Arduino write I2C command to turn on one relay

Software Arduino
1

Hello,

I use an Arduino UNO to toggle relays on your board: 32-Channel High-Power Relay Controller with I2C Interface. My code works, see an example here, but I have to write to all 16 relays at a time. How can I write to just one relay with an Arduino over I2C? Can you help me figure this out please?

Thank you.

2

Hi, Unfortunately its not possible as the commands the chip expects are limited to bank level commands so you can only target groups of 8 relays at a time at a minimum.

You can write methods to abstract the process like we did over here: https://github.com/ncd-io/MCP23017/blob/master/Particle/MCP23017.cpp where we use the current bank status to compare the bit that controls the desired relay.

1 Like
3

OK. Thank you Jacob!