I have an upcoming project which requires me to use about 8 different Arduinos, probably more. They all perform a light show which turns off and on various LEDs at different timings to simulate a "light dance". All that is taken care of, however these Arduinos will be at different locations and they need to communicate wirelessly.
My plan is to have only a master Arduino and the rest of them be slaves. I would like to send a simple "start" message from a phone or other device to the master Arduino, and this master Arduino to send the message to the rest in order to start the show. They all need to start at the same time.
The problem is that I don't know how to achieve this. I have enough transceivers and I think this might be the right direction to take but I am still unsure on how to send the signal from the phone to the master Arduino.
I am a programmer and have very basic knowledge of circuits, so detailed explanation would be appreciated.
Best Answer
If you're willing to sacrifice a cheap phone, take a tip from terrorists all over the world: the ring signal in a cell phone can be detected easily and used to power all sorts of useful detectors.
Open up a cell phone and find the two leads that connect to the ringer. Route these to the master Arduino, and have it detect a signal on the lines. You might need to do a little investigation to find out exactly what the signal looks like, but that ought to be straightforward.