PCF8754IO(4) Device Drivers Manual PCF8754IO(4)

pcf8574ioPhilips Semiconductors PCF8574 and PCF857A GPIO Controllers

pcf8574io* at iic? addr?

The pcf8574io driver provides support for the PCF8574 and PCF857A GPIO controllers. These differ only in their address on the i2c bus. System properties are used to configure the pins as LED's or sensors which are then exposed via the led(4) or envsys(4) frameworks. If any pins are configured as alert sensors, then a console message will be printed if the pin status changes.

envsys(4), iic(4), intro(4), led(4), envstat(8)

The pcf8574io driver first appeared in NetBSD 10.0.

The pcf8574io driver was written by Julian Coleman <jcoleman@netbsd.org>.

February 13, 2026 NetBSD 11.99