General > General Technical Chat
RE LCD Display
metrologist:
I've acquired a MODEL DE/280A Digital Electronics Corp display. These are out there but I have not found a communication protocol or pinout. I think mine is a little newer than the pictures here but same chips and labeling. That main chip, DE280A, is there any hope of figuring it out?
metrologist:
I found some info:
https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=1091816
The DE/280A accepts ASCII signals for
the normal upper and lower case 96-
character set and also for the expanded
set, which, includes Katakana and
selected ECMA characters. An on-board
microprocessor handles decoding,
character generation, display buffering,
cu,rsor control, auto flashing of any or
all characters, refresh, programmable
reset, self-test, and a blinking visible or
invisible cursor. All drive electronics
are included along with necessary
power conversion circuitry to adapt
incoming +5 Vdc to tube voltages.
Jumper selectable Bd rates (1200,2400,
and 4800) are available for serial interfacing. Parallel interface is also standard. RS-232 voltage levels are optional. All character positions are
randomly addressable. One additional
feature of the DE/280A is that it is the
same form, fit, and function as DECO's
single-line 40-character module, the
DE/245A. Consequently, either display
can be used in a design without any
changes in dimensions or user software.
DavidAlfa:
You could try reading the rom from the P8042AH.
Check the datasheet, the verification sequence is explained, although it's a bit scary :D
metrologist:
That seems like the smart way to start. I wasn't even smart enough to recognize the chip number but at least the datasheet gives me some ideas of where to look for data pins, where my approach would be to inject some random serial data, or think I've found the parallel data pins and load up the LiquidCrystal Arduino library and... of course that would never get anywhere, no chicken dinner.
I remember a video that Dave did on these vacuum displays though, and he figured out the data protocol. Wouldn't that be amazing if it was the same product? Unlikely, but I'll go look for his video. Otherwise, these are around the market and it seems a protocol could be found. I haven't found it.
metrologist:
Ah yes, here we go...maybe there is hope. At least I can still remember that I saw this seven years ago...
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