Nexus 7 LCDs

[BobRocket]

I have a couple of Nexus 7 screens with broken digitizers, the LCDs work fine (just the screens, the N7s have been repaired with new screen assemblies).
Has anybody any ideas on if it is possible to hook up these screens to use in display only mode with the raspi, otherwise they will just end up in landfill (which I would like to avoid if feasible).

[klricks]

I have a couple of Nexus 7 screens with broken digitizers, the LCDs work fine (just the screens, the N7s have been repaired with new screen assemblies).
Has anybody any ideas on if it is possible to hook up these screens to use in display only mode with the raspi, otherwise they will just end up in landfill (which I would like to avoid if feasible).

Not a way to do a direct connection.
You may however be able to remote connect (SSH, RDP etc) to the RPi over WIFI connection on your local network.

[aBUGSworstnightmare]

Is there a model number on the displays and/or do you have the spec?

Most likely they have MIPI interface (DSI) -->not possible to connect to RPi atm.

[saper_2]

Hi,

You got my attention because I'm owner of Nexus 7 too. I looked quickly through internet. there is 2 models of Nexus 7.
- 1st model the older a.k.a. 2012 - this one is equipped in lcd part number 070WP03S - 1280x800px . Nexus 7 2012 have Nvidia Tegra 3 CPU and according to Nvidia tech spec, Tegra3 have MIPI-DSI interface...
- 2nd model the newer a.k.a. 2013 - this one have Snapdragon CPU so it's my guess it's have too MIPI-DSI - S4Pro is from bcm as so Pi SoC, so it'll have DSI too...

Overall, nice thought, but it's impossible (well nothing is really impossible...) to do it:
1. you need a datasheet for screen - probably you won't get that ever in your life...
2. you need whatever it is (source codes of Pi GPU, etc...) for adding support for this display to RPi - you'd need to have really good friends in RPi Foundation and/or in bcm...
3. You have to build interface board - this is pretty difficult taking into consideration what high frequency signals that board have to carry, nevertheless this would be the most easy thing to do

To sum it, you'd waste a lot of time, money and you'd get nothing...
I'm feel bad for braking your dream

[aBUGSworstnightmare]

If it is this display http://www.panelook.com/CLAA070WP03_CPT ... 15772.html then the spec is i.e. here (in case you have no panellook account) http://www.dragonwake.com/download/exyn ... WP03XG.pdf (but I don't know if this is the same rev/version as the screen in the NEXUS).

Based on this data the display has a 6-bit LVDS interface, data mapping info is not given so would have to be tested.

Conclusion: with the right LVDS adapter board and a suitable cable adapter it should be possible to use this display with RPi. Developing an LVDS adapter is no 'rocket science': viewtopic.php?f=45&t=157109

[aBUGSworstnightmare]

Ordered a replacement Nexus 7 display ... let's see how far I can get ...

[saper_2]

Hi,

You ordered display for N7 2012 (a.k.a. Gen1)

I'm owner of N7 2013 (aka gen2 ), I took it apart (not so much ) and snapped some photos. I couldn't find any clues about display (no exact model - only asus P/N as if that would be helpful... ) nor interface. I've uploaded them on gdrive: https://drive.google.com/folderview?id= ... sp=sharing maybe you might have more luck .

As for interface, true: there is no need for complex adapter board, at first I thought that this wide dual-connector FFC is a LCD interface .

As for bit order I noticed in linked by you DS there are 2 signals in connector: LVBIT for changing 6/8bit per color and other one is LVFMT for bit swapping order. There is note "GND" at those signals but I don't know what to think about it...

As for N7 2013 lcd, it have 31pin connector too, and the beginning of signals might have very likely that same layout as lcd for N7-2012, only last 6 signals are the question, 3 of them will be backlight power for sure (there are 2 thick tracks on FPC cable)...

[aBUGSworstnightmare]

Received my replacement digitizer/display unit - it's a CLAA070WP03 XG. The connector is a 0.3mm 31pin FFC.
I will design a small adapter PCB either for use with the original Nexus LVDS cable or go for a 31pin FFC to 2.xxmm adapter. The rest looks trivial to me when looking at the modules data sheet. Too bad that the digitizer will be just a cover lens later since its not possible to get this working without having details on it.

