This repository contains test firmware and build configuration for building and running micro-ROS on the Raspberry Pi RP2350 (ARM Cortex-M33 cores) microcontroller, with multi-threading and Symmetric Multi Processing (SMP) support.
Take a look at the rp2040-backport branch if you want to benefit from some of the workflow improvements (as well as the move to v2 of the Pico SDK) made during the RP2350 transition, with your RP2040 projects.
I used code and configuration files I had prepared for running micro-ROS on the RP2040 as a base for the RP2350. I did however have to make a number of changes, not only because of the new chip, but also because I had to finally migrate away from version 1.5.1 of the Pico SDK to version 2.x.x.
Some header files were moved around, and some were separated and re-structured. This is relevant for the micro-ROS build configuration, as because we're building with FreeRTOS support (and the FreeRTOS port #includes several Pico SDK headers), we have to manually include specific directories from the Pico SDK in the CMake configuration.
Other than that, most other changes to the micro-ROS build configuration were ones made as a result of the different CPU architecture used by the RP2350's ARM cores (ARM Cortex-M0+ for RP2040 vs. ARM Cortex-M33 for RP2350), we're not using the Hazard 3 Risc-V cores here.
When testing micro-ROS with FreeRTOS on the RP2040 months ago, I was unable to get multi-core operation to work. Multi-threading on core 0 worked fine, however, if I called any RCL functions from core 1, the processor would deadlock.
I did not spend much effort to try to fix this issue, though I suspect it was a bug in some locking code somewhere, so I created an abstraction that allowed me to "publish" messages from both cores, whilst only calling rcl_publish() from core 0. This was not ideal (and resulted in some message lifetime issues, as message publication was asynchronous), but it worked.
I am happy to report, however, that everything functions perfectly on the new RP2350, and that there is no need for such an abstraction. The example provided in this repository publishes from, and runs an executor on both cores.
The example program provided in this repository is meant to be a starting point, and a demonstration of multi-threaded and multi-core operations using micro-ROS and FreeRTOS on the RP2350. It doesn't rely on any external libraries (other than the FreeRTOS Kernel, micro-ROS, and the standard Pico C SDK libraries, of course).
The example program publishes a randomly generated, 2-digit integer from both cores to two topics (core0_pub and core1_pub, with message type std_msgs/msg/Int32). It also subscribes to two topics, one for each core (core0_sub and core1_sub, with message type std_msgs/msg/Int32). The data of any messages published on core0_sub and core1_sub are displayed using the debug log output.
Subscription callbacks (and service server callbacks) are called from the executor spin functions, so which core the callbacks are called from depends on which core the executor is being spun from. For this reason, we have two executor instances in this program. One is spun by the core 0 task, and the other by the core 1 task. Each executor is subscribed to one topic (core0_sub and core1_sub for core 0 and core 1, respectively).
By default, micro-ROS data is sent using serial over the Pico's USB port, and debug log output is sent over UART 0 (pins GP0 and GP1). This behavior can be changed if needed by setting USE_UART_TRANSPORT to 1.
There will be two scripts in the working directory (well, they're located in a folder called uros_agent) of the devcontainer. You must first run the agent creation script (bash uros_agent_create.sh), and then to run the agent you can use the run script (bash uros_agent_run.sh ttyACM0, replace ttyACM0 with whichever port your Pico is connected to).
You can contact me via e-mail.
E-mail: samyarsadat@gigawhat.net
If you think that you have found a bug or issue please report it here.
| Role | Name |
|---|---|
| Lead Developer | Samyar Sadat Akhavi |
Copyright © 2025 Samyar Sadat Akhavi.