at the moment i have and arduino mega 2560 and im using it to try to control the light switchs at home, atm i have an encoder, an RF transmitter connected to the arduino, and a individual board with a decoder, RF receiver and a relay to change the state of the light switch, so far so good, now im facing a problem...
I want to know the true state of the light, cause at the moment, if i turn on the light using the board and then turn off the light using the switch, on the software i get that the light is still on but in reality it is off.
i've been told that i could use an opto-coupler so i can know if its on or not, but i need to find a way to transmit it to the arduino. the size of the board is a problem, i need it to be the smaller as possible.
I've thought about a board with a micro-controller, an opto coupler and the nRF24L01+, something like this
You think this is doable? will it be big? im planning on having this around the house, so we're talking about quite a few (around 14)