owc —
Dallas
Semiconductor 1-Wire Controller
device owc
The
owc module implements Dallas Semiconductor
1-Wire signaling. It attaches the
ow(4) driver
1-Wire bus protocol. The
owc device implements
the Link Layer of the 1-Wire bus protocol stack.
Bit banging a pin on a
gpiobus(4) is the only
supported controller. Both standard and overdrive transfer timings are
implemented. Strong pull-up functionality needed to support parasitic mode is
not implemented.
To enable 1-Wire for FDT systems requires modifying the DTS for your board to
add something like:
/ {
...
onewire {
compatible = "w1-gpio";
gpios = <&gpio 4 1>;
};
...
};
The gpios property describes the GPIO pin the 1-Wire bus is connected to. For
more details about the
gpios property, please
consult
/usr/src/sys/dts/bindings-gpio.txt.
On a
device.hints(5) based system these values are
required for the
owc:
- hint.owc.%d.at
- The gpiobus you are attaching
to.
- hint.owc.%d.pins
- This is a bitmask that defines a pin on the
gpiobus that is to be used for the 1-Wire
bus. For instance, to configure pin 10, use the bitmask of 0x400. Please
note that this mask should have only one bit set (any other bits - i.e.,
pins - will be ignored).
gpiobus(4),
ow(4),
ow_temp(4),
owll(9),
own(9)
1-Wire is a registered trademark of Maxim Integrated Products, Inc.
The
owc driver first appeared in
FreeBSD 11.0.
The
owc device driver and this manual page were
written by
Warner Losh.
The gpio driver implements timing by busy waiting, which can cause a high load
on slower systems.
Overdrive mode has not actually been tested.