The Pico Doom example loaded with the ILI9341 dangling on three
critical pins:
- VCC — unconnected (no 3V3 from the Pico)
- GND — unconnected (no return path)
- MISO — unconnected
On real hardware the TFT wouldn't power on at all without VCC/GND.
Inside the velxio simulator the missing power isn't strictly fatal
(the simulator drives pixels off the SPI bus, not the rail), but it
makes the schematic incorrect and misleading for users who copy it
to a breadboard. MISO is electrically idle for write-only drivers,
but Adafruit_ILI9341 with the 3-arg constructor binds to hardware
SPI0, so MISO physically maps to GP16 — leaving it floating leaves
the SPI bus topology incomplete.
Wires added:
Pico 3V3 → tft1.VCC (red)
Pico GND.5 → tft1.GND (black) — closest GND pad to GP17/18/19
Pico GP16 → tft1.MISO (amber) — hardware SPI0 MISO
Updated the data-integrity test (examples-pico-doom.test.ts) to
include the three new pairs in the SPI/control/power expectation
map. 10/10 tests pass.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
A new entry in the games category for the Raspberry Pi Pico. Renders
a first-person 3D corridor à la Wolfenstein / early Doom using a
column-wise DDA raycaster — 160 rays per frame drawn straight to a
320×240 ILI9341 TFT via drawFastVLine, no framebuffer. 16×16 tile map
with 5 wall palettes (slate, blood, brown, toxic green, bronze door),
darkened on NS faces so corners read in 3D. Forward / back move,
two more buttons turn the player. 40-px HUD bar.
Why a demo, not the canonical id Software Doom: Graham Sanderson's
rp2040-doom port shoehorns DOOM1.WAD into 2 MB of flash with custom
compression and pushes video out over PIO-driven DVI / VGA — none of
that survives the rp2040js emulator (no PIO accuracy, no flash
mapping for huge assets). A raycaster reproduces the *visual* of
early Doom using only ~67 KB of flash and 9 KB of RAM, which the
emulator runs perfectly.
Pre-flight: arduino-cli compile against rp2040:rp2040:rpipico
already verified inside the Velxio backend container — 3 % flash,
3 % RAM. The Adafruit_GFX + Adafruit_ILI9341 libs the example
declares are already in the gallery's auto-install list.
Bundled:
test/pico_doom_demo/arduino_sketch.ino — source of truth sketch
test/pico_doom_demo/README.md — what + why + pin map
test/pico_doom_demo/compile_check.sh — operator script that
runs arduino-cli against the same FQBN the prod backend uses
frontend/src/data/examples.ts — gallery entry (boardType
raspberry-pi-pico, category games, difficulty advanced, 5
components, 14 wires)
frontend/src/__tests__/examples-pico-doom.test.ts — 10 vitest
assertions: example is registered exactly once, target board /
category / difficulty match, libraries declared, all four
pushbuttons present, every wire endpoint references a real
component id, SPI pin mapping matches the sketch's #define
block, every button has a GND wire, the renderFrame loop is
still present in the embedded code.
David Montero Crespo