probe-run

⚠️ As of 11.10.2023 probe-run is in maintainance mode. We recommend everyone to switch to probe-rs. Read following article on the why and on how to migrate: https://ferrous-systems.com/blog/probe-run-deprecation/

probe-run

Runs embedded programs just like native ones

probe-run is a custom Cargo runner that transparently runs Rust firmware on an embedded device.

probe-run is powered by probe-rs and thus supports all the devices and probes supported by probe-rs.

Features

• Acts as a Cargo runner, integrating into cargo run.
• Displays program output streamed from the device via RTT.
• Exits the firmware and prints a stack backtrace on hardware breakpoints (e.g. bkpt), Rust panics and unrecoverable hardware exceptions (e.g. HardFault).

Installation

To install probe-run, use cargo install probe-run.

On Linux, you might have to install libudev and libusb from your package manager before installing probe-run.

# ubuntu
$ sudo apt install -y libusb-1.0-0-dev libudev-dev

# fedora
$ sudo dnf install -y libusbx-devel systemd-devel

Using the latest probe-rs

probe-run inherits device support from the probe-rs library. If your target chip does not appear in the output of probe-run --list-chips it could be that:

1. The latest git version probe-rs supports your chip but the latest version on crates.io does not. You could try building probe-run against the latest probe-rs version; see instructions below.
2. probe-rs does not yet support the device. You'll need to request support in the probe-rs issue tracker.

To build probe-run against the latest git version probe-rs and install it follow these steps:

$ # clone the latest version of probe-run; line below uses version v0.3.3
$ git clone --depth 1 --branch v0.3.3 https://github.com/knurling-rs/probe-run

$ cd probe-run

$ # modify Cargo.toml to use the git version of probe-rs
$ # append these lines to Cargo.toml; command below is UNIX-y
$ cat >> Cargo.toml  ! {
    rtt_init_print!(); // You may prefer to initialize another way
    rprintln!("Hello, world!");
    loop { asm::bkpt() }
}

would output

…

Stack backtraces

When the device raises a hard fault exception, indicating e.g. a panic or a stack overflow, probe-run will print a backtrace and exit with a non-zero exit code.

This backtrace follows the format of the std backtraces you get from std::panic! but includes `` lines to indicate where an exception/interrupt occurred.

#![no_main]
#![no_std]

use cortex_m::asm;
#[entry]
fn main() -> ! {
    // trigger a hard fault exception with the UDF instruction.
    asm::udf()
}

…

If we look at the return code emitted by this cargo run, we'll see that it is non-0:

$ echo $?
134

⚠️ NOTE when you run your application with probe-run, the HardFault handler (default or user-defined) will NOT be executed.

Backtrace options

--backtrace

The --backtrace flag is optional and can get passed the following values:

• --backtrace=always - forced backtrace (if you'd like to see a backtrace at the end of successful program run)
• --backtrace=never - suppresed backtrace
• --backtrace=auto - default, shows a backtrace if the program panics or the stack overflows

Run it like this (example for a forced backtrace):

$ cargo run --bin hello --backtrace=always

--backtrace-limit

The --backtrace-limit flag is optional and defaults to 50. It is possible to set any number.

--backtrace-limit=0 is accepted and means "no limit".

To show a shortened backtrace showing 5 frames, run:

$ cargo run --bin panic --backtrace-limit=5

Note: if --backtrace=never is set, setting --backtrace-limit has no effect.

Troubleshooting

"Error: no probe was found."

