probe-rs is an embedded debugging and target interaction toolkit. It enables its user to program and debug microcontrollers via a debug probe.

probe-rs helps you with

• Flashing firmware to ARM and RISC-V targets. More architectures are in the works.
• Reading and writing memory, running, halting, setting and reading breakpoints and resetting the target via SWD and JTAG.
• Running firmware on the target and getting back logs via RTT and defmt and printing a stacktrace on panic.
• Debugging the target via VS Code with running RTT logs, memory inspection and more.

This article explains embedded debugging in a bit more detail and where probe-rs fits in. You can skip it if you are familiar with embedded debugging.{.tip}

Embedded debugging

In most programming fields the software can be written on a computer system akin to the system the software is finally executed on. It hosts an OS, which has processes, network access and most likely even GUI.

For embedded systems, this is different. The software run on a target that is severely limited in its capabilities. It does not run an operating system and has very limited IO. To be able to download (aka flash) the software from a host system to the target or debug the target with a debugger, the targets debug interface has to be used. That interface is different depending on the targets architecture, but is very rudimentary and based on reading and writing certain target memory regions that control the debug system of the target.

Modern computers have interfaces - such as USB - much more advanced than the targets and cannot use the protocol natively. For this reason a debug probe is required which translates from the host interface - mostly USB but sometimes Ethernet - to the target interface - for ARM e.g. this would be SWD.

Some newer targets have DFU (device firmware upgrade) support via USB, but cannot be debugged via such. DFU is handy for just flashing targets, but due to its severe limitations is not suitable for debugging and writing said software.

probe-rs

probe-rs is a library that implements the protocols of debug probes from various manufacturers and the protocols of different chip architectures. It furthermore is able to flash many targets and download software onto them.

While probe-rs was originally targeted at the Rust community, it can freely be used for programming in C as well.