from Raspberry Pi Blog – Raspberry Pi
Author Ashley Whittaker
James Bruxton (or
@xrobotosuk on Instagram) built an IoT-controlled e-paper message board using Raspberry Pi. Updating it is easy: just edit a Google sheet, and the message board will update with the new data.
Harnessing Google power
This smart message board uses e-paper, which has very low power consumption. Combining this with the Google Docs API (which allows you to write code to read and write to Google Docs) and Raspberry Pi makes it possible to build a message board that polls a Google Sheet and updates whenever there’s new data. This guide helped James write the Google Docs API code.
James’s original plan was to hook up his Raspberry Pi to a standard monitor and use Google Docs so people could update the display via mobile app. However, a standard monitor consumes a lot of power, due to its backlight, and if you set it to go into sleep mode, people would just walk past it and not see updates to the list unless they remember to wake the device up.
Enter e-paper (the same stuff used for Kindle devices), which only consumes power when it’s updating. Once you’ve got the info you want on the e-paper, you can even disconnect it entirely from your power source and the screen will still display whatever the least update told it to. James’s top tip for your project: go for the smallest e-paper display possible, as those things are expensive. He went with this one, which comes with a HAT for Raspberry Pi and a ribbon cable to connect the two.
The HAT has an adaptor for plugging into the Raspberry Pi GPIO pins, and a breakout header for the SPI pins. James found it’s not as simple as enabling the SPI on his Raspberry Pi and the e-paper display springing to life: you need a bit of code to enable the SPI display to act as the main display for the Raspberry Pi. Luckily, the code for this is on the wiki of Waveshare, the producer of HAT and display James used for this project.
Making it pretty
A 3D-printed case, which looks like a classic photo frame but with a hefty in-built stand to hold it up and provide enough space for the Raspberry Pi to sit on, is home to James’s finished smart to-do list. The e-paper is so light and thin it can just be sticky-taped into the frame.
Extra points for this maker, as he’s put all the CAD files and code you’ll need to make your own e-paper message board on GitHub.
If you’re into e-paper stuff but are wedded to your handwritten to-do lists, then why not try building this super slow movie player instead? The blog squad went *nuts* for it when we posted it last month.