Monochrome VGA driver?
Rayman
Posts: 16,458
Guess this doesn't exist yet...
Thinking this could be useful for the case of RJ45 cable with only 4-P2 pins available.
Thinking pins like this: HSync, VSync, Video, Audio
1080p with mono video and audio isn't great, but probably best can do with only 4 pins...
Comments
Changed title to grayscale to a sec but 1080p would still need external ram. Monochrome looks to be <300kB…
If you need to adapter it to a standard connector at some point anyways, you could put a sync stripper/seperator in there and send Sync-on-Green down the wires instead.
(LMH1980 seems like the part for that)
My driver should do single colour monochrome it if you setup LUT1 colour mode and only wire up to one channel but it wasn't really optimized for this type of output "mode". If you want to use it for text you may need to use this FORCE_MONO_TEXT option IIRC. But for graphics you can use LUT 1bpp, and right now all 3 RGB colour pins get allocated which is probably not what you want if you are doing it to save pins as well as memory. It supports 5, 4 and 3 pin VGA via RGBHV, RGBS and RGsB (sync-on-green) outputs. A 1-pin VGA with SoG would be handy at some point if monitors support it. I had an older paper-white monochrome VGA monitor which might have been good for testing that but it blew up years ago unfortunately. That was a nice little monitor.
Thinking might be able to do yellow on dark blue with some resistors on the load end…. Think better than black and white …
Some time ago I wrote a 1080p VGA driver for an EC32,, 8 bpp with palette registers. It can be reduced to monochrome by disabling 2 color pins (R and B, as standard VGA mono signal goes on the green pin) and then bypass palette registers as they are not needed for monochrome.
1080p needs a lot of bandwidth. To make things easier for the P2 and PSRAMs I used 50 Hz refresh rate. This reduces the pixel clock from over 150 Mhz to less than 130 MHz. Lower pixel clock gives more time to write pixel data to the PSRAM.
Think see a 1 bit lut streamer mode so maybe could be easy to do…
But would just have black and white in lut and use only 1 pin for color.
On other hand could also be useful with all the color pins if want hires text in 1080p without external ram…. Each character could have own colors…