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
gpio(4),
iic(4),
intro(4)
HISTORY
The
gpioiic driver first appeared in
OpenBSD
3.9 and
NetBSD 5.0.
AUTHORS
The
gpioiic driver was written by
Alexander
Yurchenko
<
grange@openbsd.org>
and was ported to
NetBSD by
Marc
Balmer
<
marc@msys.ch>.
CAVEATS
A
gpioiic device can not be detached from the
gpio(4) bus at runtime due to the
fact that
iic(4) busses can not
detach once attached.