pm-kit: defmt+probe-rs diagnostics + flip-link toolchain

Adopt proper embedded tooling for the blank-screen debug (user has a Pi Debug Probe):
- flip-link linker (baked into pm-rust:2): stack overflow faults cleanly instead of
  silently corrupting .bss/.data (the SPI buffer -> black screen class of bug).
- defmt + defmt-rtt + panic-probe: firmware logs boot/heap-free/display/parse/loop
  heartbeat over RTT; panics print message+location. .cargo runner = probe-rs run.
- Restore the full live metronome (from 08b0940) as the instrumented target.
- deploy + serve pm-kit.elf (probe-rs decodes defmt strings from the ELF).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
This commit is contained in:
Me Here 2026-06-01 08:30:35 -05:00
parent 7faca6d0d7
commit 8f4264f4d2
8 changed files with 175 additions and 15 deletions

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@ -53,6 +53,12 @@ if [[ -f "$SRC_DIR/rust/pm-kit/pm-kit.uf2" ]]; then
cp "$SRC_DIR/rust/pm-kit/pm-kit.uf2" "$DEST_DIR/pm-kit.uf2"
echo " pm-kit.uf2 ($(stat -c '%s' "$DEST_DIR/pm-kit.uf2") bytes) # Rust RP2350 firmware (alpha live metronome)"
fi
# ELF with defmt info — `probe-rs run --chip RP235x pm-kit.elf` flashes over the Debug Probe and
# streams logs/panics. Needed locally (not the uf2) because defmt decodes log strings from the ELF.
if [[ -f "$SRC_DIR/rust/pm-kit/pm-kit.elf" ]]; then
cp "$SRC_DIR/rust/pm-kit/pm-kit.elf" "$DEST_DIR/pm-kit.elf"
echo " pm-kit.elf ($(stat -c '%s' "$DEST_DIR/pm-kit.elf") bytes) # probe-rs flash + defmt RTT logging"
fi
cp "$DIST_DIR/pm_k1_circuitpy.zip" "$DEST_DIR/pm_k1_circuitpy.zip"; echo " pm_k1_circuitpy.zip ($(stat -c '%s' "$DEST_DIR/pm_k1_circuitpy.zip") bytes)" # PM_K-1 CircuitPython bundle
cp "$DIST_DIR/pico-cp-app.py" "$DEST_DIR/pico-cp-app.py"; echo " pico-cp-app.py ($(stat -c '%s' "$DEST_DIR/pico-cp-app.py") bytes)" # served for version reading + reference
cp "$DIST_DIR/pico-cp-app.mpy" "$DEST_DIR/pico-cp-app.mpy"; echo " pico-cp-app.mpy ($(stat -c '%s' "$DEST_DIR/pico-cp-app.mpy") bytes)" # precompiled firmware the editor pushes (base64)

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@ -3,6 +3,8 @@
FROM docker.io/library/rust:1-slim
# Cortex-M33 target for the eventual RP2350 firmware. Harmless for the host tests.
RUN rustup target add thumbv8m.main-none-eabihf
RUN rustup target add thumbv8m.main-none-eabihf \
&& rustup component add llvm-tools-preview \
&& cargo install flip-link # stack-overflow-safe linker (overflow faults instead of corrupting statics)
WORKDIR /work/rust

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@ -2,7 +2,16 @@
target = "thumbv8m.main-none-eabihf"
[target.thumbv8m.main-none-eabihf]
# flip-link: places the stack BELOW the statics so a stack overflow hits a guard region
# and faults cleanly instead of silently corrupting .bss/.data (e.g. the SPI buffer → black screen).
linker = "flip-link"
# `cargo run` flashes over the Raspberry Pi Debug Probe and streams defmt logs/panics via RTT.
runner = "probe-rs run --chip RP235x"
rustflags = [
"-C", "link-arg=--nmagic",
"-C", "link-arg=-Tlink.x",
"-C", "link-arg=-Tdefmt.x", # defmt's linker section for log-string interning
]
[env]
DEFMT_LOG = "debug"

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@ -2,3 +2,4 @@ target/
Cargo.lock
*.uf2
*.bin
*.elf

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@ -5,9 +5,11 @@ edition = "2021"
description = "PM_K-1 firmware (RP2350 / Pico 2). Stage 3 bring-up: boot blink → display → drivers + pm-core."
[dependencies]
rp235x-hal = { version = "0.3", features = ["binary-info", "critical-section-impl", "rt"] }
rp235x-hal = { version = "0.3", features = ["binary-info", "critical-section-impl", "rt", "defmt"] }
cortex-m-rt = "0.7"
panic-halt = "1"
defmt = "0.3"
defmt-rtt = "0.4"
panic-probe = { version = "0.3", features = ["print-defmt"] }
embedded-hal = "1"
embedded-hal-0-2 = { package = "embedded-hal", version = "0.2.7" } # ADC OneShot trait (rp235x-hal ADC)
embedded-hal-bus = "0.2"

