Video Signals for Newbies: CSYNC

[NivagSwerdna]

I'm trying to build a simple test pattern generator using a rpi 2040 (aka pico) and using the scanline functions have managed to get seperate HSYNC and VSYNC working at my desired 15.6kHz scan rate... visible area is 256x224

Now I need to move on to making Combined Sync (since this is what one of my monitors supports)...

Looking at several arcade schematics I see nHSYNC AND nVSYNC used for nCMPSYNC

I could do this... but then I saw a video where the HSYNC was present during the VSYNC period but inverted?

Please could you point me at something that defines what composite sync should look like!

Thanks in advance

[Brianf]

Here you go. (assuming that you want PAL).

If you need NTSC, just shout.

[Terry Bites]

See hackaday.io/project/161006-yet-another-vga-to-scart-adapter/details

[wasedadoc]

It is impossible to make PAL or NTSC spec composite sync from the two HSync and VSync signals you already have.  Full spec requires equalising and broad pulses which are at twice line rate.

Having said that, most TVs and TV monitors will function adequately when given an AND of negative going HSync and VSync.

[strawberry]

or maybe SECAM

[Benta]

If you have 40 Euro to burn,
Keith Jack, "Video Demystified" is the way to go. One of the best books in my library.