Reverse Engineering A Huge LED Display

muchosLEDs
In a fit of awesome salvaging, [Piet] picked up a huge, 16 character, 2 line display. It’s monstrous, designed for outdoor installations; road signs, train stations, and the like. It also draws 23 Watts¬†when nothing is being displayed,¬†making this the perfect piece of salvaged equipment to reverse engineer.

The display was originally connected to a computer running proprietary software. The protocol between the display and computer is also proprietary, giving [Piet] the choice of either reverse engineering the protocol, or reverse engineering the hardware and building a new driver board. For anyone with a soldering iron, the second option is the simplest.

Disassembling the display, [Piet] found each character in the display was its own board with a 7×14 array of pixels, each with four LEDs. The rows and columns of each character are addressed with a shift register, and with an Arduino, [Peit] got a single character working.

The Arduino would struggle to display all the characters in the display, so a Raspi was pulled out, a driver and frame generator written, and the whole thing connected to Twitter It’s a beautifully display that draws 200 Watts when its scanning the pixels, and a wonderful reuse of disused hardware. Video below.

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