Connecting an LED Sign to the Internet

LED matrix sign and browser screenshot showing how the text form used to display something on the LED display

This was a quick-and-dirty one day project. I got my hands on some old RS485 LED signs (like those found in hospital hallways) and I wanted to do something with them.

I used a Raspberry Pi Zero W with an off-the-shelf RS485 daughterboard to connect the LED panel. Kindly enough, the manufacturer sent me the PDF specification of the serial protocol the displays use, so it was really easy to get something displayed.

I wrote a Python script that takes the string to be displayed, encapsulates it as specified by the display protocol and sends it to the LED panel via the RS485 hardware.

This Python script gets run as a CGI script by an Apache webserver which is also running on the Pi, which allows for convenient remote control via HTTP POST.

In the future I might add a CO2 sensor for air quality monitoring or allow the user to select a wall clock mode (the displays actually already contain an RTC!)