I am using I2C on the Snowball board, running at 400KHz by default.
I use the api defined in <linux/i2c.h>
and configure as follows
m_fd = open(m_filename.c_str(), O_RDWR);
if (ioctl(m_fd, I2C_SLAVE_FORCE, m_addr) < 0)
{
throw I2cError(DeviceConfigFail);
}
How can I change the speed to standard mode (reduce clock rate to 100KHz)?
You can change the I2C SCL frequency in your driver's 'struct i2c_gpio_platform_data'.
static struct i2c_gpio_platform_data xyz_i2c_gpio_data = {
.sda_pin = GPIO_XYZ_SDA,
.scl_pin = GPIO_XYZ_SCL,
.udelay = 5, //@udelay: signal toggle delay. SCL frequency is (500 / udelay) kHz
....
};
Changing 'udelay' changes your 'xyz' i2c device's clock frequency.