NAME

pcf8574 — driver for the PCF8574 8-bit I2C IO expander

SYNOPSIS

To compile this driver into the kernel, place the following lines in your kernel configuration file:

Alternatively, to load the driver as a module at boot time, place the following line in loader.conf(5):

pcf8574_load="YES"

DESCRIPTION

The pcf8574 driver provides gpiobus(4) control over 8 GPIO pins. The pins are quasi-bidirectional. Only low output can be actively driven. High output is equivalent to input.

On an FDT(4) based system the following properties must be set:

compatible

Must be set to "nxp,pcf8574".

reg

The I2C address of pcf8574.

The DTS part for a pcf8574 device usually looks like:

/ {

	...
	pcf8574@27 {
		compatible = "nxp,pcf8574";
		reg = <0x27>;
	};
};

SEE ALSO

fdt(4), gpiobus(4), iicbus(4)

HISTORY

The pcf8574 driver and this manual page was written by Andriy Gapon <avg@FreeBSD.org>.

BUGS

The pcf8574 driver does not support the input change interrupt that the hardware provides.