G6 Panel Firmware

Firmware for the Generation-6 modular LED-display panels (20×20, RP2354 / RP2350 core). In development.

A panel runs as an SPI peripheral: the arena controller streams display frames over SPI (MODE3), and the panel renders them on its 20×20 LED matrix.

• Core 0 ingests SPI: a DMA-paced RX captures each frame, then the Messenger validity gate checks parity / length / protocol / opcode and either dispatches the frame or raises a PEnn error glyph.
• Core 1 drives the display: binary-code-modulation (BCM) grayscale via PIO.

Wire-protocol reference: docs/development/g6_01-panel-protocol.md in the Modular-LED-Display repo.

Repository layout

Path	What it is
panel/	The panel firmware — the SPI peripheral (the production target).
panel_controller/	Bench harness: turns one panel into a fake SPI controller to drive a second panel running panel/. See panel_controller/README.md.
test_arena/	Early standalone SPI sketch used during bring-up.

Hardware revisions

Selected at build time with -DPANEL_REV (set per PlatformIO env):

Rev	PANEL_REV	SPI	Notes
v0.2.1	21	SPI0, GP32–35	PSRAM CS on GP0
v0.3.1	31	SPI1, GP40–43	PSRAM CS on GP47; columns GP0–19, rows GP20–39

Pin tables: docs/development/g6_02-led-mapping.md.

Toolchain

Build/flash tooling is provided through pixi, which installs PlatformIO into the workspace:

pixi install

All commands below run through pixi run …; you can also invoke PlatformIO directly once the environment is active.

Build

pixi run platformio run -d panel -e pico_v031      # build v0.3.1 (or pico_v021)

PlatformIO environments

Env	Build flags	Purpose
pico_v021 / pico_v031	PANEL_REV	Production firmware.
pico_v021_spidiag / pico_v031_spidiag	+ SPI_DIAG=1	Production + SPI/validity-gate serial diagnostics. Same SPI ingest — safe to deploy — but per-1000-message Serial prints run on core 0 and can cost the occasional frame.
pico_v021_bcmtest / pico_v031_bcmtest	+ STAGE2_SELFTEST=1	BCM-via-PIO visual self-test. No SPI ingest — DO NOT DEPLOY for bench testing; re-flash a production env first.

Flash & monitor

The deploy* / monitor* pixi tasks target a board by USB serial number (robust against shifting /dev/ttyACM* enumeration):

pixi run deploy31a         # build + flash production firmware to the v0.3.1 board
pixi run deploy31a-diag    # same, but the SPI_DIAG (serial diagnostics) build
pixi run monitor31a        # open the USB-serial monitor for that board

(*21a variants target the v0.2.1 board.)

These tasks are bound to two specific physical panels (the serial numbers are hardcoded in pixi.toml) and will only act on those boards. To deploy to a different panel, find its serial with ls /dev/serial/by-id/usb-Reiser_Lab_RP2354_20x20_Display_Panel_* then either add a task in pixi.toml or call the script directly:

bash panel/tools/deploy.sh <THAT_SERIAL> pico_v031

A panel stuck in BOOTSEL won't expose its serial — flash it manually with pixi run platformio run -d panel -e pico_v031 -t upload.

SPI diagnostics

With a *_spidiag build flashed, the panel prints terse histograms and the last frame's validity-gate state every 1000 messages — SPI timing (gap/proc/spi buckets), the gate p/l/pr/cmd/cc flags, leading bytes, and a parity dump on a parity miss. Useful for diagnosing dropped/short frames and parity mismatches. The instrumentation lives behind #if SPI_DIAG in panel/src/messenger.cpp.

License

MIT