Teensy 2.0 + HCMS2975

The components used to construct the Teensy 2.0-based HCMS-2975 displaySo here’s another part of my endeavour to put left-over components from previous projects to good use, and again it’s got something to do with LEDs. This time, I set out to make an eight character 7×5 pixel LED display of type HCMS-2975 controllable from my computer. As I usually keep a batch of Teensy 2.0 available for such purposes, getting it done was a comparably quick job. No external components are needed when connecting these two devices, so it boiled down to connecting just five data pins and the supply voltage. I used Eagle to design a PCB (using the Teensy library from here and the display library – which I had to slightly modify to support the display with eight characters – from here).

The HCMS-2975 soldered onto the designed PCB with the Teensy on the back.As the resulting board was less than 1″x2″ in size, I decided to give Seeed Studio’s Fusion PCB service a try this time. Fusion PCB does not accept Eagle files, but provides an Eagle to Gerber converter job, which completed without any problems. After slightly more than 2 weeks of waiting, the PCBs had already arrived by airmail. Although one board would have been enough for me, Fusion PCB only sells batches of 5 PCBs at a time, and eventually even delivered seven boards (drop me a line if you want one). For a price tag of around $2 per board, the quality is remarkably good – only on one board the vias didn’t align very well.

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