[Twiz O'Meter] Expansion port: technical information.

I hope this help, more than words.

This is 100% clear, thank you! Weather and time permitting, I'll build this tomorrow.

OK, I've connected it all but I have a problem (and the problem is with the relay board, I think).

When I set PIN1 to OUTPUT Active High I measure 3v3 on the expansion port, and when I set PIN1 to OUTPUT Active Low I measure 0v. This is as expected.

However, my relay board (connected to this pin) always energizes, whether it receives 3v3 or 0v on its IN pin. It probably has something to do with it expecting 5v and getting 3v3, but I've run out of time to troubleshoot. Family business is calling...

But what do you think of the situation as I've described?

PriusTwizy schrieb: OK, I've connected it all but I have a problem (and the problem is with the relay board, I think).

I suspect that your relay PCB is an "active low" type.
In this case it isn't good for ESP32, because ESP32 voltage output is 3,3v. So the pcb could read is as a low state.
You have to use an "active high". It's similar to your but without the two led.

All right, that sounds plausible. I'll test my board with an ESP32 and confirm this, and then order a correct board.

Thanks again for your help!