ESP8266 Community Forum

- Sun Sep 04, 2022 9:29 am #95217 Hi.

I bought a SGC01 garage opener which I opened and discovered an ESP inside.
I have managed to flash it with the firmware i wanted, EspHome, but I'm struggling on finding the pin to control the relay.
Have tried continuity check from COM on relay to pins on ESP without luck. Any tips?

- Sun Sep 04, 2022 11:24 pm #95218 Usually, the microcontroller pin that is used for switching the relay, is not shorted with the COM pin of the relay. If you take single-channel relay boards into consideration, you will see that the microcontroller pin is usually connected to the base of a transistor via a resistor as you can see in this diagram: https://www.researchgate.net/figure/Rel ... _341570650
There must a something like this in your board too.
So, the continuity test at the COM pin is not gonna help. You have to figure out which pin of the ESP is connected to a transistor base via a resistor.
From the photo of your board, it looks like there is an opto coupler. In that case your have to figure out which ESP pin is connected to the optocoupler's input.