATA_LENGTH);

i2c_cmd_handle_t cmd = i2c_cmd_link_create();

i2c_master_start(cmd);

i2c_master_write_byte(cmd, (SLAVE_ADDRESS << 1) | I2C_MASTER_READ, ACK_CHECK_ENABLE);

if (SLAVE_DATA_LENGTH > 1) {

    i2c_master_read(cmd, data_read, SLAVE_DATA_LENGTH - 1, ACK);

}

i2c_master_read_byte(cmd, data_read + SLAVE_DATA_LENGTH - 1, NAK)

i2c_master_stop(cmd);

i2c_master_cmd_begin(I2C_MASTER_NUM, cmd, 1000 / portTICK_RATE_MS);

i2c_cmd_link_delete(cmd);

ESP_LOG_BUFFER_HEXDUMP(TAG, data_read, SLAVE_DATA_LENGTH, ESP_LOG_INFO);

```

## License

The MIT License (MIT). Please see [License File](LICENSE.txt) for more information.