Hi I’d very much like a framework tablet that could use a wacom stylus. My original idea was to 3d print a framework “backpack” for a samsung s9 tablet (same thickness as the touchscreen used for the original framework tablet). The only thing is you’d have to use 3rd party software to be able to use android with the framework and the one I know of is designed for windows. There is also the asus pro art, which is also windows only. If you guys can figure out how to get an old surface pro screen to work that would be way better.
I tried to post on the surfaceLinux reddit, if there is somebody with the knowledge of the i2c and spi protocols that the screen uses, so maybe I will get some info there. Support for it was developed for the as part of the surface kernel, so hopefully I will get some info.
If I know the protocol, but I can not get it to work in windows with the drivers, there is always the option to use a microcontroller like an stm32 process the data from i2c/spi and just push it to the device as hid through the usb.
The i2c could just be HID over I2C, in that case there is an FTDI chip exactly for that, but that still leaves the spi on the table. SPI is supposidely used for the pen data.
I will probably have to make my own adapter from framework edp to the surface edp, since the connector they used is pretty exotic in combination with edp, at least on aliexpress, so this might get costly, however I am thinking about a simble flex pcb with both connectors and then I will just hopefully make it work somehow 
and for the touch either ftdi or the stm32, we will see.
Small status update, I decided to try and lay out a small adapter pcb, I have only the edp signaling ready. I’ve tried to stick to NXP displayport layout guidelines so all traces for diff pairs are length matched, the guide says to keep it withing 5 mil, I managed to route them to within 1 mil of length. However, signal quality will be questionable at best, lets just say that the pcb looks like abstract art, since the pairs are crossing on the pinouts. I have to figure out the rest of the connections, mainly for the backlight. But I will check the other adapters here on the forum and hopefully figure out the rest.
One questionmark is the i2c interface comming from the LCD, it is definitely not touch, hopefully it can be left disconnected, otherwise there would have to be some more logic to handle that.
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You may find that the I2C interface is what communicates the LCD details (resolution, size, etc) to the video hardware. This was a scheme introduced in VGA displays a long time ago, and I suspect it continues on to current production displays.
Yeah, I am worried about exactly that. With MIPI, it sometimes is not needed, but not sure about eDP.
I am starting to look at other options for LCDs too. Lenovo screens are good candidates, since they have pen support.
The MIIX replacement LCDs are really nice, although they run about $150. There is also the ElitePad 1000 G2 which is 10 inch but has 30 pin edp + i2c for touch and pen.
One more thing: video about hacking the wacom digitizer https://youtu.be/Zsaeg7UrHr4?si=KFLD7hjgeFHo99rB
It would be lovely if there was touch lcd compatible with the digitizers, since the protocols seem relatively documented and are available cheaply on ebay.
Finally schematic dump on the ElitePad LCD since there are schematics on iFixit website
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This is true for VGA/DVI/HDMI, but it is false for DisplayPort and eDP panels specifically. With those, the AUX channel is used for all such communications instead. The I2C interface on that LCD is more likely to be for features like eSOL (instant on logo, apparently?) or DDS (no idea what that is but shows up in TL070FVXS01 datasheet). Of course, there might still be a DDC interface on that I2C, but it’s not a guarantee by any means.
What I’d recommend is connecting the panel I2C, but through jumpers you can cut, or maybe add two resistor footprints that you can populate later.
It seems like the project might be on hold until I find some other framework motherboard for sale in EU, since the seller stopped responding 
If the surface pro screen is not doable, I am starting to lean towards a frankenstein solution like this one: https://www.youtube.com/watch?v=euFDoqKdiqo I will have to do lcd panel surgery but good thing is the chinese also sell separate panels 
. Of course this should be compatible with the 10.2 inch ipad screen too, provided that the backing can be removed.
