Framework tablet build for Embedded development

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 :rofl:. 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.

https://www.aliexpress.com/item/1005006534723527.html

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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? :wink:

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.

https://a.aliexpress.com/_EQFWOE5

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