Relay activation via physical button using an MCP23017

[PeteKnight]

@Diego_La_Mattina, I’ve now bought a couple of these MCP23017 and spent some time figuring out how they work.
I’ve written it all up here, although it is a bit of a long read!..

Using the MCP23017 IO Expansion Board

EDIT NOVEMBER 2021… Anyone interested in controlling multiple relays may also want to take a look at this topic, which uses a pre-built 16-way relay board and 2x 74hc595 shift registers: https://community.blynk.cc/t/esp8266-16-way-relay-board-using-2x-74hc595-controllers/57689?u=peteknight END OF EDIT . I had a project recently where I wanted to use 5 physical buttons, with built-in LED indicators, to control 5 relays. That meant having 15 GPIOs available, so I built the project around an E…

Pete.