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PCF8574(4)		     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 ports 15.1		November 6, 2021		      PCF8574(4)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=pcf8574&sektion=4&manpath=FreeBSD+15.1-RELEASE+and+Ports>

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