The
gpioiic driver allows bit-banging an I2C bus as a master using two GPIO pins. The first pin is used as a serial data (SDA) signal and the second as a serial clock (SCL). Both GPIO pins must be able to drive an output and the SDA pin must be also able to read an input.
The pins can be specified in the kernel configuration with the
offset and the
mask locators. The
offset and
mask can also be specified when
gpioiic is attached at runtime using the
GPIOATTACH ioctl(2) on the
gpio(4) device. Each bit in the
mask locator defines one pin; the pin number is calculated as an addition of the bit position and the
offset locator. For example,
offset 17 and
mask 0x5 defines pin numbers 17 and 19.