Looking for an app... an ideas?

I need to communicate wirelessly between the stage and sound booth for a weekly production. I was thinking that we could just flash LEDs on and off w/ a momentary on/off button and the number of flashes (or a system similar to morse code) would tell the problem/instruction (i.e. 2 flashes/1 long 1 short/etc would mean "Microphone 1 up".) This is easier than text b/c you don't have to navigate a keyboard and it's also more discreet.

However, is there just an app for this or an app that could be recommissioned for this?

Thanks,

Zach