Electronics > Projects, Designs, and Technical Stuff
Connecting a 4 channels LVDS LCD (without EDID) to a 3 channels motherboard
PaddleStroke:
Hey guys!
I started a video project of upgrading a laptop screen which includes heavy modding. Though I stumble on issues for connecting the LVDS interfaces :
My plan is to fit a 20" 1600x1200 4:3 LCD (LM201U05-SLA1) from a Dell Ultrasharp monitor (2007fPB) inside my 17" 1600x900 Asus (N71JQ) laptop (LP173WD1). From the 17" datasheet I found what I was expecting : 3 LVDS channel + 3.3V power + EDID + backlight power.
For the 20" it's troublesome :
- First it's a 4 channel LVDS : Can I just leave the 4th channel floating or grounded and only connect the 3 other channels?
- Also the 20" does not have EDID storing LCD timing/resolution settings. I am unsure how to proceed. I was considering keeping the 17" controller board with only the wires for the EDID (while the other LVDS wires would go to the 20" controller board), and overwrite the EDID set to the new LCD timing controls. Though the issue is that I have not clue how to write the EDID (both how to flash it and how to write it's code).
Anyone one with some clues is most welcome !
Thanks!
c64:
--- Quote from: PaddleStroke on July 31, 2020, 05:25:21 am ---- First it's a 4 channel LVDS : Can I just leave the 4th channel floating or grounded and only connect the 3 other channels?
--- End quote ---
Usually 4th channel is the MSB for all colors. What is in the datasheet for the screen?
PaddleStroke:
It seems to me from the LM201U05-SLA1 datasheet (which I can't attach here but is easily found online) that you are correct. The 1st and 2nd (R0 R1 G0 G1 B0 B1) bits are the less significant indeed. Would that mean that the channel 0 is to be left unconnected instead of the channel 3?
Though I am unsure if the 0 and 1 bits are the ones carried by the channel 0.
PaddleStroke:
I have been having a closer look at the datasheets. In the 17" datasheet I found that
--- Code: ---Odd_Rin0- - LVDS differential data input (R0-R5,G0)
Odd_Rin1- - LVDS differential data input (G1-G5,B0-B1)
Odd_Rin2- - LVDS differential data input (B2-B5,HS,VS,DE)
--- End code ---
So it seems that channel 0 is carrying R0 to R5 + G0 and so on.
Looking at that it feels really really difficult to match the LVDS interfaces...
c64:
Looks like your only option is to de-serialize lvds -> rgb, convert 6 bit color into 8 bit, when serialize it into lvds
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