This Large Raspberry Pi-Powered E Ink Calendar Ensures You'll Never Forget an Important Date Again

Designed to run without wires for 3-4 weeks, this smart calendar is a great low-power Internet of Things build.

Pseudonymous maker "speedyg0nz" has finished a smart, though pricey, build for keeping them up-to-date with their appointments: a large-format E Ink Magic Calendar, powered by a Raspberry Pi Zero W.

"Back in 2019, I started a thread in Reddit to bounce an idea I had with the community: To replicate the Android Magic Calendar concept that inspired many DIY projects in the subsequent years," speedyg0nz explains. "But specifically, I wanted it to run on battery so I could position it anywhere in house, and even hang it on the wall without a wire dangling beneath it. I also wanted the parts to be plug and play since I had neither the desire nor the steady hands needed to solder anything."

The resulting build is based on a large-format Waveshare 12.48" tri-color E Ink display, which is sunlight readable and requires power only when changing states — ideal for an infrequently-updated calendar display —connected to a Raspberry Pi Zero W with a PiSugar2 uninterruptible power supply with real-time clock, all without a single bit of hand soldering.

"Through PiSugar2's web interface, the onboard RTC can be set to wake and trigger the RPi to boot up daily at a time of your preference," speedyg0nz explains. "Upon boot, a cronjob on the RPi is triggered to run a Python script that fetches calendar events from Google Calendar for the next few weeks, and formats them into the desired layout before displaying it on the E Ink display. The RPi then shuts down to conserve battery."

Designed for wireless use, the calendar gets around 3-4 weeks of use per charge, while the tri-color display offers the ability to highlight events in red as well as the black and white of a usual E Ink panel. However, there's something which may stop people following in speedyg0nz footsteps despite the release of full source code for the project: Price.

"Honestly, the cost of this project is way too high for a single purpose device," speedyg0nz admits. "Personally, I've been looking at E Ink tablets that emulate the experience of writing on paper, and allow the users to take notes on the go. Those familiar with this range of products would be aware of the reMarkable tablet, Ratta Supernote, Kobo Elipsa and many others."

"My next project is likely to enhance one of these devices such that the calendar will be displayed when it's not in use. While this is usually possible by manually setting the sleep screen image/screensaver, I'm looking to have the screensaver updated automatically on a daily basis, like how it was done in this project."

The source code for the project is available on GitHub, along with a write-up detailing its origins and use, under the permissive Apache 2.0 license.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire:
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