So this kinda thing isn’t really PCB design in the classic sense (that is also out of my depth).
All this is really is linking up wires… think of it like splicing two cables together but doing so on a PCB.
Learning to do that is something you should be able to pick up relatively easily. I think I had designed one similar thing before making this adapter. As i note above, when you are screwing with this stuff you have to accept the possibility you will screw something up and end up with a dead mainboard - I got this adapter wrong like 3 times through being a bit dumb and every time I could have linked the wrong pins and burned something out. I don’t want to discourage you, just be clear that you should only tinker with this kinda stuff if you are prepared for the worst.
All that said, you can just get the PCB I have designed above manufactured by JLCPCB on a 0.6mm board (obviously it still have the height of the components) - but it is quite expensive.
If I was trying to fit a cable into an existing laptop chassis I would be tempted to splice together two cables so there was no PCB adapter to worry about. Would need careful soldering and double and triple checking what you are connecting up, but would do away with the potentially cumbersome PCB.
Thanks - the 0.6 mm pcb is an option i’ll consider. I am also looking at getting a small volume of 4-lane 40-pin to 2-lane 30-pin edp adapter made if its not too expensive. I’ve dug in more and basically at this point I have bought an external edp driver to test out future screens so as not to brick my laptop. I am however increasingly confident that other than OLEDs, a lot of screens basically do follow the standard pinouts(will definitely have to verify one by one though prior to using such screen).
There isn’t really a standard for edp pinouts set by anyone, just a set de-facto standards. Vesa specifies how some parts work electrically, the rest is between the display manufacturer and the laptop manufacturers.
For oleds while inconvenient for us it does make some sense to change the pin-out. Since the actual oled panels are very thin compared to lcds it does make sense to offload some of the electronics to the main-board to be able to actually make use of that thinness (otherwise you’d have a thin panel with some not as thin electronics taped to it). Some oleds still have the electronics onboard and use the “standard” pin-outs, others expect you to do some or all the voltage conversion work on the mainboard and have a quite a lot weirder pin-out.
For our application since we are replacing a tick lcd we can just put the conversion electronics between the laptop and the display and either stick it behind the panel or somewhere else but for some panels it’ll need to be done if you don’t want magic smoke to escape somewhere.
Do you think that this would work without modification to convert from the framework motherboard port to the cable on this screen model ?
I get that the site doesnt have pin-out so its not conclusive to say but am I at least understanding correctly that you solved a similar situation (with possibly different type 30pin 2lane eDP screen)
Yes my above solution is similar in that it adapts the Frame work 40pin to a 30pin screen. But without knowing the pinout of the linked screen it’s impossible to be sure.
I can say the 30pin screen I used is fairly ‘standard’, but there are plenty of screens that stray from this standard.
Hmm well might as well try and see not that there seems to be much other options
When I try to place an order through the editor at the project page it seems like the I-PEX 20455-040E-76 is out of stock? Is this Lian Xin Technology 20455-040E-66 equivalent component? It seems to look right in the placement window just swapping it through the part search screen but I havent ordered pcbs before so Im unsure does it need to be changed for the project files too?
“It only needs to be changed at the pick and place stage, as the footprint is compatible.”
Thanks!
“I screwed up the pcb a couple of times and connected the wrong pins and nothing bad happened.”
“I think if you are going with the plug it in and hope approach you do have to be prepared for the worst.”
Yeah I read the whole thread before! I’m keeping in mind that this is very much play with fire and you might get burned type of endeavour.
Nothing bad happened yet but I realised I didn’t account for what the current laptop display cable was like. It seems to be 30 pin I-PEX style cable to 40 pin onboard/pointing up type…
So I would need a ribbon from the screens 30pin to the converter PCBs 30pin (FPC1)
The EDA project also mentions “Standard FPC to I-PEX style eDP 30-pin cables are readily available from the linkes of AliExpress.”
If I’m understanding correctly would it be something like this Aliexpress
But I’m a little bit uncertain about the other end being bare cable like that? Is the lever on the FPC1 actually enough to hold flat cable like that or am I missing the type of end connector I need?
If I do have it correct quite a few of the Aliexpress listings also mention “Forward” “Reverse” as options… which sounds like the cable would be directional? The data is going from the laptop to the screen so in that sense it would make sense for the “forward” to be from the flat end to the I-PEX connector. (That would also make sense since the Framework screen cable from the mainboard goes to the golden connector on the the converter too…) But Im little bit unsure about the direction stuff (wouldnt the pins still align either way since the wires in the cable just go directly from pin to pin)
EDIT: Always find things after posting. So it seems like the Forward and Reverse refers to the sides the traces are on the cable, which matters because the traces can be on the top or bottom on the connectors? Forward is both on same side and Reverse is alternating?
Based on the connector data the FPC1 seems to have bottom pins and the IPEX has top ones… so I would want reversed cable that has top side traces on the screen size and bottom side traces on the ribbon into the adapter boards FPC1?
Yes the ‘open’ cable clamps into the connector just fine. If you are worried about it wiggling loose them tape it down.
If the connectors were laid next to each other the pins would connect up directly across. If that makes sense. So whatever cable you have has to reflect this.
Off the top of my head that should be a ‘straight’ cable. A reversed canble would require you to flip the cable thus reversing the pins.
Iirc the ipex pins are actually on the bottom, even if it doesn’t look that way.
Hope that makes sense!
You can always buy both as they are so cheap and see it practically laid out infront of you.