[bensimmo]

tagging into this post .. as a person with such a screen (version1).

Would there be anything useful to get out of android to see what you could do with the touchscreen ?

(I would need to find where I put the nexus 7 first though, it could honestly be anywhere though Not used it for quite some time. Yes completely routed and whatnot.)

[saper_2]

aBUGSworstnightmare (btw. good nick ) I suspected it to be 0.3mm pitch but the connector have 2 rows of solderable pcb pins at 0.6mm spacing (I have some similar connectors for eink display).

It would be cool, but I couldn't find any datasheets for touch controller(s).
The touch controllers are:
- for N7 2012: ELAN eKTH10368WS
- for N7 2013: ELAN eKTH325BAWS (or similar),
But ELAN don't have any info about them on www. Driver code for linux for those ELANs is available so there shouldn't be much trouble to port them to Pi kernel (or even just enable... - I didn't check it - this is just assumption...). I know they works on I2C - just checked on my N7 2013:

Code: Select all

root@deb:/sys/devices/i2c-3/3-0010 # cat name
elan-ktf3k

If we had at least pinout of those controllers then it might be possible to find some replacement chip from Microchip, TI, Maxim, Atmel or others...
Well, at lest we nice and wide mounting frame (and screen protection too )

----- edit -----
The displays have FFC connector so we need also FPC. Generic "straight" cable cost as much as display itself (bare display without touch panel, on aliexpress: ~$14). 3-4 times cheaper are "original" FPC cables with FPC contacts and Board-to-Board connector. I tried to identify the board-to-board connector (Mezzanine connector) part number. I measured both: socket (receptacle - I'll call it `socket` ) on PCB and plug on FPC cable:
- PCB socket: 9.3 x 2.09 mm and height: 0.8mm - so I have to look at connectors with 0.8mm mating height.
- FFC plug: 8.6 x 1.4 mm and height: around 0.65mm
Pin pitch: 0.4mm (I'm certain. I've added to my photos few more with STM32F103 in LQFP-48 (e=0.5mm) & FFC 39x0.3mm connector - this one have 2 rows solder-able pins at 0.6mm pitch per side - at photos visible one side )
I've poked around Hirose and Molex for BtB connectors matching those dimensions and I found (from the most fitting):
- Molex - pcb socket: 503772-3410 , FFC plug: 503776-3410 (I think, it will be those)
- Hirose: BM20B series 0.8mm height
- Hirose: BM14 series 0.8mm height

[BobRocket]

Hi all,

the two N7 displays I have are HYDIS ones from the first generation, cheers for the data sheet and info.
Whilst I was clearing out I came across another 2 cheapo tablets, one I managed to resurrect by resoldering the power connector the other has a cracked digitiser (a common feature), the display is an AT07QTN93 so that one should work quite easily, the digitiser is not welded to the display like the nexus's so it might make a good smart mirror display.

I did find a data sheet for the Elan eKT8150 Capacitive Touch Pad Controller which might be of some use, I've put a copy here

http://www.democraticbritain.org

[saper_2]

Whilst I was clearing out I came across another 2 cheapo tablets, one I managed to resurrect by resoldering the power connector the other has a cracked digitiser (a common feature), the display is an AT07QTN93 so that one should work quite easily, the digitiser is not welded to the display like the nexus's so it might make a good smart mirror display.

Sorry, google do not know "AT07QTN93" - is this correct? I'll look if you give a valid symbol , abugsworstnightmare probably will look too - If those have LVDS then they will work (i'm not sure but I might saw similar symbol. I think it was with some Chinese hdmi->lvds converter board...)
Please, do not mix into this topic other displays - this topic is for Nexus 7 lcds

I did find a data sheet for the Elan eKT8150 Capacitive Touch Pad Controller which might be of some use, I've put a copy here

http://www.democraticbritain.org

Link down: HTTP Error 403 - Forbidden

Also, I've edited my post above with some tech info about connectors & updated photos on gdrive with better look on connectors.

[BobRocket]

try this for the 8150 datasheet
http://www.datasheetarchive.com/dl/5a36 ... an+eKT8150

sorry, meant AT070TN93 similar to Tontec screen and would probably work with the control board by aBUGSworstnightmare

[BobRocket]

don't know if this helps, 1st gen ME370T board layout with touch connector on p29, con5 on p23 looks like it might be the LCD connector.

https://www.google.com/url?sa=t&rct=j&q ... ATWHLW4WcA

[aBUGSworstnightmare]

try this for the 8150 datasheet
http://www.datasheetarchive.com/dl/5a36 ... an+eKT8150

sorry, meant AT070TN93 similar to Tontec screen and would probably work with the control board by aBUGSworstnightmare

AT070TN93 is a 800x480pixel module from Innolux with 24-bit RGB interface --> can be connected to the RPi GPIO directly with a suitable adapter PCB (50pin FFC to 2.54pin pinheader). This is what I'm doing here i.e. viewtopic.php?f=41&t=154571 - no 'glue logic' required. But you will have to design a custom board for this screen!

[aBUGSworstnightmare]

don't know if this helps, 1st gen ME370T board layout with touch connector on p29, con5 on p23 looks like it might be the LCD connector.

https://www.google.com/url?sa=t&rct=j&q ... ATWHLW4WcA

Well done - http://www.digikey.de/product-detail/de ... ND/1987297 - schematic names Panasonic connector

[saper_2]

don't know if this helps, 1st gen ME370T board layout with touch connector on p29, con5 on p23 looks like it might be the LCD connector.

https://www.google.com/url?sa=t&rct=j&q ... ATWHLW4WcA

Well done - http://www.digikey.de/product-detail/de ... ND/1987297 - schematic names Panasonic connector

A one hell good finding - the service manual.
I didn't know that Panasonic manufacture a BtB connectors... Link to digikey don't work, The connector is F4S : AXT5.... AXT6xxxx is "the plug" (Panasonic name it header).

AS for N7 2013 - this not help much, I checked other Panasonics connectors but none fit what I measured... Anyway I've ordered one LCD fpc for N7 2012 and 2013 , also I ordered 5pcs (for 3,22USD with cheapest shipping) the AXT530124 from aliexpress too, so around December they should arrive . Then I'll think later what to do

[BobRocket]

ME571K layout in 2 parts.

ME571K LHS

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There is a repair manual out there somewhere but I haven't found it yet

[BobRocket]

ME571K rhs

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[aBUGSworstnightmare]

Just for information: Started designing an adapter PCB for the Nexus 7.

Connection is as below:

LCD --> orginal FPC --> adapter PCB (ATX530124) --> Hirose DF14 series connector (to host)

Why did I choose a DF14 series connector? Simply due to the fact that quite affordable interface cables are available for this type of connector (http://www.banggood.com/20Pin-DF14-20-2 ... 77748.html) which I can use with my LVDS add-on board.

[aBUGSworstnightmare]

Released the PCB order today.

PCB top side, showing dimensions as well

top.png (5.78 KiB) Viewed 55775 times

Will operate the BL at 4.2V - similar to tablet.

'Paper sample' for giving a dimension idea. Connector matching the original FPC is on bottom side of PCB. LVDS is now available on DF14-20 connector

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[aBUGSworstnightmare]

... postman had some nice 'bling bling' in his car today: received the PCBs! 12 days turnaround time (order to delivery) from China to Germany is not bad...

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Well ... this socket connector is REALLY small.

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Will assemble some PCB's tomorrow and then start testing. Hopefully they will work ... so keep fingers crossed.

[saper_2]

Hi,

Nice PCBs, how much did you you paid for them? They are tinned or gold-plated (can't tell form photos)?
And, yes I have my finger crossed and hold thumbs too

From this point everything is my assumption and observation only - those are not facts proven by datasheet(s)

You have some experience with LVDS, did you know something about 6 pair of data/clock to lcd panel?
I usually found 5 or 8/10 pairs...
I found on this page that there might be 6-pair I/F: https://sites.google.com/site/lcd4hobby ... -pin-cable (on one screenshot from datasheet page).

