Adding a Port Extender MCP23017 to the MLC Mini

I’m running a MLC mini for a switch (actually running two MLC minis on a double crossover) and I need a total of 16 light outputs. If I put a MCP23017 on one of the the minis I can get the desired number of signal lights for the double crossover. My question is where do I connect the 23017 on the mini? D1 and D2 on the ESP is wired for the sensors but, there are 3 unused pins (SC, SD SK) that I am hoping that can be used. Has anyone attempted this? Photo Here

• This topic was modified 6 months, 1 week ago by Steven Elston.