can I use the same approach for Waveshare Relay?
this is the docs: http://www.waveshare.com/wiki/RPi_Relay_Board
which pins would work with relay switch 1,2,3? it should work with changing high/low voltage, right?
Hello @hadi.farnoud, welcome to the Cayenne Community.
You won’t be able to use the Cayenne GPIO tab to interact with extensions like this Waveshare board unless they are explicitly listed in our supported Pi GPIO extensions list.
You can however connect your Pi via our MQTT API. This way, you can interact with any of the pins/relays on the expansion board because the MQTT client is just sending and receiving values on virtual MQTT Channels, and you can handle interaction with the extension board with Python code provided by the manufacturer (like what is in the wiki you linked).
Waveshare relay support