I got an Inky Impression and after I got done putting Silver Age comic panels on it, I thought it might make a nice clock.

Installing it

From a box-fresh install of Raspberry Pi OS Lite via NOOBS 3.5:

Enable SSH

Login on the Pi's console and

sudo raspi-config nonint do_ssh 0

You should now be able to get on to the Pi with

ssh pi@raspberrypi.local

Install the software

You need git:

sudo apt-get install -y git

Then clone this repo:

git clone https://github.com/pikesley/impression-clock

and configure everything:

cd impression-clock
make setup

Optionally, change the hostname

sudo raspi-config nonint do_hostname impression

Now reboot, and the clock should start showing you the time

sudo reboot

Hacking on it

There's a Docker image. Build it:

make build

and run it:

make run

Inside the container, the default make target will run the the linter and the tests:

make

Design

Most of the easily-tweakable things are in conf/conf.yaml:

Fonts

You can (independently) change the fonts for the time and date strings - download a TrueType font into fonts (Google have some nice ones), then put its exact name (less the .ttf extension) in the font.family field. You can also set its point-size in the size field.

offset

The offset is the y-position of the text (I think), but I don't understand why different fonts require wildly different values to achieve a similar layout - I'm not sure what it's offsetting, or what it's offsetting from. Maybe somebody who understands this stuff better than me might be able to explain what's going on.

As it is, I just tried various numbers until it looked OK. Which brings me to

Testing the layout

There's a special test which generates a sample clockface using 00:00 for the time and 22nd September for the date (which, by my reckoning, are just about the widest strings the clock has to deal with), and drops it in tmp/test-font-size.png. This provides a handy guide as you're tweaking the size and offset values. And also

Images

The clock generates the display using whatever is defined in images.background as its background image, and then images.foreground as a mask for the time and date strings (this basically means it fills in the text with the relevant parts of that image) - these images need to be 600x448 pixels, and placed in backgrounds.

By default, this gives black text on a white background, but you can put anything you want in there - using a photo for background, then a colour-inverted copy of that image for text works quite well.

I believe it may work nicely using whatever you might turn up with an image-search for silver age x-men panel but I cannot recommend doing this.

Tests

Note that changing any of this stuff will cause the tests to fail - the expectations are sha256-hashes of the generated images. If you care, you should verify that the images generated at tmp/clock.png look correct, then copy the hashes from the test failures into the checksums dict in tests/test_clockface.py.

Hardware

It's running on a Pi Zero W with a 15-minute load-average of about 0.17 - this is a very undemanding application.

Making the stand

I attached some Nimuno Loops / Makya Tape to the back of the screen:

And then made a stand out of Lego: