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FPGA VGA Controller for 8-bit computer

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BrianHG:
Take the 14bit parallel output.  Add 2'b00 as the bottom 2 bits and you got a 16bit parallel output.

You can also use the 3 separate output and place channel 1 on left added to channel 2, and channel 3 on right added to channel 2, making 2 a mono center channel.

Or, make 2 synths, one on left, one on right.

Make 3 control ports.  control port A would drive both synths in parallel meaning a fallback mono audio.  Control port B and C do the same as A, but B exclusively drives the left synth and C exclusively drives the right synth for stereo sound.  Or, do whatever you like.  Add 4 synths, 1 left, 1 center, 1 right, 1 rear offering 12 audio channels.

BrianHG:

--- Quote from: nockieboy on July 05, 2022, 09:46:40 pm ---Oh, one last thing - putting the output into HDMI mode seems to cause the layering to fail.  In DVI mode, the display is 720x480, but with a layer 40 pixels thinner and shorter than the display resolution, centred on the screen to show a 20-pixel wide border around the edge.  When I switch to HDMI mode, it's as if the layer becomes 720 pixels wide and the border disappears except for a thin strip and the top and bottom.

Any ideas?

--- End quote ---
When in HDMI mode, some monitors may be applying an overscan-scale.  Look for a 1:1 pixel setting on the monitor, or, maybe there is an automatic border set by the HDMI transmitter IC as we are basically adding dummy borders around the image to make the 148.5MHz pixel clock appear as a 108MHz clock.  IE: try 720p or mode 0 instead of mode 7 480p and see if the problem persists.  (Because of the fixed pixel clock, mode 0 480p will be at a higher framerate than 60hz.  IE: 66hz instead of 60hz when using pixel divide by 5.)

nockieboy:

--- Quote from: BrianHG on July 05, 2022, 10:27:55 pm ---When in HDMI mode, some monitors may be applying an overscan-scale.  Look for a 1:1 pixel setting on the monitor, or, maybe there is an automatic border set by the HDMI transmitter IC as we are basically adding dummy borders around the image to make the 148.5MHz pixel clock appear as a 108MHz clock.  IE: try 720p or mode 0 instead of mode 7 480p and see if the problem persists.  (Because of the fixed pixel clock, mode 0 480p will be at a higher framerate than 60hz.  IE: 66hz instead of 60hz when using pixel divide by 5.)
--- End quote ---

Can't find a 1:1 pixel setting, but if I switch modes to 1080p, the border is preserved and all is good, so it looks like the monitor is doing some kind of scaling/overscan as you've suggested. Will just have to live with it for the time being in the lower-res modes. :-+

BrianHG:

--- Quote from: nockieboy on July 06, 2022, 08:06:02 am ---
--- Quote from: BrianHG on July 05, 2022, 10:27:55 pm ---When in HDMI mode, some monitors may be applying an overscan-scale.  Look for a 1:1 pixel setting on the monitor, or, maybe there is an automatic border set by the HDMI transmitter IC as we are basically adding dummy borders around the image to make the 148.5MHz pixel clock appear as a 108MHz clock.  IE: try 720p or mode 0 instead of mode 7 480p and see if the problem persists.  (Because of the fixed pixel clock, mode 0 480p will be at a higher framerate than 60hz.  IE: 66hz instead of 60hz when using pixel divide by 5.)
--- End quote ---

Can't find a 1:1 pixel setting, but if I switch modes to 1080p, the border is preserved and all is good, so it looks like the monitor is doing some kind of scaling/overscan as you've suggested. Will just have to live with it for the time being in the lower-res modes. :-+

--- End quote ---
So, the authentic mode 0 480p doesn't work?

BrianHG:
Also, what happened to the speckle dots?
Did you get the line-out to run with the 1khz tone from copying the HDMI I2S output to the audio codec?
Note that since the line out is only stereo, you should only be using data bit 0, but the Mclk, Wclk, Sclk should match and there might be 1 high frequency control clock added to that.

You should be able to re-configure or make your own PLL clock replacement to match the HDMI audio PLL clock rate, but, add a few extra clock outputs for your sound generator module.

The HDMI audio serializer has a parallel data LUT table in it.  You will be taking that table, making sure you separate out the left and right, and make a new parallel 16bit stereo input port with said serializer to send raw parallel digital audio through the HDMI.

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