Beyond the Arena: Our PCBs

The Electronics Behind the Robot

Without a reliable electrical system, none of our robots were going to go anywhere. For DD Robocon 2026, our robots relied on a modular set of custom PCBs that handled everything from sensors and encoders to motors, servos, and power distribution. And here is exactly what we made.

The Interface Board

At the heart of our electronics system are two Teensy microcontrollers. We chose to use two instead of trying to make one controller handle everything, giving us some much-needed surplus pins and dividing the workload between them. The two Teensy communicate with each other through Ethernet. One handles our sensors and servos, while the other works with the motor driver ICs that control our planetary DC motors and other actuators. The interface board is a four-layer PCB that connects these systems together. It receives power from the actuator board through an XT30 connector and distributes it to the other components on the board. We designed separate 5V and 3.3V power rails using buck converters. The 3.3V supply powers components such as the BNO, I2C devices, motor-related electronics, and encoders, while the 5V supply handles components that need the higher voltage like teensy, distance sensors and deadwheels. We also use logic level converters to allow our Teensy to communicate safely with 5V sensors such as the ultrasonic sensors and deadwheels. The Teensy themselves have dedicated buck converters, keeping their power supply separate from the rest of the system.

The Actuator Board

While the interface board manages the robot's electronics and communication, the actuator board deals with the parts that actually make things move. The board provides ten motor outputs and can control up to eight servos. It contains four relays for control – DCV for pneumatics , along with ten fuses, with each motor receiving its own dedicated fuse. Everything is plug and play. To accomplish this we used XT30 connectors for the motors and XT60 for the main battery supply and switch. Each motor’s XT30 connector has 2 tactile switches next to it. These switches allow the monitor to rotate in either direction at maximum voltage. This serves two purposes: setting motors at a position and for debugging purposes. We also have separate buck converters for the different parts of the circuit. A 3.3V supply enables the motor drivers, while a 5V supply powers the relays. The board receives power from the battery through a switch and provides multiple outputs for the rest of the robot. It also has dedicated inputs for powering our Nvidia Jetson and for hot-swapping batteries.

Making Things Plug and Play

One of our biggest priorities was reducing the amount of loose wiring inside the robot. Instead of relying heavily on screw terminals or solder joins, we used RMC headers, to connect sensors, encoders, and other components. Some of these connectors are also used for limit switches and CAN or UART communication. This made the system much more modular. If a component stopped working, we could disconnect it and replace it without having to dismantle an entire section of the robot. The interface board plugs into the actuator board through a set of header pins. This allows the common actuator board to be controlled by different interface boards. This is especially useful as each interface board caters to a different set of sensors or microcontrollers. The motor driver sides of our PCBs resemble last year’s PCB closely.Sensors and number of actuators vary vastly depending on the competition’s need each year. We can create a new interface board by controlling the amount of actuators needed on the actuator board while leaving the other pins for sensors and communication intact. This modular design of interface and actuator boards allows reusability of PCBs and customization of any number of Teensy or other microcontrollers to control the actuator board. Currently 2 types of interface boards are designed: a dual teensy and a single teensy version. An upgrade from last year is the use of smaller XT30 and MR30 connectors. Additionally, mini blade fuses have been incorporated to allow for a compact PCB. We also added resistors where necessary for power regulation and LEDs to give us a quick visual indication of whether different parts of the board were receiving power. While debugging, knowing that a circuit is actually receiving power without reaching for a multimeter saved us hours.

The robot’s own GMap

Our robots also use rotary encoders connected to dead wheels. By measuring how much these wheels rotate, the encoders let us estimate how far the robot has travelled. With multiple dead wheels, we can also estimate changes in the robot's orientation. This is called odometry, and it gives the robot a way to keep track of its movement without relying entirely on external references. It was our robot’s personal Google Maps.

Keeping the Robot Running

Hot-swapping was particularly important for us. Imagine the robot is in the middle of a match and its battery is running low. Simply switching batteries would mean turning off the entire system, including the Jetson. So that would never work for us. Our solution was to allow a new battery to be connected before the old one is removed. This means the system can transition between batteries without shutting down. The actuator board also uses electrolytic and decoupling capacitors to help keep the power supply stable, along with the necessary resistors.

Our Mis-steps

Designing a PCB is a process of iteration, and ours was no exception. Our interface board taught us a lot. One of our biggest practical issues was the Ethernet connection. We had not left enough space for the Ethernet header pins, so we had to improvise and create custom connections using ribbon cables and custom-made headers. Another mistake involved the USB power connection. We initially supplied the USB port directly from the 5V buck converter. We later realised that the USB and Teensy systems shared a common ground, and it would be more efficient and appropriate for the 5V supply to pass through the Teensy instead. The actuator board had its own lessons. The main switch became difficult to access once the bot was assembled, the board got covered, curbing our access to it. We also realised that having a single fuse for 4 sets of servos was not the most efficient protection strategy. We also identified the absence of a dedicated fuse at the main battery input as something that should be improved in a future iteration. None of these mistakes were wasted. Every one of them gave us something to change, document, and carry forward.

Building to Be Better

Once the boards were assembled and tested, we finished them with conformal coating to provide additional protection against environmental conditions. Together, the two interface boards, two actuator boards, and the rest of our electronics formed the electrical backbone of our robots. More importantly, they represented the way we approached the problem. We did not just want a PCB that worked. We wanted a system that could be understood, debugged, replaced, and improved. The interface boards were developed by Abdullah and Vrashni, while the actuator boards were developed by Vineet and Nilesh. A robot might look like one machine from the outside. Inside, it is a collection of hundreds of decisions, connections, and compromises that all have to work together. And sometimes, when they don't, you learn exactly what to do better next time. This is what we learned while building the electronics for DD Robocon 2026.