46 pin (2x23) LCD interface

[TomS_]

Hi all.

Im tearing down an old Cisco IP phone that Ive had forever but which I no longer use (7940G). I thought I'd see if there was anything interesting/useful inside it that might make for a rainy day project some time.

Maybe about the only interesting thing so far (its full of ASICs, of course) is the LCD, but it has an interface that Ive not come across before.

Im wondering if anyone might happen to know if this fits some kind of standard or common interface, and/or whether there is a datasheet floating around somewhere that would detail how to drive the LCD itself?

I figure I might try to build a breakout board for it so that I could potentially use it in a project, or just muck about with it.

It appears to have an 8 bit interface that I traced to the 74FCT3573 which is right at the bottom of the photo. From there it then disappears into a Cisco branded ASIC of some kind (possibly just a branded FPGA, Ive seen them do this in other products).

Thanks!

[mariush]

Googling that part number umsh- ... shows the display is sold on ebay for around $200 ... and it's also stocked by some websites as spare part, and they also list  part number 700-05023-01 for it.

May want to try searching for other part numbers that start with umsh- on sites that have catalogues of datasheet pdfs
For example found  ̨UMSH-7115 datasheet with has a 39 pin connection , with a few of them being led backlight: https://datasheetspdf.com/pdf-file/611933/URT/UMSH-7511MD-5T/1

[TomS_]

Thanks. I had a look at all of the similar datasheets there, but they are all either for an RGB display that looks to have a very different interface or have much smaller buses on them (maybe serial?).

I did try emailing the manufacturer but predictably have had no response.

[coromonadalix]

since you have cisco logo, it could be a custom design too


 the best luck  would be to search all the main ic's on the  pcb  to see the lcd controller etc ...

[TomS_]

I traced a bunch of signals (what is probably a data bus) into a Cisco branded chip. It could be an FPGA, but since it only has a Cisco part number on it, it's not possible to find any information about it other than some people selling "replacements".

It could end up being something that I need to probe during operation and reverse engineer that way. A datasheet saving that effort would be nice though. :-)

[TomS_]

since you have cisco logo, it could be a custom design too


 the best luck  would be to search all the main ic's on the  pcb  to see the lcd controller etc ...

Actually, on that note, I believe I saw it has driver chips on the flex (chip on flex job). I'll see if they have any markings that might give up some secrets.

They are wrapped up under some tape so I'll need to cut that off carefully first.

Looking at some of the other datasheets it would seem likely that it has a very Hitachi style interface, so if I can figure out what some of the pins are it might not be too hard to get it working. The left side looks very analogue so may be various voltage rails and some decoupling caps or some such, while the right hand side looks decidedly much more digital.