How to Build a Remote Kill Switch
VCU Parts List
The Beefcake Relay can be seen next to the larger, blue, 24V/80A relay. The VCU itself (the Pro Mini connected to the RFM69 breakout board) can be seen in the lower right corner.
Parts used on the Vehicle Control Unit:
- Arduino Pro Mini 328 - 3.3V/8MHz
- RFM69 Breakout
- Beefcake Relay Control Kit
- 24VDC 80A Relay
- 48V to 24V DC to DC Buck Converter
- 48V to 5V DC to DC Buck Converter
- A handful of 3-Pin and 2-pin JST Jumper Wire Assemblies
I use our SparkFun RFM69 Breakout for a variety of reasons:
- Encryption: This allows me to rest easy that no one else (ok I’m sure someone could hack it) will power up/down my car.
- Software Defined Radio: The AVC has nearly 100 teams, all with their own radios and telemetry systems. It’s excellent to be able to sit in the 434MHz or 915MHz spectrum rather than the very crowded 2.4GHz arena.
- Data Rate Scaling: The data rates can be reduced and frequency changed so that range can be increased quite significantly. UKHASnet has even setup a network of RFM69 based repeaters across Europe with transmission ranges pushing 65km (40miles)! I plan to be within sight of my autonomous power wheels at all times, but it’s good to know the 100mW transmission power of the RFM69 can do the job.
- Library Support: The community has been writing various libraries to support the RFM type modules for years now. The latest I use for this project is RadioHead by AirSpayce. It does everything I need with some decent documentation to boot.