ChessLR progress report 4. I got two MCP23017 port expanders working on my Raspberry Pi. The chip refused to work until I eventually figured out that the negative rail on my breadboard wasn't connected. While searching for a reason it didn't work lead me to a site with examples of how to use the command line to test the I2C bus for connected devices, as well as be able to send data to it.
Copyright © 2020, Lee Patterson