While the board partly serves to route signals without using messy external wires, some of our devices require additional filtering or signal conversion.
The signal board contains three SP3232EB ICs to translate serial RS232 signals from devices into TTL signals for our companion computer.
We also use a number of N-Channel MOSFETs to amplify 3.3V PWM signals from the flight computer to 5V signals for the servos.
One of the main challenges faced was interference and noise on the CAN bus: the bus in which both our motor controllers communicate with the flight computer.
This was partly solved in testing by shifting the location of the high-voltage power cables, but it was a problem we aimed to tackle on the second version of the Signal Board.
We tested out different filter configurations with 0.1μF capacitors and 11μH common mode chokes on bread-boards. While we had success with these filters, we still wanted the ability to swap out different filters on the new version of the Signal Board.
That’s when we had the idea of creating modular boards with different filters that plug into our Signal Board and allow us to alter the filters we use on the CAN bus.
These modular boards are similar to the shields you can buy for Arduinos, as you simply stack them on top of the Signal PCB.