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@ -10,7 +10,7 @@ set -euo pipefail
DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)" # rust/pm-kit
REPO="$(cd "$DIR/../.." && pwd)" # repo root
RUNTIME="${RUNTIME:-podman}"
IMG="pm-rust:1"
IMG="pm-rust:2"
"$RUNTIME" run --rm -v "$REPO":/work:Z -w /work/rust/pm-kit "$IMG" bash -c '
set -e

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@ -23,7 +23,9 @@ use mipidsi::interface::{Interface, SpiInterface};
use mipidsi::models::ST7796;
use mipidsi::options::{ColorInversion, ColorOrder, Orientation};
use mipidsi::Builder;
use panic_halt as _;
use defmt::info;
use defmt_rtt as _; // global defmt logger over RTT (read by `probe-rs run`)
use panic_probe as _; // panic handler that prints the message + location over defmt, then halts
use rp235x_hal as hal;
use hal::fugit::RateExtU32;
use hal::Clock;
@ -57,12 +59,13 @@ impl OutputPin for NoCs {
#[hal::entry]
fn main() -> ! {
// heap for track parsing (track-format uses alloc). RP2350 has 520 KB SRAM.
const HEAP_SIZE: usize = 96 * 1024;
{
use core::mem::MaybeUninit;
const HEAP_SIZE: usize = 16 * 1024;
static mut HEAP_MEM: [MaybeUninit<u8>; HEAP_SIZE] = [MaybeUninit::uninit(); HEAP_SIZE];
unsafe { HEAP.init(core::ptr::addr_of_mut!(HEAP_MEM) as usize, HEAP_SIZE) }
}
info!("== pm-kit boot == heap {}KB, {} free", HEAP_SIZE / 1024, HEAP.free());
let mut pac = hal::pac::Peripherals::take().unwrap();
let mut watchdog = hal::Watchdog::new(pac.WATCHDOG);
@ -149,24 +152,161 @@ fn main() -> ! {
.orientation(Orientation::new().flip_horizontal())
.init(&mut timer)
.unwrap();
info!("display init ok, {} free", HEAP.free());
// ---- MINIMAL ISOLATION ----
// Heap is initialised above. Exercise the allocator once (parse), then just draw the
// confirmed-working pattern in a loop. No inputs/audio/clock. If the screen shows blue +
// corners → heap + parse + display are all fine and the bug is in the metronome loop logic.
// If still black → the heap/parse path breaks the display.
// (parse removed for this test — heap init only)
// ---- inputs + speaker ----
let mut btn_a = pins.gpio15.into_pull_up_input(); // A = play/stop
let mut btn_b = pins.gpio14.into_pull_up_input(); // B = grid/notation view
let mut adc = hal::adc::Adc::new(pac.ADC, &mut pac.RESETS);
let mut joy_x = hal::adc::AdcPin::new(pins.gpio26).unwrap();
let mut joy_y = hal::adc::AdcPin::new(pins.gpio27).unwrap();
let pwm_slices = hal::pwm::Slices::new(pac.PWM, &mut pac.RESETS);
let mut spk = pwm_slices.pwm6; // GP13 = PWM slice 6, channel B
spk.set_div_int(125);
spk.set_top(600); // ~2 kHz click
spk.enable();
spk.channel_b.output_to(pins.gpio13);
// ---- built-in grooves ----
const GROOVES: [&str; 4] = [
"t120;kick:4=X.x.;snare:4=.X.X;hatClosed:4/2=xxxxxxxx",
"t92;kick:4/3=X....x...x..;snare:4/3=..gg.gX.gg.g;hatClosed:4/3=X.xX.xX.xX.x",
"t140;kick:4=X..x;snare:4=.X.X;hatClosed:4/4=xxxxxxxxxxxxxxxx",
"t100;kick:4=Xxxx;claves:5=Xxxxx~",
];
const NAMES: [&str; 4] = ["Four on the floor", "Half-time shuffle", "Driving 16ths", "5 over 4"];
let mut idx = 0usize;
let mut track = track_format::parse(GROOVES[idx]);
info!("parsed groove 0: bpm={} lanes={}, {} free", track.bpm, track.lanes.len(), HEAP.free());
let mut tempo: i64 = track.bpm;
let mut playing = true;
let mut notation = false;
let mut bar_start = timer.get_counter().ticks();
let mut last_step = usize::MAX;
let mut click_off_us: u64 = 0;
let (mut pa, mut pb) = (false, false);
let mut joy_zone = 0i8;
let mut full_redraw = true;
let mut last_draw_us = 0u64;
let mut hb = false;
let mut hb_us = 0u64;
let mut last_draw_ok = false;
led.set_low().unwrap();
info!("entering main loop");
loop {
