Using a Custom PCB as a Live Transit Display
CharlieBoard uses a custom PCB as the display for a transit map that tracks Boston’s MBTA trains in real-time.
There are plenty of good display options for electronics projects, ranging from OLED to LED matrix to E Ink. However, when Thomas Underwood decided to build a real-time transit map, a more unconventional option was chosen — a PCB. This board has Boston’s MBTA Red Line and surrounding area silkscreened onto it. LEDs positioned along the track show the current position of the train, and the entire build is installed in a frame to make it look nice on a desk or coffee table.
The project, called CharlieBoard, is built around a Raspberry Pi Zero 2 W, which serves as the main controller and networking device. Addressable WS2812B LEDs are used for the display itself, either mounted on custom-designed PCBs or arranged as standard LED strips. Power is supplied by a 5V 4A adapter capable of running both the Pi and the LEDs, while a microSD card holds the operating system and application software. Builders can mount the finished display in anything from a simple picture frame to a fully custom enclosure. Depending on whether off-the-shelf LED strips or custom PCBs are used, total hardware costs typically fall between $50 and $180.
On the software side, CharlieBoard pulls live transit data directly from the MBTA’s public API. Once configured with an API key, the system continuously retrieves real-time information such as vehicle positions, speed, and occupancy. That data is then mapped to the physical layout of the LEDs, resulting in a geographically accurate visualization of trains moving along the line. The software runs automatically on boot and includes health monitoring and recovery features to keep the display operating reliably over long periods.
Control and customization are handled through a built-in web interface, accessible from any device on the local network. From there, users can adjust brightness, colors, and operating hours, or monitor system status.
Beyond the Red Line board shown in early builds, PCB designs for the MBTA’s Blue, Orange, and Green Lines are actively in development. All design files, including Gerber and KiCad sources, are available for others to modify or fabricate their own boards. You can grab everything from the GitHub repository.
R&D, creativity, and building the next big thing you never knew you wanted are my specialties.