This low-power ePaper display automatically joins a long-range wireless network and displays weather information, along with arbitrary data entered from the browser interface. Messages are automated for regular updates from a NodeJS/React server. In the pictured example, a school schedule is shown, along with air quality, (from this project), stock price, and and swimming pool data.
This turns out to have been a fairly simple project to put together. It required designing a driver board for the Waveshare 2-color 5.9" ePaper display, writing a bit of firmware and creating a 3D-printed enclosure. Some interesting aspects have been
- Using a TrueType utility I'd created for this LED panel project and storing font data in external flash memory
- Having to figure out how to draw the entire screen (648x480) with very limited RAM (drawing blocks one line at a time). That was a little tricky in terms of bit alignment. Might document the approach I used more specifically at a later time.
In my original design, I hadn't thought to add a way to measure the battery, so I added a resistor divider bodge feeding into an ADC on the CC1312:
And in closing:
The battery will last months on a single charge, but if I redid this project, I'd opt for a black & white version. The red & black version takes multiple seconds to update, consuming milliamps of current while doing so. The black & white version updates in less than a second, which would lead to many years on even a small lipo battery.