I have a working, still accurate, good ol' HP 3478a that runs/ran like a champ...until it's LCD display kicked the bucket. One or both of the epoxy blob ICs are definitely fried...they can't even properly generate the AC bias to refresh the LCD, so you see one half of the screen briefly come on, fade to nothing from being DC biased too long, then another flicker of life in a second or 2. But, even what is displayed is gibberish.
I found in this
thread that the HP 3488a is a good, cheap source of a replacement display, but where's the fun in that? What if I want to hook up a hot and power hungry VFD? Or a giant 1 foot by 16 foot LED wall display of death? Or just pipe it into a character or graphic OLED screen? What if I want the display to be....nicer!
Well, that requires decoding the gibberish the CPU is using to control this unknown display controller. Unfortunately, I am not very strong when it comes to digital protocols, and don't really know what to make of this. Does anyone have any hints, ideas, possibilities, in regards to this digital capture?
I've captured several seconds and display refreshes worth of bit nuggets (or whatever) using a Saleae logic analyzer. I know this kind of amounts to me asking someone to do my work for me, but I really have no clue. At least a little guidance would be helpful =). But I've attached a screen shot as well as the actual capture in both per-sample 8-bit binary and .logicdata format. I can export other formats if needed. Be warned, the .bin unzips to something like a 180MB file.
I've tried using the built in analyzers to little effect. The 1 and 2 lines also have exactly the same data at all times, though 2 is delayed ever so slightly from 1. They seem to be going around 39KHz, which makes me wonder if they're 38400 Asychronous serial lines. But why 2 lines of the same information?
Really, all I want is to figure out what digits/letters/segments the HP 3478a is wanting to be light up, and with that knowledge + any basic µC, a wonderland of display hacks is opened up (I mean some straight Aladdin and Jasmine 'Whole New World' magic carpet shit).
if anyone recognizes or otherwise notices anything useful, I would be very much appreciative for a reply. And I'm sure this will be a helpful resource to anyone with an hp3478a =).
