did you ever runned out of io pins? Than is here the solution.
Step 1: Part List
you only need a arduino and a mcp23017 (ebay)
Step 2: Watch the Video
watch this video!
Step 3: Upload the Code
Upload this code(put them all in one map)
Step 4: Subscribe
don't forget to subscribe to TechMaker
Eric Brouwer made it!