This project implements a wireless intercom system using the RFM12B radio module and the Atmega 328P microcontroller running the Arduino environment.
I wanted a wireless intercom so I could stop shouting up the stairs at the kids.
The consensus on the web was that the RFM12B is not suitable for speech: challenge!
Implements a five-station intercom with the following features:
- Call each station individually (station to station)
- Call all stations together (broadcast)
- LED indicates which station is calling
- Uses low power sleep modes when not in use giving up to 3 months life on a PP3 battery
- Atmega 328P running at 16MHz
- Microphone AGC circuit
- 8-bit audio sampled at 8kHz
- RFM12B running at 115kBaud
- Range in excess of 20m (depends on length of aerial)
The circuit design is fine and works well, but:
- Battery life could be better - the RFM12B is a bit of a hog. Use a 9V wall-wart if you're bothered.
- The PCB layout sucks. Sorry. If I had time I'd do it again using SMD parts, and I'd probably use a more modern, lower power replacement for the RFM12B.
Relies on my RFM12B library - a non-blocking, event-driven implementation. Get it here: