Using I2C in C

• I2C API
• Underlying Linux HAL

Initialization

The first step in using I2C is to configure and bring up the interface. The k_i2c_default_dev_init() function will initialize a connection with the specified I2C bus using the default configuration values.

KI2CStatus status;

status = k_i2c_default_dev_init(K_I2C1);
if (status != I2C_OK)
{
    fprintf(stderr, "Failed to initialize I2C bus connection: %d\n", status);
    return -1;
}

Writing

The k_i2c_write() function should be used to write to an I2C device. The function takes four arguments:

• The I2C bus to use for communication
• The I2C address of the slave device
• A pointer to the data to be written
• The number of bytes to be written

The function returns a KI2CStatus value. I2C_OK indicates that the function completed successfully.

KI2CStatus status;
char cmd = 0x40;
int slave_addr = 0x80;

status = k_i2c_write(K_I2C1, slave_addr, &cmd, 1);
if (status != I2C_OK)
{
    fprintf(stderr, "Failed to write to I2C device: %d\n", status);
    return -1;
}

Reading

The k_i2c_read() function should be used to read data from an I2C device. The function takes four arguments:

• The I2C bus to use for communication
• The I2C address of the slave device
• A pointer to the read buffer
• The number of bytes to be read

The function returns a KI2CStatus value. I2C_OK indicates that the function completed successfully.

KI2CStatus status;
char buffer[100];
int slave_addr = 0x80;

status = k_i2c_read(K_I2C1, slave_addr, buffer, 10);
if (status != I2C_OK)
{
    fprintf(stderr, "Failed to read from I2C device: %d\n", status);
    return -1;
}

Termination

Once all I2C work has been completed, the k_i2c_terminate() function should be used to close the connection with the I2C bus and perform system cleanup.

k_i2c_terminate(K_I2C1);