I did more digging in the surface schematics, it seems like the VCC_EDP_BKLT_OUT coresponds to the backlight power on the framework, the BKLT_FBx is some feedback for the driver, not sure how needed that is. So L_BKLT_CTRL_IN and L_BKLT_CTRL_OUT + PANEL_WPM are left for reverse engineering.
Is there some documentation around the framework edp interface? It might come in handy at this point.
Are you looking for documentation beyond the basic pinout?
Also, are you married to the 12" size? I just wonder if the slightly larger screens from Dell laptops with Wacom digitisers might make your whole project easier… OLED too.
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Any additional documentation would be great.
I might have to reconsider my desired form factor, that Oled screen is pretty nice + it has wacom pen, which makes it quite a bit easier. I suppose the eDP would also be directly compatible.
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I’ve made a conversion PCB for the SP4 screen, still first iteration and missing few things, but backlight circuit is hopefully implemented and most of the connector routing is also done.
The PCB should be manufaturable as a standard 4 layer PCB under 50x50mm, so they will do 5 PCBs for $2, question is if the tolerances will be ok, or if it will need the tighter tolerance vias, which would bump the price to about $40-50. Partial assembly would be in the ballpark of $50 for 5 pcbs.
However, I am not 100% sure this will work.
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I managed to get my hands on a perfectly functional screen from dell 7280 for about 37€ from ebay. From what I’ve checked (after ordering, of course) it does not support touch, however big plus is that the digitizer communicates through usb 2.
Now here comes the fun part, I will have to get my hands on the framework edp cable here in Czechia, sadly framework does not officially do business here, so I would have to have it shipped to Austria and go for a roadtrip.
I guess I can try to ask Framework if they have some scratch and dent edp cables they could throw away in my general direction and I could cover the shipping? 
But I will most likely have to go for a roadtrip.
Regarding the surface screen I am not giving up yet. I will be ordering parts for an unrelated project on mouser, so I will probably grab all the connectors, etc… for a couple of adapter boards and order the pcbs from jlc afterwards.
Another good display option might be HP 1012 g1 or 1013 g3 screens and Dell 7200, they should all support styluses and they are relatively plentiful on ebay.
Edit: I got my mainboard on friday and already prepped it with ram, ssd and windows. Everything seems to be working well with an external monitor and charger.
Bad idea how to get usb and i2c lines from fw edp connector…
It would probably also work well for the surface screen, but I have no idea how well these work, signal integrity probably won’t be great.
They are super cheap on aliexpress, so that´s a plus.
It’s not that bad
Probably not but it might be good enough
so the main cost would be it being tedious XD
I am worried about the signal integrity, if I were to cut the cables and solder them to some 30 pin edp adapter. But it might work with the 30 pin dupont.
I checked the tolerances for edp differential pairs and the spec says it is 5 mil of trace length, so not much, but it will probably still work.
We will see.
Good news/bad news. They sent me the wrong display. Good news it has pen support, bad news it is from dell 5289 and it came without the control board, so I will need to figure out how to get the control board, hopefully they can send me one for this display and then i will have to figure out how to hook it up. It is a wacom board that uses the combination of usb and i2c interface and has a 10 pin connector.
I found the board on aliexpress and there seems to be test points for i2c and DP/DN (probably the usb). Tehcnically if I figure out the voltages, I can use the test points to interface with the board.
So next steps will be figure out the eDP and get the touch working. I will also start working on some sort of a case in cad.
I will post an update once there is some progress
That’s not needed. Framework has allowed freight forwarding within the EU recently:
Short progress update, I got the screen, touch board and an usb-c to edp + usb adapter. I managed to connect it all up and I am working on getting the touch and pen working, currently I started by bringing out the usb signals from the touch board into the usb-c screen controller. Here is a behind the screnes work in progress photo. I think the connector on the board is for 10 pin 0.4mm ipex connector, so next steps will be to design an adapter board, to connect this to framework properly, after I get it to work.
The screen itself is working and I can get a good image with no glitches, however there is some visible burn in or maps on the screen, so I will have to hunt for a different one in better condition for the final build.
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