First, check your hardware:

• make sure that your development board has an on-board hardware debugger. If it doesn't, you'll need a separate hardware debugger that works with the JTAG or SWD interface. Some boards have a USB micro-B or Type-C connector but only come with bootloader firmware that lets you load new program over USB Mass Storage, instead of having a dedicated on-board JTAG or SWD to USB chip; probe-run cannot be used with these boards.
• make sure that it is connected to the right port on your development board
• make sure that you are using a data cable– some cables are built for charging only! When in doubt, try using a different cable.
• make sure you have the right drivers for the debugger installed (st-link or j-link)

If this doesn't resolve the issue, try the following:

[Linux only] udev rules haven't been set

Check if your device shows up in lsusb:

$ lsusb
Bus 001 Device 008: ID 1366:1015 SEGGER J-Link

If your device shows up like in the example, skip to the next troubleshooting section

If it doesn't show up, you need to give your system permission to access the device as a non-root user so that probe-run can find your device.

In order to grant these permissions, you'll need to add a new set of udev rules.

To learn how to do this for the nRF52840 Development Kit, check out the installation instructions in our embedded training materials.

afterwards, your device should show up in probe-run --list-probes similar to this:

$ probe-run --list-probes
The following devices were found:
[0]: J-Link (J-Link) (VID: 1366, PID: 1015, Serial: , JLink)

No external or on-board debugger present

To use probe-run you need a "probe" (also known as "debugger") that sits between your PC and the microcontroller.

Most development boards, especially the bigger ones, have a probe "on-board": If the product description of your board mentions something like a J-Link or ST-Link on-board debugger you're good to go. With these boards, all you need to do is connect your PC to the dev board using a USB cable you are all set to use probe-run!

If this is not the case for your board, check in the datasheet if it exposes exposes SWD or JTAG pins. If they are exposed, you can connect a "stand alone" probe device to the microcontroller and then connect the probe to your PC via USB. Some examples of stand alone probes are: the ST-Link and the J-Link.

Note that this may involve some soldering if your board does not come with a pre-attached header to plug your debugger into.

Error: RTT up channel 0 not found

This may instead present as Error: RTT control block not found in target memory.

Your code, or a library you're using (e.g. RTIC) might be putting your CPU to sleep when idle. You can verify that this is the problem by busy looping instead of sleeping. When using RTIC, this can be achieved by adding an idle handler to your app:

#[idle]
fn idle(_ctx: idle::Context) -> ! {
     loop {}
}

Assuming you'd like to still sleep in order to save power, you need to configure your microcontroller so that RTT can still be handled even when the CPU is sleeping. How to do this varies between microcontrollers.

On an STM32G0 running RTIC it can be done by amending your init function to set the dmaen bit on RCC.ahbenr. e.g.:

#[init]
fn init(ctx: init::Context) -> init::LateResources {
     ctx.device.RCC.ahbenr.write(|w| w.dmaen().set_bit());
     ...
}

defmt version mismatch

end-user

Follow the instructions in the error message to resolve the mismatch.

developer

If you are hacking around with probe-run, you can disable the version check by setting the PROBE_RUN_IGNORE_VERSION environment variable to true or 1 at runtime.

Developer Information

running your locally modified probe-run

For easier copy-paste-ability, here's an example how to try out your local probe_run modifications.

$ cd probe-run/
$ PROBE_RUN_IGNORE_VERSION=1 cargo run -- --chip nRF52840_xxAA --backtrace-limit=10 hello
  ˆˆˆˆˆˆˆˆˆˆˆˆˆˆˆˆˆˆˆˆˆˆˆˆˆˆ                                   ˆˆˆˆˆˆˆˆˆˆˆˆˆˆˆˆˆˆˆˆˆˆ ˆˆˆˆˆ
  environment variables                                        extra flags             binary to be
  (optional)                                                   (optional)              flashed & run

running snapshot tests

To check whether your change has altered probe-run in unexpected ways, please run the snapshot tests in tests before opening a PR if at all possible.

You can do so by connecting a nrf52840 Development Kit and running

$ cargo test -- --ignored

Support Us

probe-run is part of the Knurling project, Ferrous Systems' effort at improving tooling used to develop for embedded systems.

If you think that our work is useful, consider sponsoring it via GitHub Sponsors.

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)

• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be licensed as above, without any additional terms or conditions.