Hello AVGA-ers,

I recently decided to change my AVGA test circuit around to use a PAL TV instead of a VGA monitor. I never really got around to implementing something proper on AVGA, so I stuck with the tutorial example.

My circuit runs on 25mhz and the tutorial runs fine on VGA.

I wired up a SCART connector, plugged it into the breadboard alongside the VGA connector (with one SYNC line missing) and made sure that pin 16 was wired up to an appropriate voltage.
I then reconfigured the tutorial app; changed video_init(VGA2) to video_init(PAL) and changed the required settings in config_screen.h. Recompiled using the same settings I used for the VGA version (same hardware, basically) and turned on the TV.

It does work, somewhat, the tutorial appears on the screen and plays as expected, the colours are fine, but the positioning isn't... The entire picture keeps moving across the screen horizontally, going faster and faster. Eventually it stops and starts moving the other way. Sometimes it moves slightly diagonally.

This tells me there is something off with the timing, but I'm not familiar enough with the inner workings of all this to figure out what it is or how to change it. So I'm hoping someone here can shed some light on that...

I'm from the Netherlands, my TV is a regular PAL one as far as I'm aware. It also accepts a PAL60 signal from my DVD player, if that means anything.

Finally, I'd like to note that Vedder is right about optimizations in this topic; viewtopic.php?f=6&t=18. There really does seem to be a difference. With O0 or Os, I get no picture at all. With O1, O2 and O3 the picture moves, but the speed and direction change drastically depending on which optimization is used.

Does anyone have a clue how to stabilize the picture on my TV?

Hi,

This looks there's no sync at all. Make sure that you've connected the HSYNC output pin correctly to the scart connector (composite video input).
You can also try ver 0.21 which is preconfigured to PAL. No problems has been with PAL sync so far...

Good luck