Thursday, July 9, 2020

Building an Election Calendar on the Raspberry Pi 4 using DisplayIO @Adafruit @CircuitPython @Raspberry_Pi #Blinka, #PyPortal #DisplayIO

Recently a new learn guide came out on building an Election Calendar on the PyPortal. Since I have been working on adding PyPortal support on the Raspberry Pi and other single board computers along with Displayio support, I thought this would be an excellent project to try out. It turns out that it was really easy to get up and running. The benefit of having a project like this is that it makes it easy to keep up with specific election related deadlines for your location, so that you can make sure you are able to vote and be heard.

First of all, the calendar isn’t actually running on the PyPortal itself. This is actually going out to https://electioncal.us and getting the information from there, which is returned in a JSON or JavaScript Object Notation format. The PyPortal parses the information and displays it for you. The Blinka PyPortal library, which is the analog to the CircuitPython PyPortal library that runs over Blinka, is able to leverage both the existing network connection of the Raspberry Pi and the huge number of libraries available over CPython.

The only things I have connected to my Raspberry Pi 4, in addition to an aluminum heatsink case and 40-pin stacking header, are a 3.2″ PiTFT and a Monoprice 5W amplified speaker connected through the 3.5mm audio output of the Pi. You can pick up all of these items in the Adafruit shop.

To get it working, I started by downloading all of the project files and uploading those to the Raspberry Pi over SFTP, which was easy enough. Then I took the code and replaced the line that determines the Current Working Directory and altered that to work in CPython. If you’re interested in the specifics of the change, you can see the same change was made in the rest of the Blinka Pyportal Examples. Additionally, since there is no status Neopixel on the Raspberry Pi, I removed that parameter from the PyPortal initialization function. I also changed my state and county so that it would give me relevant information.

As for the specific dependencies, I already had my libraries set up from testing out the PyPortal library, so once I fired it up the script, it just ran. I’m currently working on a guide on the specifics of how to set up a Raspberry Pi to run the PyPortal library. It should be ready in the next day or two, so be sure to keep an eye on the Adafruit blog or you can view the latest Adafruit Learn Guides.

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