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hoglet67 / RGBtoHDMI

Bare-metal Raspberry Pi project that provides pixel-perfect sampling of Retro Computer RGB/YUV video and conversion to HDMI
GNU General Public License v3.0
808 stars 112 forks source link

Analog Board on C64 #244

Open lolof70 opened 2 years ago

lolof70 commented 2 years ago

Hello,

I soldered an analog issue 3 board for my C64 (with FPGA video mod). It does not work well, missing colours or something like that. Seems there is no red or blue.... I built the board following the BOM made by Kicad. Trying to get the board working, I saw a bom on the wiki right now... There are not both the same (both boms).... On my board :

On the wiki :

.....

Can it be that I have a problem because one or more of those are not correct on my analog board ? Or it should also work correctly with the parts I soldered ?

Here pictures from the RB2HDMI in action.

Thank you very much for help and advice.

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lolof70 commented 2 years ago

Just put R1 with 470 Ohm. It does not help.... :-(

Also tried the fix from there

https://github.com/hoglet67/RGBtoHDMI/issues/236#issuecomment-913149715

Does not help unfortunately.

Just in case, here is how my cable is done.

1635931437234

And here some more info... I did it with the bridges made on U3, they are still there... Done with fresh SD card installation, I just choose the C64 profile at first boot from the Pi.

Thank you for helping me.

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lolof70 commented 2 years ago

Oh yea.....

Problem solved. When I built my fpga video board for the C64, I replaced 2 resistor with lower value one to reduce the colours saturation.... I put the original value back and all is working. Perfect !

I also tested with the bridges on U3 removed. Still work perfectly.

Thank you for this very nice adaptor.

IanSB commented 2 years ago

@lolof70 Sorry, I only just noticed your post, glad you got it sorted out already.

As you discovered, the RGB values have to be at predictable levels which are set either by reprogramming the colour tables (with older c0pperdragon firmware) or by putting the fpga board into the special RGBtoHDMI mode (with newer c0pperdragon firmware).

The analog board level slices the RGB values to extract the bit-exact digital data from the C64 and by changing the resistors you messed up the digital extraction.

I built the board following the BOM made by Kicad. Trying to get the board working, I saw a bom on the wiki right now... There are not both the same (both boms)....

The wiki is correct, the values got changed (to improve performance or because components were not readily available) without requiring a PCB update so the kicad files didn't get updated

lolof70 commented 2 years ago

Thank you very much for the reply. I must say, it's working very good with the bom from Kicad and R1 with 470 Ohm. It's just perfect, at least with my C64.. Thanks for all.