rndrSBC

Ultra-lightweight, high-performance native E-Paper operating platform designed for Single-Board Computers.

Deployment companion: rndrsbc-deploy — operator-side scaffold for the Pi (config, catalog, systemd unit).

What it is

A Chromium-free, sub-60ms, sub-15MB E-Paper dashboard OS for Single-Board Computers. It renders live dashboards (weather, calendar, news, custom widgets) directly to a low-power E-Paper panel with no web browser, no X11, no swap thrashing — designed for always-on, wall-powered frames that must run for months on a Pi Zero W. v0.3.0 adds automatic panel detection, a conventional- commit-driven semantic release pipeline, and an auto-generated CHANGELOG.

Key metrics

Why rndrSBC?

• Chromium-Free: 0MB browser bloat. No headless Chrome, no WebKit, no X11.
• Insanely Fast: Renders vector dashboards in 35ms–60ms (vs. 10–15 seconds on Chrome).
• Zero Swap & Memory Thrashing: Runs in < 15MB RAM (ideal for Pi Zero W / Pi Zero 2W / Pi 3).
• Responsive Canvas Engine: Resolution-independent vector layout with fractional split boxes and auto-scaling typography.
• 100% Clean-Room Architecture: Fully standalone with modular display drivers and widget system.

Quick Start (Development / PC / Mac)

# 1. (Optional) Vendor the runtime deps for a fully-offline copy
python3 build_vendor_deps.py

# 2. Run single-pass render test
python3 main.py --once

Output is rendered directly to live_screen.png.

Run the web dashboard (any platform)

python3 main.py 8080          # foreground
python3 main.py --daemon 8080 # background, self-detaches (no sudo)

Raspberry Pi — no install.sh required

rndrSBC is relocatable: it anchors every path (config, previews, photo library) to its own folder, and it can load its Python deps straight from a vendored wheel bundle. So deployment is simply:

# Copy the project folder onto the Pi, then:
python3 main.py 8080

Optional, per-target dependency bundle (needs internet once, on the Pi):

python3 build_vendor_deps.py            # detects this machine's arch
# or for a Raspberry Pi explicitly:
python3 build_vendor_deps.py --platform aarch64   # 64-bit OS / Pi 4+ / Pi 5
python3 build_vendor_deps.py --platform armv7l    # 32-bit OS

The resulting vendor/deps/*.whl files let the platform run fully offline with zero pip installs. Skip this and rndrSBC will fall back to your system's packages (or create a private .venv on first run).

If you want rndrSBC to start at boot (optional), use the relocatable unit:

# edit the two placeholders in rndrSBC.service, then:
sudo cp rndrSBC.service /etc/systemd/system/
sudo systemctl daemon-reload
sudo systemctl enable --now rndrSBC

A legacy install.sh is still included for compatibility, but it is no longer required.

Recent Additions (this build)

Physical Buttons (GPIO) — core/buttons.py

• Wire three buttons to GPIO 17 / 27 / 22 (to GND), enabled in the dashboard.
• NEXT cycles widgets, PREV goes back, TOGGLE-QUIET pauses/restarts refreshes.
• Falls back gracefully when RPi.GPIO is absent (simulator / laptop / CI) — buttons are auto-disabled.

CalDAV + iCal Calendar — widgets/calendar/widget.py

• Calendar widget now accepts a caldav config (URL + basic-auth user/password) in addition to public iCal feed URLs.
• Fetches via HTTPS REPORT query, parses with the native ICS parser (no extra deps); per-date event-dot markers on the month grid.

Localization (i18n) — core/i18n.py

• New language global setting (English, Español, Français, Deutsch, Italiano, Português, Nederlands, Türkçe).
• Localizes the calendar weekday headers + agenda labels and the weather "Updated / Feels Like / Wind / Humidity" labels.
• Add languages in core/i18n.py with three dicts (MONTHS, WEEKDAYS, LABELS).

Reflect-mode refresh — core/transitions.py + scheduler

• refresh_mode: "auto" (default) uses dirty-rect partial refresh when the panel supports it, with a full-refresh recharge every 20 partials.
• refresh_mode: "full" opt-out forces full-frame always (dashboard Display Transitions card).

Feature highlights

• Zero-browser rendering — vector canvas engine, resolution-independent layout, auto-scaling typography, fractional split boxes.
• Display auto-detection (v0.3.0) — driver: auto probes for a Pimoroni Inky panel; falls back to the virtual display if absent/headless. No manual model selection for standard panels.
• Community widget system — rndrsbc search | install | remove | list; artifacts are SHA-256 verified from the catalog feed and installed into the deploy home (never into site-packages).
• GPIO buttons — next / prev / quiet-toggle on GPIO 17 / 27 / 22; auto-disabled when RPi.GPIO is absent.
• CalDAV + iCal — calendar widget fetches private CalDAV (REPORT) or public iCal feeds; native ICS parser, no extra deps.
• i18n — English, Español, Français, Deutsch, Italiano, Português, Nederlands, Türkçe.
• Relocatable — anchors every path to its own folder; optional vendor/deps wheel bundle for fully-offline operation.

Releases & versioning

rndrsbc ships on PyPI and versions via Semantic Release driven by conventional commits:

• feat: → minor · fix: → patch · BREAKING/feat!: → major (on the 0.x line, breaking bumps the minor digit)
• Merging to main auto-bumps core/__init__.py, regenerates CHANGELOG.md, cuts the vX.Y.Z tag, and publishes to PyPI (publish.yml, trusted publishing / OIDC).
• Deploy-side state is never touched by an upgrade — pip install -U rndrsbc is the whole upgrade.

License

See LICENSE. Built as a clean-room implementation; all widget and driver code is original.

QA & Display Validation

The rest of this repo is rendering logic; this section is the prove-it-works loop. Run these on the Pi to confirm the panel reproduces the intended colours deterministically.

rndrsbc calibrate — push the reference colour pattern + verify primaries

Renders the canonical 7-colour test pattern (black/white/yellow/red/blue/green swatches + dither band + border frame), pushes it to the physical panel, and verifies each block is a true primary (software check before the panel fires). Saves calibration.png under /rool-drive so you can audit remotely.

sudo -E rndrsbc calibrate            # -> verdict OK/BLOCK-FAIL, block table
sudo -E rndrsbc calibrate --json     # machine-readable report

If a block reports FAIL, that channel's palette entry is wrong for the panel generation — fix the colour in core/calibrate.PRIMARIES (or the driver path) before trusting any widget render.

rndrsbc snapshot — capture the intended frame to a PNG (no panel)

Renders the current configured first playlist item exactly as the daemon would, and saves the pre-dither RGB canvas to /rool-drive/screen.png without touching the panel. This is your remote-verifiable ground truth: compare it against a photo of the panel to spot palette drift without a camera on the Pi.

sudo -E rndrsbc snapshot --out /rool-drive/screen.png

rndrsbc panel-spec — which panel is actually attached?

Reads the eeprom to say which Inky generation (Spectra 6 / 7-colour vs E6 / 4-colour) is on the SPI bus, plus its native palette. Confirms your driver targets the right colour set so a hardware swap surfaces as a boot-time mismatch, not mysteriously-off colours days later.

sudo -E rndrsbc panel-spec

Golden image regression (CI)

tests/test_qa_regression.py asserts (a) the colour pattern maps to exact native primaries, (b) render_preview() yields a deterministic 800×480 RGB frame, and (c) panel classification resolves the correct palette. Run:

python3 -m pytest tests/ -k qa

All four run under the same config → display wiring as the live daemon (core/qa.build_display), so the QA path and the production path can't diverge.