11-09-2020, 03:19 AM
(07-19-2020, 04:23 PM)oaklarch Wrote: ...
1. There are eDP to LVDS/ eDP to MIPI adapters used for NanoPC T4 and LattePanda Alpha respectively. Both come with their own 7" panels but:
* in case of the T4 the output is a very common 40 pin LVDS able to plug *any* lcd of any size and resolution (as the controller reads the info from the onboard EDID chip). The problem is the eDP in. Out of all the pinouts on their board they used the most obscure 30 pin 4 lane one (afaik only a couple of Macbook Retina panels have it). I'm trying a dumb 2-lane adapter right now, hopefully I'll get some results.
* nothing can be done in case of the LattePanda's one, as not only MIPI is a closed standard but they can even make pinouts differ between the revisions of identical LCD panels. I suspect at this point they make it out of spite. And I seriously wish every member of the MIPI consortium could only use a single toilet bowl on Earth unique to them and none else. On the plus side, the LattePanda one's eDP pinout is the same 30 pin/2 lane.
2. The smallest native eDP panel I know of is a 9" VVX09F035M10/M20 by Panasonic. The funny thing is, its pinout seems also incompatible. How. How did they fudge the most common pinout. How. I've just got mine for inhumane experiments so I'll try figuring out the actual pinout (couldn't find any datasheets on this one).
In case anyone's interested here's the follow-up.
Option 2 failed as it seems Panasonic LCD requires either additional initialization sequence or configuration on the eDP chip's part.
For option 1, T4 lcd also failed (seems like more than a simple pcb converter is needed).
Surprisingly, LattePanda's eDP display works as expected on all my eDP laptops/convertibles I've tried it with. Moreover it's an eDP to LVDS, not eDP to MIPI as I previously thought. The converter in question is PS8625 by Parade Technologies while T4's one uses NXP's PTN3460.
That being said, would it be feasible to make such a converter as a standalone circuit for sale at the Pine Store? Both chips can read EDID info from the LCD so no need to hardwire a specific panel either. And there's quite a lot 7-10" LVDS panels out there either less than 25-30 dollars new or dirt-cheap if salvaged from dead tablets.