The use of the low-cost RFM12 868 MHz (US: 915 MHz) ISM (licence-free) radio module with microcontrollers like the ATmega and the R8C13 is straightforward once you’ve read some relevant Elektor publications. Here, the use of the RFM12-434-D DIP type transceiver module for 434 MHz (US: 315 MHz) [4] is proposed instead of the RFM12-868-S, which is an SMD type. Of course, the antenna length has to be changed to 17 cm to suit the lower frequency.