Piinky is a calendar display for the fridge.

During COVID I built a little magnetic Waveshare e-ink weather gadget + Pi Zero W.

It still works well, but what if it had our family calendars on it? It'd need a bigger multi-color capable display.

Piinky was the answer and my winter break 2024 project.

Unfortunately, even the Raspberry Pi Zero 2 W is too RAM-limited to run the Chrome or Firefox headless drivers and load the React frontend using the Playwright screenshot package, so grab a Raspberry Pi 5 and feel the power.

(TODO: Try running the frontend with SSR to reduce the page complexity when loading it headless, and try again on the Zero 2 W)

(A Pi 4 or even a Pi 3B+ could probably handle the screenshots, but they are not what I had available.)

Download Raspberry Pi Imager and create an SD card image of the latest 64-bit OS with Desktop available. Would the Lite version work? Maybe, but the Desktop is foolproof. Also, be sure to set up your Wi-Fi network and a user in the Imager options.

Pimoroni makes a few different sized Inky displays, but the Inky Impression 7.3" one is the perfect size and shape for a multi-week calendar.

On your Pi, install the required packages and enable SPI:

# Enable SPI interface
sudo raspi-config nonint do_spi 0
sudo raspi-config nonint do_i2c 0

# Install required packages
sudo apt-get update
sudo apt-get install -y python3-pip python3-rpi.gpio python3-spidev python3-pil python3-numpy

Edit your config.txt file to enable SPI:

sudo vi /boot/firmware/config.txt

# Add this line near the bottom of the file:
dtoverlay=spi0-0cs

Now reboot your Pi:

sudo reboot

Log in again and set up your development environment:

cd ~
mkdir dev
cd dev
git clone https://github.com/coreyk/piinky.git
cd piinky

1. Open Google Cloud Console
2. Selected an existing project, or create a new project for Piinky
3. Open APIs & Services > Credentials
4. Under Service Accounts click Manage Service Accounts
5. Add a new service account by clicking + Create Service Account in the header nav
6. Under Service Account Details, name it piinky or something memorable, skip to the bottom and click Done (not Create and Continue)
7. Click the Service Account just created, go to the Keys tab, click Add Key > Create new key
8. Select the JSON Key type and click Create
9. The JSON key file will be downloaded
10. Move and rename the JSON file to ~/dev/piinky/google_credentials.json

1. Open Google Calendar
2. In the sidebar, click Options > Settings and sharing for a calendar you want to use with Piinky
3. Under Share with specific people or groups click + Add people and groups
4. Start typing the name of the Service Account you just created and autocomplete will display it. The account email should end in .iam.gserviceaccount.com
5. Select See all event details under Permissions and click Send
6. Scroll down to Integrate Calendar and find the the Calendar ID (we'll come back to it in the next section)

1. Copy ~/dev/piinky/google_calendar_config.json.example to ~/dev/piinky/google_calendar_config.json and edit it
2. Copy the Calendar ID from the previous step and paste it into one of the calendar_id values
3. Optionally, pick a new color from the colorMap in ~/dev/piinky/frontend/src/lib/colormap.ts

1. If you have a split municipal recycling pickup schedule for cardboard and cans/plastic like I do, find it and if they have a PDF, download it. Note your trash pickup schedule, too.
2. Using Claude AI or your file upload-capable LLM of choice, upload the calendar PDF and ask it to create an .ical file with all-day events with a prompt like:

Create an iCal or other importable file for Google Calendar based on this PDF of recycling collection days. If the icon on Wednesday is a bundle of newspapers, create an all-day event titled "Cardboard". If the icon on Wednesday is a bucket of bottles, create an all-day event titled "Cans". Add an all-day event every Tuesday and Friday titled "Trash", as well.

3. Alternatively, if you don't have a calendar PDF, just prompt it to create an .ical file based on your schedule of Cans, Cardboard, and Trash.

1. Create an OpenWeatherMap account
2. Go to your API keys page
3. Generate a new API key for the 3.0 API
4. Copy the key and add it to your configuration file: ~/dev/piinky/owm_config.json

Note: You'll have to enter billing info but you get 1000 requests per day for free, which is more than enough for Piinky.

Install Node.js 23.x on the Raspberry Pi:

# Add NodeSource repository
sudo apt-get update
sudo apt-get install -y ca-certificates curl gnupg
sudo mkdir -p /etc/apt/keyrings
curl -fsSL https://deb.nodesource.com/gpgkey/nodesource-repo.gpg.key | sudo gpg --dearmor -o /etc/apt/keyrings/nodesource.gpg
echo "deb [signed-by=/etc/apt/keyrings/nodesource.gpg] https://deb.nodesource.com/node_23.x nodistro main" | sudo tee /etc/apt/sources.list.d/nodesource.list

# Install Node.js
sudo apt-get update
sudo apt-get install -y nodejs

# Install frontend dependencies
cd frontend
npm install

Install Go on the Raspberry Pi:

cd ~/dev
# Download Go
wget https://go.dev/dl/go1.23.4.linux-arm64.tar.gz

# Install Go
sudo tar -C /usr/local -xzf go1.23.4.linux-arm64.tar.gz

# Add Go to your path (add to .zshrc, .bashrc, or .profile)
echo 'export PATH=$PATH:/usr/local/go/bin' >> ~/.profile
echo 'export PATH=$PATH:$(go env GOPATH)/bin' >> ~/.profile
source ~/.profile

# Install backend dependencies
cd backend-go
go mod tidy

cd ~/dev/piinky
./piinky.sh --create-env backend-go
cd backend-go
go test ./... -v

Install Playwright and other dependencies:

cd ~/dev/piinky/display

# Install Python dependencies
python3 -m venv venv
source venv/bin/activate
pip install -e .

# Install Playwright browser drivers
playwright install
playwright install-deps

# Install emoji font for recycling icons
sudo apt install fonts-noto-color-emoji

The tests will only run on a Raspberry Pi with the Inky display, due to the inky dependency.

cd ~/dev/piinky/display
pip install -e ".[test]"
pytest -v

If you want to use the Python backend instead of Go:

cd ~/dev/piinky
./piinky.sh --create-env backend
cd backend
python -m venv venv
source venv/bin/activate
pip install -e .

cd ~/dev/piinky/backend
pip install -e ".[test]"
pytest -v

# For test coverage
pytest --cov=. tests/

My idea was to try out the experimental Inky Impression library on Google periph.io but the 7.3" Inky I'm using only has an unmerged PR which I haven't been able to get working.

Install Piinky as a system service:

cd ~/dev/piinky

# Copy service file
sudo cp service/piinky.service /etc/systemd/system/

# Reload systemd
sudo systemctl daemon-reload

# Enable service to start on boot
sudo systemctl enable piinky.service

# Start the service
sudo systemctl start piinky.service

# Check status
sudo systemctl status piinky.service

# View logs if needed
journalctl -u piinky.service

The case is available on Printables. Download the scad-utils and drop it in the same folder as the case file.

Since it's an OpenSCAD file, you can modify it to your liking as I did to add depth for the Pi 5, ventilation, and a slot for the USB-C power cable.

It's a remix of this Inky Display Frame which is made for the shallower Pi Zero W.

I also made a 3D printed USB-C power cable holder to keep the cable stuck to the fridge. It uses the same magnets as the case.