Wednesday, August 27, 2014

Rescuing an Old System with Semicustom Firmware

Success! Modified firmware revives legacy system. 
A customer recently presented us with a common problem: He needed new serial displays for an old system. The catch was that the new displays had to perfectly emulate the old, long-discontinued displays because the legacy system could not be reprogrammed.

He had auditioned several currently available serial displays with varying success. Our GLO-216Y was the best display overall, but its instruction set didn't match the existing setup. Could I help?

I could. My tech contacted the manufacturer of the original display and got specs for the serial interface (an Apollo Displays CDSxxxC-1, where the xxx is commonly replaced with an Optrex part number, like CDS162C-1/16207N-B). The customer gave us a data dump of the serial stream going to the legacy display. The instructions were similar to our oldest serial displays, the BPI- series. In order to avoid stranding our longterm customers, I had written a version of our GLO- firmware that emulates an older serial LCD; this was promptly modified to match the CDSxxxC-1 specs.

Moment of truth: I fed the customer's data dump into the modified GLO-216Y. Up popped the old system's startup sequence, perfectly formatted. Woohoo! We can now upgrade a legacy system designed for mid-1990s LCDs with state-of-the-art OLEDs.

If you've never been caught out by a discontinued or obsolete product and a looming deadline or other nasty constraints (e.g., no program changes, ever), count yourself lucky. But if you do find yourself in a jam, maybe I can help. Let me know (

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