Manual browser: gpioow(4)

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


The gpioow driver first appeared in OpenBSD 4.0 and NetBSD 4.0.


The gpioow driver was written by Alexander Yurchenko <> and was ported to NetBSD by Jeff Rizzo <>.
July 19, 2009 NetBSD 7.0