stemmo 0 Posted January 11, 2021 (edited) Hi all, I need to connect in the simplest mode a GPIO pin (as INPUT) to the contact of a relay (not the control pins of the replay) that connects the pin to the GND. Of course I'm using the internal pull-up resistor but I don't know the value of this one. Is it a problem to connect the pin directly to GND or better to use a resistor to limit? Value? Thanks a lot! Regards Edited January 11, 2021 by stemmo Share this post Link to post Share on other sites
maartinus 0 Posted April 30, 2021 Hi, you should use 2 resistors. The first one (10K) connected to 3.3V (yellow pin) and GPIO input and second one (1K) connecting GPIO input and relay contact. Share this post Link to post Share on other sites