Scrolling Character Matrix PCB

Earlier this year, we featured a matrix display from David Johnson-Davies, which uses an ATtiny85 to display characters scrolling across four 8x8 screens on a breadboard. While this was a neat bit of assemble-it-yourself hardware hacking, its breadboard substrate meant that it wasn’t very robust, and that components can fall off when dropped.

This new Scrolling Text Display PCB, as outlined here on DJD’s Technoblogy project site, is largely the same in terms of circuitry, but it’s designed so that it can be built by a parent or teenager with basic soldering skills. With its ATtiny85 microcontroller, display modules, and other components soldered on, a short drop or jostle is less likely to mean scouring the floor for parts to reassemble.

The new PCB has holders for three AAA batteries, which, in addition to powering the device, also hold it at an angle for easy viewing. It has solder pads to reverse the order of VCC and GND for the displays as needed. The revised device even includes several firmware improvements, such as the inclusion of 26 pre-defined picture symbols, each of which can be modified via keyboard commands.

The original inspiration for this build was so that a friend’s seven-year-old son could use it in applications like model train stations. However, it’s been incorporated into other projects like stories, plays, and even a vending machine built from a cardboard box. One would have to assume there was some breadboard reassembly and troubleshooting involved in this process, so a more robust PCB design certainly makes sense. You never know where inspiration will strike, especially when you’re working with a junior collaborator!