Guru
Joined: 05/10/2019
Location: United KingdomPosts: 7020
| Posted: 02:02pm 04 Nov 2024 |
Do you want a design to test it with? I may be able to do that, but it will be very limited in other respects if the board size is to be kept to a reasonable size. The current design would have to lose the rear USB sockets in order to get the VGA connector in. There is no space to move them to the front unless I force a micro SD card.
I don't want to exceed 100mm x 100mm PCB size if possible as the cost from JLCPCB goes up.
The individual wiring within the HDMI leads is almost exactly identical. It's not the overall length that's the problem, it's the phase difference between the four channels that matters. The data lines have to stay in phase with the clock and the data is on both the leading and falling edges of that. And it's a fast clock. You don't have a lot of leeway on the PCB really. We are only getting away with it at the moment because we aren't using the full capabilities of HDMI.
I suspect your circuit may need some careful layout to prevent the VGA traces from interfering with the HDMI. At the very least they will introduce additional capacitance to GND, degrading the data edges. That doesn't mean that it's not possible, but it may mean that it doesn't work on a first attempt. :) It may even work fine with the wiring hanging in mid-air but not when you put it on a PCB.
VGA RGB222 isn't currently possible in MMBasic, by the way. Only RGB121 is supported.
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Edited 2024-11-05 00:06 by Mixtel90