GPIOIIC(4) - Device Drivers Manual #
GPIOIIC(4) - Device Drivers Manual
NAME #
gpioiic - GPIO I2C controller
SYNOPSIS #
gpioiic* at gpio? offset 0 mask 0x3 flag 0x0 gpioiic* at gpio? iic* at gpioiic?
DESCRIPTION #
The gpioiic driver allows bit-banging an I2C bus as a master using two GPIO pins. By default the first pin is used as a serial data (SDA) signal and the second as a serial clock (SCL). If the flag locator is set to 0x01, the order of the SDA and SCL signals is reversed. 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.
SEE ALSO #
HISTORY #
The gpioiic driver first appeared in OpenBSD 3.9.
AUTHORS #
The gpioiic driver was written by Alexander Yurchenko <grange@openbsd.org>.
OpenBSD 7.5 - July 16, 2013