Max simultaneous key presses for Keyboard library

I am currently designing a SNES to USB adaptor for my RetroPie (http://blog.petrockblock.com/forums/forum/retropie-project-forum/emulators/) system. The question that I have is how many simultaneous keypresses can the library handle? I have been searching but not found and figure, just instructions on how to use it. I know that the Teensy can do 6, however I was hoping to be looking at at least 12 preferably 16, as that is the maximum number of buttons that can be pressed simultaneously on two SNES controllers. I could just use 2 Arduinos but that seems silly when one should be more than able to deal with 2.

Any help or suggestions would be greatly received!

Instead of using the keyboard library, why not just adapt the SNES controller library? It reads each button as a bit and stores it into two bytes. This allows all the buttons to be pressed, but I'm not sure if it can distinguish multiple controllers. That you may need to look into.

Thanks for the reply :slight_smile:

Sorry I wasn’t too clear on my meaning :blush: I am going to use the SNES library to control the SNES controller but I want the Arduino to act like a keyboard for the raspberrypi. So that when a button is pressed on the controller the RPi sees the corresponding keyboard key for that action.

Not sure I have made that any clearer! I want to be sure before I order any parts.

First, you will need to get an Arduino Leonardo as it can act as a functional keyboard. Second, I don't know how many simultaneous key presses it can record, in fact I don't think it even sends out simultaneous key presses at all. From what I read, it sends the key presses one key at a time, so it's possible it can send any amount of key presses. However I don't have an Arduino Leonardo myself , so I can't do any tests to confirm this. Maybe another member can do a test and share the results.