Hello,
I have a Pmod VGA (Pmod VGA - Digilent Reference) and I want to try connecting to the Due. I have read the DueVGA library of @stimmer and I'm at a loss for the fixed nature of the pins.
First of all, is this doable for the converting like this? I'm aware that the hardware may not be the best for this experiment, but I still want to try.
If this is possible, is there any advice for adjusting to the 12-bit RGB of the Pmod, as well as adjusting the pin's location?
Thank you in advance.
Firstly, the DueVGA library uses the DMA controller to write data to external memory. Now we do not actually have external memory, we are just using the Data lines of the bus, the address lines are not used. Effectively it is creating a fast 8 bit IO port that the DMA controller can write to.
On the Due the external memory interface is on fixed pins, namely PC2 to PC9, it is not possible to remap those to other pins.
So the next question is can DueVGA be adapted to use 12 bit color? I have not checked, but I assume that the DMA can do 16 bit transfers, and use D0-D11 on the external memory interface to output 12 bit color. However, the DueVGA library has a lot of low level code and optimisation assumptions for 8 bit data, so it would probably require extensive and tricky rework to make it work for 12 bit color.
It would be a fun project, and get you into the gritty details of the SAM3X. Probably not something I would bother with in software, I would look for other hardware solutions.
Thank you very much for explaining the basic. Seems like I'm not hoping for a favorable result.
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