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Edit: I wrote a mail to Sitronix asking for docs for this controller, and they said it is ST7522, with public avalible docs.

I'm currently trying to reverse engineer a device with an MCU, LCD, and an LCD controller in an epoxy blob. While trying to identify the LCD controller I removed some epoxy from the top and revealed a die with ST7523-08 marking.

Unfortunately searching for such controller in google didn't bring any results, so if someone could help me find docs or anything else about this controller it would be truly amazing, thank you!

P.S.: I'm also attaching the photos of the die.

Edit: To precise a bit more the device has an LCD with mostly characters and a grid of 55x7 pixels, so total of around 540 pixels(see the 1st photo).

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    \$\begingroup\$ LCD controllers are usually pretty generic. You'd likely be better off just analyzing how it connects to the outside world and comparing that to whatever controllers and protocols you can find. \$\endgroup\$
    – Klas-Kenny
    Commented Feb 3 at 17:01
  • \$\begingroup\$ What kind of LCD does it control, character or graphics? resolution? \$\endgroup\$
    – Rodo
    Commented Feb 3 at 18:58
  • \$\begingroup\$ @Rodo I added to the question details about the LCD. \$\endgroup\$
    – vorobey
    Commented Feb 3 at 22:00
  • \$\begingroup\$ What is your final goal? Do you need to replace it? Now that you "disclosed" the chip, some of its bonding wires are probably removed. Does it still work? \$\endgroup\$
    – the busybee
    Commented Feb 4 at 7:37
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    \$\begingroup\$ Very good photos by the way! \$\endgroup\$
    – winny
    Commented Feb 5 at 13:20

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These controllers are made by the company Sitronix. They have a line of similarly-numbered parts. It is possible that many of the parts use a similar protocol. I'd say, looking at your board, you may be able to determine which connections carry the protocol, and you could watch the signals to work out how it's being operated. Lower resolution displays almost always use a serial protocol like SPI or I2C.

I took another look at your photos and realized that the thing you circled was the part number marking you said that you saw on the die.

enter image description here

Upon closer inspecion, it looks like the part may be ST7529, in which case your problem is essentially solved, as there are data sheets for that part.

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    \$\begingroup\$ I think it reads ST7523, not ST7529, so the problem is not solved. \$\endgroup\$
    – Justme
    Commented Feb 4 at 20:33
  • \$\begingroup\$ Good take on the fact that it is a Sitronix controller. I tried comparing the one that I have to the existing controllers, but the thing that's bothering me is the physical size, that doesn't match to any controllers from Sitronix that I looked upon. However according to the PCB I'm pretty confident the protocol is 4-wire SPI so I guess I'll mark the question as answered. Thanks for your help! \$\endgroup\$
    – vorobey
    Commented Feb 5 at 1:01
  • \$\begingroup\$ I asked Sitronix about the controller, and they said it is ST7522, so case closed. \$\endgroup\$
    – vorobey
    Commented Feb 5 at 8:56
  • \$\begingroup\$ Does that number really not match the chip, or did you mean ST7523? And did those nice people send you a data sheet for your trouble? It's good to know they respond to inquiries! \$\endgroup\$
    – gbarry
    Commented Feb 5 at 16:07
  • \$\begingroup\$ @gbarry Apparently indeed it does not match and I have no clue why. It was surprising for me as well that they responded and even sent me the datasheet, but it is also available online. \$\endgroup\$
    – vorobey
    Commented Feb 6 at 8:42

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