As previously mentioned, Two pieces of software are required, one to run on the Feather, one on the (remote) Raspberry Pi running a Python program to monitor and control the Feather using UDP over wifi. The Python program runs a Tkinter GUI.
The Python program looks like the screen shot on the left (although this is actually running on a PC).
This is a development of a program I have been using for about a year now. By clicking on the top right button, you can step through the various Arduinos and Feathers I am using to control things round the house.
Clicking on the buttons in a group of four near the middle bottom turns the relays controlled by the Feather’s port expander, on and off. Green is off, yellow/orange is on. The buttons only become operative when the relevant Feather and expander is selected
The Python program can be found here and the Feather program here.
These programs are currently in a developmental, testing phase. In particular, the Feather program does nothing other than control the expander chip and is running on a breadboard similar to the setup shown on the last page.