Building a E-Ink based dashboard which would keep track of my meetings among other things. Given the always-on nature of the E-Ink display, this would help me better manage by schedule during a typical work-day especially given I tend to miss Google Calendar notifications a lot.
I took an off-the-shelf approach for the hardware. I purchased an InkPlate 6 which was originally crowd-funded on CrowdSupply.
The E-Ink display is from a recycled Kindle e-reader, which means its a pretty great display. It has 2 modes including a 2-bit per pixel gray-scale mode and monochrome. It supports partial updates in monochrome mode. The display is connected to a ESP 32, with built-in WiFi. All we need to do is to hookup the display to a PC via a USB cable and power it on. The display also comes with a nice 3D printed enclosure.
The InkPlate 6 supports MicroPython, and recently the libraries powering the display were opensourced. This gave me a decent foundation to build on top-of.
The first step to showing events from Google Calendar is to be able to complete an OAuth2 flow. I decided to use the device flow given the limited input capabilities of the ESP 32.
MicroPython does not have any libraries that work with OAuth2, so I decided to write one. Here is the PR that I eventually made to the micropython-lib GitHub repo which adds support for this specification. This ended up being pretty straightforward, given my familiarity with OAuth2 (having authored this library before).
The InkPlate has a decent Graphics API, but rather than having to hard-code coordinates to render UI i decided to take minor detour and build a mini UI Toolkit from first principles based on the graphics primitives that were supported. I took a lot of inspiration from the existing Android UI View system and build a small subset of those APIs.
Eink, E-paper, Think Ink – Collin shares six segments pondering the unusual low-power display technology that somehow still seems a bit sci-fi – http://adafruit.com/thinkink
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