A set of tools to plot values from the target to graph in rerun with minimal performance impact. This project is based on code from probe-rs, defmt and cortex_m's singleton macro. It also uses rerun for visualization.

• probe-plotter - The target side library
• probe-plotter-tools - The host side application

#![no_std]
#![no_main]

use cortex_m_rt::entry;

use defmt_rtt as _;
use panic_halt as _;
use probe_plotter::{make_metric, make_setting};

#[entry]
fn main() -> ! {
    defmt::println!("Running...");
    let mut sawtooth = make_metric!(SAWTOOTH: i32 = 42, "(SAWTOOTH / 10) % 100").unwrap();
    defmt::println!("sawtooth initialized to: {}", sawtooth.get());
    let mut sine = make_metric!(SINE: i32 = 42, "100 * sin(2 * pi * SINE / 4000)").unwrap();

    let mut setting_roundtrip =
        make_metric!(SETTING_ROUNDTRIP: i8 = 0, "SETTING_ROUNDTRIP").unwrap();

    // Allow values -1..=7, step by 2, so {-1, 1, 3, 5, 7}
    let mut setting = make_setting!(SETTING: i8 = 5, -1..=7, 2).unwrap();

    loop {
        for i in 0..i32::MAX {
            sawtooth.set(i);
            sine.set(i);

            setting_roundtrip.set(setting.get());
        }
    }
}

The formulas seen in the make_metric macro invocation are computed by the host and will thus have zero impact on the targets performance. The set method on the metrics object is simply a volatile store which is quite cheap. The host will then read that value using the debug probe at regular intervals and update the graph on any changes.

probe-plotter uses the Rerun viewer for visualizing the graphs. Please make sure to have that installed. Also make sure to have libudev installed.

cd probe-plotter-host
cargo run --bin custom-viewer /path/to/elf chip_name

So for example plotting the example in examples/simple on a Nucleo-G474RE

cd examples/simple
cargo run # Let it flash and then cancel (Ctrl+C) to let the target continue running in the background while giving up access to the probe

cd ../probe-plotter-tools
cargo run --bin custom-viewer ../examples/simple/target/thumbv7em-none-eabihf/debug/simple stm32g474retx
# Rerun will open with a graph showing all created metrics objects and a panel with settings at the right hand side

This would never have been possible without the help of the following projects. Thank you!

Lots of the macro code is based on code from defmt and the singleton macro from cortex-m. The code for finding and decoding elf symbols is based on defmt and probe-rs. The custom viewer is based on an example from rerun.

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.

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 dual licensed as above, without any additional terms or conditions.