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PCF8574(4) FreeBSD Kernel Interfaces Manual PCF8574(4)
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:
device pcf8574
device gpio
device iicbus
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.
FreeBSD 14.0-RELEASE-p6 November 6, 2021 FreeBSD 14.0-RELEASE-p6