I2C control of pcf8574

I am using a BTT SKR 1.4 Turbo board which has limited additional I/O pins and i would like to use an I2C expander based on the pcf8574 chip to control basic on / off functions.

I have the board working with wires.h with a arduino nano without any issues.

Can anyone help with pointers to where and how in the Marlin firmware i can define the addtional 8 pins and allow Marlin to control them, so i can use them in a pins file.

thanks

take a read of [reprap.org]
where I went through the steps of adding a pca9685 IO expander.

but this was pre v2... With HAL's its my be easier to "add pins" transparently.

Edited 1 time(s). Last edit at 03/01/2020 09:47PM by Dust.