InkyImpression

Display server for a 13.3" Pimoroni Inky Impression on a Raspberry Pi Zero 2 W.

Hardware

• Display: Inky Impression 13.3" — 1600×1200, 6 colors (Spectra 6: red/green/blue/yellow/black/white), ~12s refresh (real-world 20–35s).
• Host: Raspberry Pi Zero 2 W (quad-core ARMv7, 512 MB RAM — enough for headless Chromium on a single page).
• Buttons: 4 tactile buttons on the back. For the 13.3" variant they map to BCM GPIO 5, 6, 25, 24 (note: 25, not 16 — see reference/inky/examples/spectra6/buttons.py).
• Mounting: Pi Zero plugs straight into the socket header on the back. USB ports face down; text on Pi and Inky reads the same way up. Power off before attaching/removing.

What this project does

Drives the Inky Impression to cycle through display "scenes":

1. Tasks — pulled from the webapp tasks module (~/dev/webapp/src/modules/tasks).
2. Restaurant menu — shown during the lunch window (12:00–13:00).
3. Announcements / events — cycled via the 4 hardware buttons.

Architecture

Current strategy (this branch): headless Chromium on the Pi.

The webapp already renders the scenes we want (tasks.ariege.io, etc.), so the Pi runs chromium --headless --screenshot against the live URL, then pushes the PNG through PIL into the inky library. E-ink refresh is 20–35 s anyway, so a 5–15 s screenshot is comfortably within budget. Inky's set_image() handles dithering to the 6-color Spectra 6 palette.

Other strategies we may try on branches later:

• Webapp JSON → PIL: lighter, no browser, but layouts have to be redrawn by hand.
• External render service: only worth it if multiple Pis share renders, or if Chromium-on-Pi proves too slow/flaky.

Initial Pi setup

Flash Raspberry Pi OS Bookworm or later (the "with desktop" image is recommended by Pimoroni — pulls in the dependencies, but Lite works if you install them manually).

On first boot:

sudo raspi-config
# Interfacing Options → enable SPI and I2C
sudo apt update && sudo apt upgrade -y
sudo apt install -y git python3-venv python3-pip chromium
# On older Raspberry Pi OS (Bookworm and earlier) the package is named chromium-browser instead.

Install the Inky library via Pimoroni's installer (creates ~/.virtualenvs/pimoroni):

git clone https://github.com/pimoroni/inky
cd inky
./install.sh
source ~/.virtualenvs/pimoroni/bin/activate

Verify the display is detected:

python3 -c "from inky.auto import auto; i = auto(verbose=True); print(i.resolution, i.colour)"

Quick smoke test using the bundled example:

cd ~/inky/examples/spectra6
python3 image.py --file images/spectra6-1600x1200.png

Then clone this repo on the Pi and install into the same venv:

git clone <this-repo-url> ~/InkyImpression
cd ~/InkyImpression
pip install -e .
inky-impression          # runs the main loop

Project layout

.
├── README.md
├── pyproject.toml
├── src/inky_impression/
│   ├── __init__.py
│   ├── __main__.py     # `python -m inky_impression`
│   ├── main.py         # scheduler loop
│   ├── render.py       # chromium screenshot → PIL → Inky
│   └── scenes.py       # which URL to show at what time
└── reference/inky/     # cloned Pimoroni library (gitignored)

Reference

• Pimoroni library (cloned for reference): reference/inky/
  • inky/inky_el133uf1.py — driver for the 13.3" Spectra 6 panel
  • examples/spectra6/image.py — minimal "draw an image" example
  • examples/spectra6/buttons.py — button GPIO setup (remember: SW_C = 25 for 13.3")
• Pimoroni getting-started article
• Webapp tasks module: ~/dev/webapp/src/modules/tasks

Version control

This repo uses jj (colocated with git):

jj st          # status
jj describe    # set commit message for working copy
jj new         # start a new change