Reddit user Beaverknighterino said he was “fascinated with E-paper projects so I finally decided to make one for my work calendar.”
The materials Beaverknighterino used are as such:
- Waveshare 7.5” B/W 800×480 E-paper
- Raspberry Pi Zero W
- Xiaomi 10000mAH Power bank
- IKEA HOVSTA Picture frame
Beaverknighterino mentioned that the project was made a bit more difficult because the work calendar uses CalDAV and many open source libraries support Google or iCloud only.
As of now, the system currently only gets less than five days of battery life before it shuts down. However, this is also the result of an unoptimized code, which Beaverknighterino says will be the target for improvement in the next iteration.
e-Ink displays are very power efficient because most of the power consumption happens when the display is refreshed with new content. Once the content is set, power consumption falls to zero.
The issue here is that the Pi Zero W is kept running in order to refresh the display after every meeting appointment and at midnight.
Here’s another project that uses the Raspberry Pi Zero.
Unlike the calendar above that’s powered by a battery pack, this is powered by USB, so there’s no issue with battery life.
The discussion surrounding the clock is probably the most interesting. One pertinent question is whether an e-ink display is capable of showing seconds. Here’s an important video:
Inherent to the weakness of an e-ink display is its one-second refresh time. This makes it very disruptive if you had to refresh every second and might not be conducive. But that’s the price for an ultra-efficient display.
Yet another interesting discussion is whether or not the Raspberry Pi Pico would be a good substitute for a Pi Zero, given that it’s cheaper and much easier to find in stock.
The conclusion was that, yes, you could… but….
But the issue is that the Pico doesn’t have the same features of the Pi Zero. Thus, you will need to add on a few modules — either a real time clock module or something that gives it internet access.
Not that the Pi Zero has a real time clock on board, but at least you get WiFi (with the Zero W variant). So, in essence, the Zero is overkill but it’s convenient.
- Install pi lite with no GUI on it
- Install python3 and tmux on it using SSH
- Follow all the instructions from here to install the libraries and examples to setup the eink display
- Create a new folder in the folder you downloaded from waveshare (where the lib, examples, etc folders are) and copy my code there
- Create a tmux session so that the script can run indefinitely in the background and start it with python3 (path to code) and exit the tmux session
Note: this code is specifically for a Waveshare 2.13 inch display V2, it is quite easy to switch out between versions, you just need to run each example until one works (that has the same resolution as the e-ink you have), I will make a proper tutorial and clean up the code soon.
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