pm_ui::draw_ui(&mut display).ok();
let now = timer.get_counter().ticks();
// ---- inputs ----
let a = btn_a.is_low().unwrap_or(false);
let b = btn_b.is_low().unwrap_or(false);
if a && !pa {
playing = !playing;
if playing {
bar_start = now;
last_step = usize::MAX;
}
full_redraw = true;
}
if b && !pb {
notation = !notation;
full_redraw = true;
}
pa = a;
pb = b;
let jx = adc.read(&mut joy_x).unwrap_or(2048);
let jy = adc.read(&mut joy_y).unwrap_or(2048);
// rotate the joystick reading 90° CCW for control
let rx = jy as i32;
let ry = 4095 - jx as i32;
let zone: i8 = if ry > 3200 { 1 } else if ry < 900 { 2 } else if rx > 3200 { 3 } else if rx < 900 { 4 } else { 0 };
if zone != 0 && joy_zone == 0 {
match zone {
1 => tempo = (tempo + 4).min(300), // up → tempo+
2 => tempo = (tempo - 4).max(30), // down → tempo-
3 => {
idx = (idx + 1) % GROOVES.len(); // right → next groove
track = track_format::parse(GROOVES[idx]);
tempo = track.bpm;
bar_start = now;
last_step = usize::MAX;
}
4 => {
idx = (idx + GROOVES.len() - 1) % GROOVES.len(); // left → prev
track = track_format::parse(GROOVES[idx]);
tempo = track.bpm;
bar_start = now;
last_step = usize::MAX;
}
_ => {}
}
full_redraw = true;
}
joy_zone = zone;
// ---- clock ----
let master = &track.lanes[0];
let msteps = master.levels.len().max(1) as u64;
let beats = master.groups.iter().map(|&g| g as u64).sum::<u64>().max(1);
let bar_us = 60_000_000u64 * beats / tempo.max(1) as u64;
let step_us = (bar_us / msteps).max(1);
let elapsed = now.wrapping_sub(bar_start) % bar_us;
let cur_step = (elapsed / step_us) as usize;
let phase = elapsed as f32 / bar_us as f32;
// ---- audio: click on a new step that has a hit ----
if playing && cur_step != last_step {
let lvl = master.levels[cur_step.min(msteps as usize - 1)];
if lvl > 0 {
let _ = spk.channel_b.set_duty_cycle(if lvl == 2 { 380 } else { 240 });
click_off_us = now + if lvl == 2 { 28_000 } else { 14_000 };
}
last_step = cur_step;
}
if now >= click_off_us {
let _ = spk.channel_b.set_duty_cycle(0);
}
// ---- draw: on change, and periodically (so a draw lost right after init reappears, and
// the playhead advances). ~7 fps; partial/playhead-only redraw is the next optimization. ----
if full_redraw || now.wrapping_sub(last_draw_us) > 140_000 {
let lanes: Vec<pm_ui::LaneView> = track
.lanes
.iter()
.map(|l| pm_ui::LaneView {
name: &l.sound,
levels: &l.levels,
beats: l.groups.iter().map(|&g| g as u32).sum::<u32>().min(255) as u8,
poly: l.poly,
muted: l.mute,
})
.collect();
let screen = pm_ui::Screen { name: NAMES[idx], bpm: tempo, playing, phase, lanes: &lanes };
last_draw_ok = if notation {
pm_ui::draw_notation(&mut display, &screen).is_ok()
} else {
pm_ui::draw_metronome(&mut display, &screen).is_ok()
};
full_redraw = false;
last_draw_us = now;
}
// heartbeat LED + log (~2 Hz) — confirms the loop is alive and the last draw returned Ok
if now.wrapping_sub(hb_us) > 500_000 {
hb = !hb;
let _ = if hb { led.set_high() } else { led.set_low() };
info!("alive: idx={} step={} playing={} draw_ok={} free={}", idx, cur_step, playing, last_draw_ok, HEAP.free());
hb_us = now;
}
timer.delay_ms(50);
timer.delay_ms(8);
}
}
/// picotool metadata (visible via `picotool info`).
#[link_section = ".bi_entries"]
#[used]
pub static PICOTOOL_ENTRIES: [hal::binary_info::EntryAddr; 1] =
[hal::binary_info::rp_program_name!(c"pm-kit display")];

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@ -8,7 +8,7 @@
# Override the runtime with RUNTIME=docker ./run.sh ...
set -euo pipefail
IMG="pm-rust:1"
IMG="pm-rust:2"
RUST_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)" # rust/
REPO_DIR="$(cd "$RUST_DIR/.." && pwd)" # repo root
RUNTIME="${RUNTIME:-podman}"