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 15.1 November 6, 2021 PCF8574(4)
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