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 does.
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 breakpoints.
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
Setup
1. Set the Cargo runner
The recommend way to use probe-run is to set as the Cargo runner of your application.
Add these two lines to your Cargo configuration file (.cargo/config.toml) and set the particular --chip value for your target. In this case it is nRF52840_xxAA for the nRF52840:
[target.'cfg(all(target_arch = "arm", target_os = "none"))']
runner = "probe-run --chip nRF52840_xxAA"
# ^^^^^^^^^^^^^
To list all supported chips run probe-run --list-chips.
1.1 Env variable
To support multiple devices, or permit overriding default behavior, you may prefer to:
- set the
${PROBE_RUN_CHIP}environment variable, and - set
runner(orCARGO_TARGET_${TARGET_ARCH}_RUNNER) toprobe-run:
[target.'cfg(all(target_arch = "arm", target_os = "none"))']
runner = "probe-run"
1.2 Multiple probes
If you have several probes connected, you can specify which one to use by adding the --probe option to the runner or setting the ${PROBE_RUN_PROBE} environment variable with a value containing either ${VID}:${PID} or ${VID}:${PID}:${SERIAL}:
// --probe
$ probe-run --probe '0483:3748' --chip ${PROBE_RUN_CHIP}
// PROBE_RUN_PROBE
$ PROBE_RUN_PROBE='1366:0101:123456' cargo run
To list all connected probes, run probe-run --list-probes.
2. Enable debug info
Next check that debug info is enabled for all profiles. If you are using the cortex-m-quickstart template then this is already the case. If not check or add these lines to Cargo.toml.
[dependencies]
...
panic-probe = { version = "0.2", features = ["print-rtt"] }
# Cargo.toml
[profile.dev]
debug = 1 # default is `true`; not needed if not already overridden
[profile.release]
debug = 1 # default is `false`; using `true` is also OK as symbols reside on the host, not the target
3. Look out for old dependencies
The cortex-m dependency must be version 0.6.3 or newer. Older versions are not supported. Check your Cargo.lock for old versions. Run cargo update to update the cortex-m dependency if an older one appears in Cargo.lock.
4. Run
You are all set. You can now run your firmware using cargo run. For example,
use cortex_m::asm;
use cortex_m_rt::entry;
use panic_probe as _;
use rtt_target::rprintln;
#[entry]
fn main() -> ! {
rtt_init_print!(); // You may prefer to initialize another way
rprintln!("Hello, world!");
loop { asm::bkpt() }
}
would output
$ cargo run --bin hello
Finished dev [unoptimized + debuginfo] target(s) in 0.07s
Running `probe-run --chip nRF52840_xxAA target/thumbv7em-none-eabihf/debug/hello`
(HOST) INFO flashing program (30.22 KiB)
(HOST) INFO success!
────────────────────────────────────────────────────────────────────────────────
INFO:hello -- Hello, world!
────────────────────────────────────────────────────────────────────────────────
(HOST) INFO exiting because the device halted.
To see the backtrace at the exit point repeat this run with
`probe-run --chip nRF52840_xxAA target/thumbv7em-none-eabihf/debug/hello --force-backtrace`
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()
}
Finished dev [optimized + debuginfo] target(s) in 0.04s
Running `probe-run --chip nRF52840_xxAA target/thumbv7em-none-eabihf/debug/hard-fault`
(HOST) INFO flashing program (30.08 KiB)
(HOST) INFO success!
────────────────────────────────────────────────────────────────────────────────
stack backtrace:
0: HardFaultTrampoline
If we look at the return code emitted by this cargo run, we'll see that it is non-0:
$ echo $?
134
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 data cable:
- 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.
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.
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