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GPIOOW(4) Device Drivers Manual GPIOOW(4)

gpioow1-Wire bus bit-banging through GPIO pin

gpioow* at gpio? offset 0 mask 0x1
gpioow* at gpio?
onewire* at gpioow?

The gpioow driver allows bit-banging a 1-Wire bus as a master using one GPIO pin. The pin is used as a data signal. The GPIO pin must be able to drive an output and read an input.

The pin number can be specified in the kernel configuration with the offset locator. The mask locator should always be 0x1 in this case. The offset and mask can also be specified when gpioow is attached at runtime using the GPIOATTACH ioctl(2) on the gpio(4) device.

gpio(4), intro(4), onewire(4)

The gpioow driver first appeared in OpenBSD 4.0.

The gpioow driver was written by Alexander Yurchenko <>.

July 16, 2013 OpenBSD-5.5