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Author Topic: LCD Controller Firmware Issue  (Read 4300 times)
rumbaq
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« on: February 15, 2016, 09:08:31 AM »

Hi guys. As I've already mentioned in the "NJYTouch programmer alternative?" topic, I have some problems with my LCD controller.
It's LM.R25.A4 1291 (declared as an updated RM3251). The default firmware (from the box) didn't work, it even defined my LCD AUO B121EW03 V8 as 1024x768. Then I asked njytouch for another firmware, got the _LTN154X3_L01_SI6L_1280_800_5KEY_IO_ENG_A_R_RM3X51.gff, reflashed but the LCD is still not working properly. Here's the picture of what it shows with the VGA cable plugged.

What could be wrong? Has anybody had the same problem?
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Aerendraca
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« Reply #1 on: February 15, 2016, 11:19:50 AM »

Hmm, this doesn't look great to me. I'll assume that you have a 15.4" 1280x800 16:10 aspect screen since this is what you've asked for the controller to be programmed with. The picture being scrambled like that - in my experience - doesn't appear to be due entirely to a problem with the wrong controller firmware, it looks more to me like a damaged panel; the almost circular splodge in the bottom left corner looks like the panel may have undergone some pressure stress and caused liquid crystal bleed, and the three distinct bands (the colourful scrambled top, the black lines in the middle, and the white(ish) area at the bottom suggest some possible strain which may have pulled some connections on the thin ribbon cables away from the glass.

The area that I suspect is crystal bleed, have you ever seen these pixels change colour? or are they always black?

Can you test this panel on something else? perhaps the laptop it came from (if it came from a laptop).
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rumbaq
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« Reply #2 on: February 15, 2016, 02:58:00 PM »

This 12.1" AUO B121EW03 V8 is 1280x800 which came with the HP tx2000. The laptop was broken a years ago (kind of temperature issue, the LCD worked well), so I saved the LCD and recently I've decided to turn it into a tablet like Trashie did.
Unfortunately, I don't have the other LCD to test the controller... though I'm thinking of getting one to make use of it if I don't make the current panel working properly.
Here's another picture of what happens when there's no VGA cable plugged and I press the menu button a second after power-up. I googled similar clouds before and I thought it doesn't seem like a typical crystal bleed.

And here's one of the pictures I got when tried different color settings and resolution.
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Aerendraca
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« Reply #3 on: February 15, 2016, 09:28:22 PM »

Ok, seeing these pictures I've changed my thoughts on this. I now suspect that your LVDS cable has the wrong pin assignment for your screen. Where did you get the cable? Did it come with the LVDS controller? Did you specify the screen when you ordered it?

Perhaps a photo of the connection between the LVDS controller and screen could be uploaded to the forum? If you can, try to make it so that the connections of the individual wires are as clear as possible from one connector to the other.

In the mean time I will look into the pinout information for your screen (and possibly the LTN154 panel since this is what the controller has been programmed for).



EDIT:

So here's the pinout for the screen (taken from http://www.beyondinfinite.com/lcd/Library/Auo/B121EW03-V8.pdf):

* B121EW03-V8_LVDS_PINOUT.JPG (58.09 KB. 737x487 - viewed 363 times.)


and here's the one for the controller (taken from http://monitor.espec.ws/files/specification_of_r_2_.rm3251c_lcd_controller_board_171.pdf):

* RM3251_LVDS_HEADER_PINOUT.JPG (144.39 KB. 720x844 - viewed 422 times.)


I haven't seriously looked at these yet so I currently have no thoughts on the matter, but I will take a look when I can and see if there's anything that stands out.


EDIT2:

Here's the pinout for th LTN154X3-L01 that your controller has been programmed for (taken from http://www.beyondinfinite.com/lcd/Library/Samsung/LTN154X3-L01.pdf):

* LTN154X3-L01_LVDS_PINOUT.JPG (133.4 KB. 672x832 - viewed 431 times.)

« Last Edit: February 15, 2016, 10:03:30 PM by Aerendraca » Logged
Aerendraca
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« Reply #4 on: February 15, 2016, 10:31:30 PM »

Ok, so i've found some time to look into this. Here's the pinouts compared:


* PINOUTS_COMPARED.JPG (198.29 KB. 1584x589 - viewed 396 times.)



You need to check that the cable you have matches the connections highlighted (colour to colour). Good news is that the ltn154 panel utilizes the same LVDS signals as your 12.1" panel so that's a start. Also, double check that you have the connector at the R.RM3251 end plugged in correctly, with pin one of the black connector (shown by a triangle embossed in the plastic) lined up with the painted white triangle of the pin headers on the LVDS board.


« Last Edit: February 15, 2016, 10:59:39 PM by Aerendraca » Logged
rumbaq
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« Reply #5 on: February 16, 2016, 09:25:52 AM »

Dear Aerendraca, thank you very much.

The LVDS cable was from njytouch and I specified the LCD when ordered controller. I had thought something's wrong with the cables, and then njytouch told it's a software issue (well, it was as well) so I didn't ring out the wires.

When I rang out LVDS cable the wires turned out to be mixed up. The Odd0 on the RM3251 side was connected to ClkIN, Odd1 to RxIn0, Odd2 to RxIn1, OddClk to RxIn2. VddEDID was connected to Gnd so I left it that way.
That's the photo of the LVDS connector as it came. The pins are correct (the wires are not).

This is the LCD with the 1280x800 60Hz settings. As I highlighted, the default H.position of 50 was set to 0, however the picture is not aligned with the LCD borders.

This is the LCD with the 1280x800 75Hz settings. Seems good (yay!).


Lesson to me: never trust the vendor, check all the wires.
Thanks!
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Aerendraca
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« Reply #6 on: February 16, 2016, 01:43:29 PM »

You're very welcome, I'm glad I could help, and I'm pleased you got it working. Nice job!!  Smiley

P.s. I think you should really have the ground wire that's connected to the VddEDID pin connected to pin 16, since this ground wire is to prevent cross talk between the LVDS wires. Grouding the VddEDID pin or leaving it floating is not a problem as you are not using this feature of the panel.
« Last Edit: February 16, 2016, 01:59:47 PM by Aerendraca » Logged
rumbaq
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« Reply #7 on: February 17, 2016, 08:27:52 AM »

this ground wire is to prevent cross talk between the LVDS wires
Okay, I got the point. Sure enough, the LCD's EDID data are not needed since the EDID comes from the RTD2120 as I suppose... Well, I will publish a full build log as soon as I finish the device.
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