search

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
849 stars 115 forks source link

Sega Megadrive 2 cabling #405

Open G4DDS opened 1 month ago

G4DDS commented 1 month ago

Have been given a Mega Drive 2 and tried using a SCART lead (with another converter) but would prefer a crystal clear HD picture. From the cables section I see there are no consoles at all, but surely its just as a matter of wiring up the correct lead? The video pin outs have RGB, GND and CSYNC so is it just the same setup as an one of the existing Analog setups (like Amstrad or Spectrum +3):

Pin 1 GND Pin 2 SYNC Pin 3 BLUE Pin 4 GREEN Pin 5 RED

G4DDS commented 1 month ago

I've had a go but not making much progress. I have followed the Amstrad wiring and selected that as a profile. I kept getting a blank white screen but I discovered changing the DC coupling to AC (which I believe should only be used with YUV and not RGB) I get some sort of picture:

IMG_20241011_131438

I don't want to spend too much time and effort if I am going down the wrong path with this. Is the Amstrad wiring suitable? Is there another base profile that maybe better to work with?

IanSB commented 1 month ago

@G4DDS

This isn't really going to work well because the analog board can only discriminate 4 levels each of RGB but the palette of the megadrive has 8 levels each of RGB. With the correct profile you would get a reasonable image but colours might be slightly inaccurate or flickery.

Anyway, here are a couple of base profiles to try:

NTSC_4LVL_Base.txt PAL_4LVL_Base.txt

Put these in \Profiles\6-12_BIT_RGB_Analog_Base_Profiles and select the PAL or NTSC one as appropriate These have 4 level palettes selected but you will probably have to adjust the DAC levels for lo, mid and hi depending on the analog video levels output by the megadrive and you will also have to use the Create Custom Profile menu and Analyse Timing etc to get the settings right.

It looks like the video is analog RGB out of the video chip so it wouldn't be possible to pick up the digital bits directly like you can with some systems so the only other alternative would be a c0pperdragon style lumacode board if one was developed.

c0pperdragon commented 1 month ago

Sorry, but the Mega Drive is just out of reach of my possiblities and the abilities of the lumacode system.