| OWC(4) | Device Drivers Manual | OWC(4) |
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:
gpiobus you are attaching to.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).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.
| June 26, 2019 | Debian |