for this project is to helps the blind people in making a call. Each key when pressed produce a audio sound of the number pressed. To confirm the digits pressed is correct an additional key should repeat all the digits pressed in audio. Can anyone give me any information or comment on this project?? Anything to intro or any books in order for me to do this project?? do u guy think is hard?? I dont even know where to start, i cannot find a circuit diagram of it..