Killing It (Safely): Our ASV’s Kill Switch Board Gets An Upgrade

October 2025

How The Boards Works:

Our ASV features a remote-controlled Emergency Stop (E-Stop) switch for safety. The FlySky FS-i6 controller sends Pulse Width Modulation (PWM) signals to a custom PCB that converts the signal into a proportional direct current (DC) voltage. This conversion is necessary to control a 12V relay that powers the thrusters. The PCB uses an operational amplifier to process the PWM signal, and a voltage comparator compares the resulting DC voltage to a reference voltage. If the voltage drops below the threshold, the relay opens, cutting power to the thrusters and ensuring the ASV can be safely stopped. For a more in-depth description of the circuit operation, see our blog post from the first revision of this board: here!

What We Improved:

Since this PCB’s creation there were several improvements identified and the team decided to respin the PCB in preparation for RoboBoat 2026. A fuse was added to the PCB as a safety feature to protect the system from short circuits and potential damage. An LED was also included to help with debugging by indicating whether the board was receiving power. Additionally, the team chose to replace the original push-button terminal blocks with screw terminal blocks, which had proven easier to work with in other parts of the system. A previously missing trace on the 12V rail, a detail missed during prior fabrication, has now been fixed as well. Finally, for a personal touch, the updated board now features the Iceberg ASV logo on the silkscreen!