Video pattern generator

[moki]

I am looking for a circuit for a video pattern generator. All I need is a color bar pattern and cross hatch. I repair video game monitors as a hobby. Most of the monitors I repair are 15khz and have R,G,B,gnd and synch inputs. I have bought a CHECKER 12 pattern generator from Computer & Monitor Maintenance Inc. for computer monitors. This one works with the high resolution video game monitors as well as computer monitors, but does not work with the 15khz video game monitors. I am currently using a Capcom Gold video game board which has a test position for Color Bars and Crosshatch. I would like to build a dedicated pattern generator. Any help would be appreciated.

 

[HarveyH42]

Not sure how professional, but saw this done with an AVR microcontroller and a couple of resistors. Think it was about a year ago, but pretty sure the code and schematic were on the site. Will make a quick search later and see if I can dig it up. Not sure if you can do it with a PIC ...

**broken link removed**

Not the one I remember, but looks better, and uses a $2.00 AVR chip (ATtiny2313) instead. Might build one myself.

 

[Nigel Goodwin]

Not sure how professional, but saw this done with an AVR microcontroller and a couple of resistors. Think it was about a year ago, but pretty sure the code and schematic were on the site. Will make a quick search later and see if I can dig it up. Not sure if you can do it with a PIC ...

I've got a colour bar generator I built using a PIC.

But at work I've got an AVR based one, which I built from a kit, following a project in Television Magazine, it generates various patterns and test cards.

 

[HarveyH42]

I've got a colour bar generator I built using a PIC.

But at work I've got an AVR based one, which I built from a kit, following a project in Television Magazine, it generates various patterns and test cards.

I use AVR, so I tend to pay more attention to AVR projects, although I do look at PIC (how the hardware is wired) occasionally. I have seen video generated with pick, but it was PAL and text only.

After posting the link, I went back to read in more detail, seems like an easy build, and could use one. Although I've gone LCD, got a couple of CRT monitors I would mind getting fixed as backups. I was wondering about the 15khz from the original post. Not sure what he was referring to.

 

[Nigel Goodwin]

I use AVR, so I tend to pay more attention to AVR projects, although I do look at PIC (how the hardware is wired) occasionally. I have seen video generated with pick, but it was PAL and text only.

After posting the link, I went back to read in more detail, seems like an easy build, and could use one. Although I've gone LCD, got a couple of CRT monitors I would mind getting fixed as backups. I was wondering about the 15khz from the original post. Not sure what he was referring to.

Line speed on PAL is 15,625Hz - so probably that?.

 

[moki]

The 15Khz I was referring to is the Horizontal scan frequency which is actually 15.72
KHz.

 

[moki]

Have a look at this website to get an idea of a standard video game monitor timing:

Embedded Mame