Finding the Project

After seeing the 240p test suite everywhere I wondered if a standalone RGB test pattern generator existed, and sure enough as usual someone has already figured it out. I found this project on ‘AVR Projects by Dim’ that uses an ATTiny 2313 chip to generate 13 image patterns and a 1khz sound tone. So as usual I ordered some boards.

Figuring out what I did wrong

Other than finding the 2313 chips, everything else was pretty easy to put together. Programming it was easily done with the TL866 II programmer and using the included fuse settings. And then I found a problem, there was no sync on any of my PVM’s. Trolling through the comments, it became apparent I was not the first one to have this issue. I found the below comment buried in the comments.

“Try to change speed of clock with Quartz as close as possible to 21 Mhz. I’d had the same problem and I change a quartz with 20.8333 Mhz and now the generator works OK !
With 14,880 Hz is the Sync too slow for cca 5% ! Now with faster quartz I get 15,500 Hz Sync wich is within 1% of tolerance to needed 15,625 Hz.”

So I needed a 21mhz crystal, easier said than found. But as usual it was AliExpress to the rescue again. Ordered a bunch of crystals either side of 21mhz just to be sure, but I put it in and it ‘just worked’. 

Getting it working and boxing it up

Once it was working I just had to find a box, some from Jaycar suited well and it was just a matter of cuttings some holes. I opted to externally mount the buttons and run it all off a 9V battery ( even though it wanted 12V, its regulated to 5V anyway ).