I have a little keyfob style remote that I want to mod. It runs on a 3 volt button cell. I want to control the three switches with an ESP8266. The switches are connected to ground, and directly to a package without any identification on it. I figure it has a pull up resistor internally. The voltage on the input pin is 3.00 volt. The output of the microcontroller is 3.3 volt.
I'm not keen on soldering 3 extra transistors to the contraption, if I can help it.
If I were to connect a gpio pin directly to the input pin of the mystery package, will the backwards current break it? If I were to power the entire board with 3.3 volt, would that allow me to forego the transistors? It's a shame I cannot identify the package, but would those extra .3 volts usually pose a problem to IC's? I reckon it makes a difference that this board has an rf circuit on it.