I found on N7 2013 lcd ribbon for certain 6 routed pairs:
- equal spacing between tracks in pair & GND planes,
- both tracks of each pair seems to have equal length,
- each track of pair have as neighbor the another track from pair,
- the pair neighbor pins in CON1 are GND too...

That's, leave 4 more tracks - they're not routed in equal spacing nor to neighbor pins in CON1 (PCB BtoB connector).
I suspect that, those left 4 wires are:
1. BL_EN
2. BL_DIM (PWM??)
3. ?
4. ?
Might be DDC on 2 left (SDA & SCL) but I don't have an idea how to check this without soldering....

I have added to my google-drive-share a FPC directory with few more zoomed photos of FPC ribbons and calc (excel) file with connections on FPC from LCD to PCB connector. (Link: https://drive.google.com/drive/folders/ ... jNtbnhkcTA )

[aBUGSworstnightmare]

Hi,

Nice PCBs, how much did you you paid for them? They are tinned or gold-plated (can't tell form photos)?
And, yes I have my finger crossed and hold thumbs too

From this point everything is my assumption and observation only - those are not facts proven by datasheet(s)

You have some experience with LVDS, did you know something about 6 pair of data/clock to lcd panel?
I usually found 5 or 8/10 pairs...
I found on this page that there might be 6-pair I/F: https://sites.google.com/site/lcd4hobby ... -pin-cable (on one screenshot from datasheet page).

You need to distinguish between single pixel and double pixel LVDS interface (some refer to them as single - or double channel) and colour depth (6- or 8-bit).

LVDS data mapping A for single pixel display with 8-bit colour

R1R0mapping.jpg (48.91 KiB) Viewed 55558 times

LVDS data mapping B for single pixel display with 8-bit colour. In case of 6-bit colour only Y3 is not available/connected

R3R2mapping.jpg (49.59 KiB) Viewed 55558 times

6-bit single channel LVDS. Compare to 8-bit.

6bit.JPG (44.69 KiB) Viewed 55514 times

Let's take the Nexus 7 as an example. Colour depth on the Gen1 display (the one that I have on hands) is 6-bit, that's why it has 3 differential signal pairs for data Y0 to Y2 (Y0 is the upper channel in the mapping charts and Y3 is the lower one).
Single- or dual pixel is (let's say most of the time, there are exceptions to this as well) related with the displays resolution: single pixel (channel) LVDS is possible up to HD (1366x768) pixel.
In addition to this it needs you need to have a differential signal pair for the clock signal.

Hi,

Nice PCBs, how much did you you paid for them? They are tinned or gold-plated (can't tell form photos)?
And, yes I have my finger crossed and hold thumbs too

Total price for the PCB is roughly USD40 with transportation cost being higher than actual PCB cost (USD12). They are HAL only: no need to spend anther USD26 for ENIG (since I'm just using them as proof-of-concept samples).

I found on N7 2013 lcd ribbon for certain 6 routed pairs:
- equal spacing between tracks in pair & GND planes,
- both tracks of each pair seems to have equal length,
- each track of pair have as neighbor the another track from pair,
- the pair neighbor pins in CON1 are GND too...

That's, leave 4 more tracks - they're not routed in equal spacing nor to neighbor pins in CON1 (PCB BtoB connector).
I suspect that, those left 4 wires are:
1. BL_EN
2. BL_DIM (PWM??)
3. ?
4. ?
Might be DDC on 2 left (SDA & SCL) but I don't have an idea how to check this without soldering....

I have added to my google-drive-share a FPC directory with few more zoomed photos of FPC ribbons and calc (excel) file with connections on FPC from LCD to PCB connector. (Link: https://drive.google.com/drive/folders/ ... jNtbnhkcTA )

To me this looks like 8 differential signal pairs! The display is FHD resolution so it needs to be dual channel LVDS (odd and even channel) --> you will have 3 data channels and one clock channel for odd and even LVDS channel. This results in 8 differential signal pairs, but colour depth is 6bit only for this connection. Will be hard to tell what goes to where without having the displays data sheet...

By the way: the Nexus 7 Gen1 is 6-bit colour as well.

[aBUGSworstnightmare]

... build 1st sample ..

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