Round LCDs Put To Work In Rack Mount Gauge Cluster

ByPhyllis R. Edwards

May 14, 2022 , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,


Like many of you, we’re intrigued by the possibilities offered by the availability of affordable round LCD panels. But beyond the smartwatches they were designed for, it’s not always easy to come up with an appropriate application for such non-traditional displays. Digital “steam gauges” are one of the first ideas that come to mind, so it’s perhaps no surprise that’s the direction [Tom Dowad] took his project. But rather than just one or two gauges, he decided to go all out and put eight of them in a 1U rack mountable unit.

What do you need eight faux-analog gauges for? Beats us, but that’s not our department. Now [Tom] has a whole row of indicators that can be used to show whatever it is he likes to keep an eye on. The fact that the device is actually controlled via MIDI may provide us a clue that there’s a musical component at play (no pun intended), but then, it wouldn’t be the first time we’d seen MIDI used simply as a convenient and well supported way of synchronizing gadgets.

Beyond the eight 240 x 240 pixel panels, the unit features a Teensy 4.0, some level shifters, and a 74HC138 which is used to select which display the microcontroller is to communicate with. On the software side he’s using the Arduino environment with some PNG decompression routines lifted from [Larry Bank] and graphics code from [moononournation]. The background image of the gauge is apparently a licensed stock photo, which might seem a bit extravagant, but we can’t deny the final result looks very realistic.

Just last year we covered a primer on working with round LCDs, and we’ve already seen some enterprising hackers using them in custom smartwatches. Whether you’re suffering from aichmophobia, or just sick of being limited to the same boring displays in your gadgets, it’s exciting to see the community embracing this new technology.


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