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Picodroid

Advanced configuration

Most builds work without touching anything below — these files are here when you need them. Day-to-day app development needs none of this.

lv_conf.h

LVGL is vendored in vendor/lvgl/ and configured via the repo-root lv_conf.h. It overrides selected upstream defaults:

SymbolPicodroid valueWhy
LV_COLOR_DEPTH16RGB565 framebuffers — matches ST7789 + minifb.
LV_DRAW_SW_SUPPORT_RGB565A81Anti-aliased scaled / rotated images via ImageView.setScale. Without it scaled images render aliased — see LVGL release notes for 9.5.0.
LV_USE_LODEPNG / LV_USE_LIBPNG0Both PNG decoders disabled — PNG is decoded at PAPK-pack time, never on-device. See Bundled image assets.
LV_FONT_MONTSERRAT_*tuned per-boardOnly the sizes the framework actually renders are pulled in.

Bumping LVGL: vendor at vendor/lvgl, then re-vet lv_conf.h against vendor/lvgl/src/lv_conf_template.h. Anything new defaults to upstream behavior.

Embed.toml

Config for the cargo embed probe-rs subcommand, handy for interactive ARM debug sessions. Selects the chip, RTT polling rate, and breakpoint set. Defaults work for testbench RP2040 / RP2350; override only if you’re debugging a custom board with a non-standard probe wiring.

[default.general]
chip = "RP2040"


[default.rtt]
enabled = true
up_mode = "NoBlockSkip"

Note that ./scripts/flash.sh flashes via cargo run (the probe-rs runner configured in .cargo/config.toml), not cargo embed — so most users never touch this file.

.actrc

Lets you run the GitHub Actions workflows locally via the act tool, useful for catching workflow bugs before pushing to the repo:

-P ubuntu-latest=catthehacker/ubuntu:act-22.04

Install act:

Terminal window
brew install act           # macOS
gh extension install nektos/gh-act    # via gh CLI

Run the CI workflow locally:

Terminal window
act -W .github/workflows/ci_checks.yml -j build

.actrc lives at the repo root so act picks it up automatically.

scripts/test.sh (host-target test wrapper)

Bare cargo test fails because the picodroid firmware crate is bare-metal (no host test harness) and there is no default cargo target set, so cargo can’t pick a host triple on its own. scripts/test.sh runs the tests against the host triple and rebuilds the APK first so any embedded test fixtures are fresh:

Terminal window
./scripts/test.sh                # all crates
./scripts/test.sh --crate jvm    # just the JVM tests

CI uses the same wrapper, so passing locally is a strong predictor of green CI.

If you’re chasing a specific failure, scripts/test.sh -- --nocapture <test_name> forwards args through to cargo test exactly like a normal invocation.

Out-of-tree app builds

App projects under examples/ build as subprojects of the picodroid repo by default. To build an app that lives outside the repo against a picodroid checkout, point two Gradle properties at it:

Terminal window
./gradlew :myapp:assemblePapk \
    -Ppicodroid.repoRoot=/path/to/picodroid-rs \
    -Ppicodroid.sdkProjectPath=:sdk
  • picodroid.repoRoot — the picodroid source tree (holds tools/, sdk/, scripts/). Default: the build’s root project dir.
  • picodroid.sdkProjectPath — Gradle path of the :sdk project to compile against. Default :sdk.

This is path indirection only — there is no published Maven artifact or project template; the app still composes the picodroid build (e.g. via an included build).

See also