Engineering & Robotics

2025 · in progress

STM32 Odometry Computer

An embedded robotics board concept for improving FTC field position estimation with better heading data and faster odometry updates.

Overview

In FIRST Tech Challenge, accurate field position data is central to high-performance autonomous driving, and tracking wheel integration is one of the most common ways teams estimate robot motion. If mechanical slip is held equal, the two largest factors are heading drift/error and integration update rate. I set out to create an STM32-based odometry computer that could improve both.

Goals

Provide higher quality heading data using a modern IMU, rather than the outdated IMU in the FTC control system
Pre-integrate encoder inputs at a high frequency, decoupled from the main robot code loop rate

What it involved

Learning STM32 hardware board design
Writing STM32 HAL C code
Setting up the STM32 project and firmware workflow

Breadboard prototype

Before committing the design to a custom PCB, I built and tested the core sensing and integration idea with a Nucleo and breadboard.

Brought up the IMU, and encoder input path on a breadboard
Used the prototype to validate the firmware approach before board design
Moved from breadboard testing into a Rev 1 PCB

First STM32 odometry computer breadboard prototype — Nucleo testbed

STM32 odometry breadboard prototype connected to a test cube — CubeIDE setup

Rev 1 Board

The Rev 1 board turned the breadboard prototype into a compact STM32-based hardware platform for odometry and sensor integration.

STM32F4 microcontroller with USB
ISM330 IMU for modern heading data
Bidirectional ESD protection on all IO
Input power mux to prevent USB backfeed

STM32 Odometry Computer Rev 1 board — Rev 1 board

STM32 odometry computer peripheral setup — Peripheral setup

STM32 Odometry Computer Rev 1 schematic — Rev 1 schematic

STM32 Odometry Computer Rev 1 PCB layout — Rev 1 PCB

Rev 2 Board

Rev 2 was a full re-layout focused on making the odometry computer smaller and denser.

Full PCB re-layout
Smaller board outline
Denser component placement and routing

STM32 Odometry Computer Rev 2 3D board view — Rev 2 3D view

STM32 Odometry Computer Rev 2 PCB layout — Rev 2 PCB

Panel of STM32 Odometry Computer Rev 2 boards — Rev 2 panel

STM32 Odometry Computer Rev 2 installed with Barker Greybacks hardware — Rev 2 board visible on FTC robot in YouTube interview

Software

The software work focused on turning the board into a usable odometry computer rather than just a sensor breakout.

Built STM32 HAL firmware for sensor bring-up and encoder processing
Implemented offset calibration support for practical robot setup

STM32 Odometry Computer offset calibration interface — Offset calibration