Moving to micro-ROS with Teensy 4.1

Why Switch?

After working with the Arduino Mega for the rover’s low-level control, I wanted something that could handle more direct ROS integration. The Teensy 4.1 brings more processing power and plenty of headroom for future features. With micro-ROS, the microcontroller is no longer just a “dumb” serial device—it becomes a true ROS 2 node, making everything from feedback to firmware updates much more seamless.

Getting micro-ROS to Compile on Teensy

The upgrade wasn’t plug-and-play. Right out of the gate, the micro-ROS Arduino library wouldn’t build for Teensy 4.1. Most of the issues were related to how Arduino IDE and Teensyduino handle precompiled libraries.

The fix:

• Install the Teensyduino library version 1.57.3 if you’re using Arduino IDE 2.0.4 or later.
• Follow the workaround from this PJRC forum post which explains how to patch Teensy’s build scripts to support precompiled static libraries (required for micro-ROS).

Once these changes were in, the micro-ROS basic publisher example compiled and uploaded without error.

Connection Stability

Compiling is only half the battle—getting a reliable connection to the micro-ROS agent can still be a struggle. The Teensy node sometimes drops out or fails to reconnect, especially after resets. The example code from the micro-ROS repo uses a simple state machine to attempt reconnection, which is a great starting point:

switch (state) {
  case WAITING_AGENT:
    // Try to ping agent
    break;
  case AGENT_AVAILABLE:
    // Attempt entity creation
    break;
  case AGENT_CONNECTED:
    // Run executor
    break;
  case AGENT_DISCONNECTED:
    // Clean up and retry
    break;
}

This approach helps but isn’t flawless; occasional dropouts still happen and need manual intervention. It’s something to keep iterating on.

Next Steps

Extend the micro-ROS node to publish actual rover sensor data (encoders, battery voltage) and subscribe to velocity commands from ROS 2.

Work on making the connection more robust—potentially by tweaking timeouts, retry intervals, or agent serial settings.

Migrate the rest of the hardware driver logic over to micro-ROS to take full advantage of native ROS integration.

Final Thoughts

The move to Teensy 4.1 and micro-ROS is a big leap forward for the rugged rover project. The process can be bumpy, especially with micro-ROS’s current build system, but it’s absolutely possible with the right combination of tools and workarounds.

If anyone else is attempting micro-ROS on Teensy and hits a roadblock, I highly recommend checking the PJRC forums for up-to-date solutions.