Where does he get such wonderful toys? [Glenn] snagged parts of a Grass Valley Kalypso 4-M/E video
mixer switcher control surface from eBay and since been reverse engineering the button and display modules to bend them to his will. The hardware dates back to the turn of the century and the two modules would have been laid out with up to a few dozen others to complete a video mixing switcher console.
[Glenn’s] previous adventures delved into a strip of ten backlit buttons and gives us a close look at each of the keyswitches and the technique he used to pull together his own pinout and schematic of that strip. But things get a lot hairier this time around. The long strip seen above is a “machine control plane” module and includes a dozen addressible character displays, driven by a combination of microcontrollers and FPGAs. The square panel is a “Crosspoint Switch Matrix” module include eight individual 32 x 32 LCDs drive by three dedicated ICs that can display in red, green, or amber.
[Glen] used an STM8 Nucleo 64 to interface with the panels and wrote a bit of code to help map out what each pin on each machine control plane connector might do. He was able to stream out some packets from the plane that changed as he pressed buttons, and ended up feeding back a brute-force of that packet format to figure out the LED display protocols.
But the LCDs on the crosspoint switch were a more difficult nut to crack. He ended up going back to the original source of the equipment (eBay) to get a working control unit that he could sniff. He laid out a man-in-the-middle board that has a connector on either side with a pin header in the middle for his logic analyzer. As with most LCDs, the secret sauce was the initialization sequence — an almost impossible thing to brute force, yet exceedingly simple to sniff when you have a working system. So far he has them running under USB control, and if you are lucky enough to have some of this gear in your parts box, [Glen] has painstakingly recorded all of the details you need to get them up and running.