Custom Microcontroller

A custom Teensy-based microcontroller which will control all Revision B boards for the 2025 CU Hyperloop tunnel boring machine

Schematic for microcontroller and early WIP layout

For all previous years of CU Hyperloop, our boards have used the Teensy 4.1 microcontroller. The Teensy 4.1 is cheap, fast (600MHz), has an ethernet transceiver, and numerous analog and PWM pins, among a host of other benefits for our applications. If the Teensy is so good, why did we decide to make a new one? Well, there were a few improvements I thought I could make: vertical ethernet connector mounted directly on the microcontroller, vertical usb, CAN pins, remove the SD card, remove unnecessary pins, and of course give me great engineering experience. These changes would make the Teensy even smaller, while making integration easier with vertical components, and getting rid of components we don't need.

Another crucial requirement for the microcontroller was complete compatibility with 2025 Revision A boards that will use the Teensy 4.1. If we had to change a large portion of code and schematic to be able to work with the custom mcu, it would not be worth all the extra time spent. Therefore, the custom mcu uses the Teensy 4.1 bootloader, and has the same pinout as the Teensy 4.1 (without some pins at the bottom). This will make integration with Revision B or C boards much quicker and easier.

The final mcu will use the same 600MHz arm processor as the Teensy 4.1, and include the following capabilities: 3 CAN bus (1 CAN FD), Ethernet 10/100 Mbit, 18 PWM pins, 16 analog pins, 7 UART lines, 3 I2C lines, 2 SPI lines, 2 3.3V output pins, and 2 5V output pins. It will use the Teensy 4.1 bootloader, have 8 Mbyte flash memory, a vertical ethernet connector, and a vertical USB-C 2.0 port.

Currently, I am in the early stages of the layout, and it is proving to be a significant step up in difficulty from previous boards I have made. This board is 6 layers, and requires much more thought in regards to signal integrity and routing due the large BGA processor, as well as the number of 0402 components packed together so closely. Despite this, I am excited to increase my engineering experience and can't wait to get the board in my hands and start testing.

CU Hyperloop Website

The team at the Not-A-Boring Competition 2024

TBM Cutter Head

2023-24 Hexapod Board in Custom Enclosure

2025 Hexapod Board

Controls 6 10kN linear actuators which provide digging force for the TBM.

Features:

6 30A motor drivers
1400uF capacitors for filtering
Ethernet
Ambient temperature sensing
6 hall effect sensor inputs
12V-5V step down for lower power components
Teensy 4.1 microcontroller
Current sensing for each actuator for PID control
ADC multiplexor with i2c communication
Designed using Fusion360 Electronics

Completed Hexapod Board RevA. There are large wires bridging over a failed reverse polarity circuit due to an oversight on how the chip turns on.

Custom Arduino Board

This is an image from inside our custom power distribution box from the 2025 competition year. This box distributed up to 36.1kW of power from a 100kW 480VAC generator. It supplied a 15kVA 480delta to 208Y/120 transformer which powered all our in machine electronics. It also supplied a rectifier fpr converting 480VAC into 100VDC for our 25kW PMSM excavation motor, controlled by an inverter. There is GFCI protection on major branches, breakers, contactors, and safety relays for handling faults, as well as voltage and current monitoring for making sure our machine is under nominal operation.

More coming soon (Custom STM32 dev board; Other boards I made for CU Hyperloop; project R.A.V.E.N 🤫)

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