Mainboard eDP -> 7" Display

I’m working on a Mainboard project which involves using a smaller screen than the stock BOE display. I wanted to see if I could use the Mainboard’s eDP connector, so ended up choosing this 7 inch display for the LattePanda Sigma, as that board’s eDP pinout matches the output from the stock Framework eDP cable.

After getting the {7" display + its cable} and the {mainboard + its cable} in my hands, I realized that in order to make everything to play nicely together, the configuration would have to be like this:

Framework Mainboard → Framework eDP cable → first I-PEX 20455-040E → second I-PEX 20455-040E → LattePanda eDP cable → LattePanda display

Chaining together the first and second I-PEX connectors requires a PCB, so I made one with M2 holes on EasyEDA that can be ordered via JLCPCB: I-PEX 20455-040E Interconnect - EasyEDA open source hardware lab

I spent zero time on parasitics and haven’t received/tested it yet, so caveat emptor until I post an update. In any case, I hope this is useful for people working on similar problems, especially @MJ1 and @scope who were trying to get a different LattePanda screen to work in this thread.

(I previously posted about this in a different thread, but wanted to break it out into a cohesive whole here)

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Really curious if the touch functionality fully works for you as it should!
This sounds really amazing.

Update: boards arrived, they work flawlessly! I encourage using this setup if you’re looking for a smaller screen for your build and want an extra USB-C port. Only thing I’ll mention is that the touchscreen on the 7" display is I2C so won’t work out of the box, only the pixels themselves.

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Good to know about that screen working. Even if the connection chain does look unwieldy to use.

There are various other 7" and 8" displays on AliExpress but most of their controller boards are HDMI only. They’ll need their own adapter PCB. I found such an adapter here, and curious to see if this eDP to HDMI adapter would play well with the Framework.

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Check this thread for more controller boards:

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Hey quick question- do you still have brightness control? Is the wake from sleep behaviour as expected? Looking at implementing this in my next framework handheld.

I unfortunately haven’t gotten the chance to test brightness control or wake from sleep. I should get to that phase of my current project in the next couple of weeks though and I will certainly update the thread!

I’ve purchased the screen and ordered the adapter from jlc pcb. whenever those arrive i’ll update this thread too.
I’ve also been in talks with the folks at latte panda and since this display’s digitizer uses a goodix gt911, any i2c to usb adapter that works for the goodix gt911 should work with this unit. There are also libraries to use the arduino as an i2c converter for this digitizer specifically, so if the generic i2c to usb adapter doesn’t work, thats also an option.