Please help to fix the problem with screen on/off

greatkreator · Post by **greatkreator** » Wed Jul 22, 2015 3:04 pm

Please help to fix the problem with screen on/off

I am trying to turn off the screen in the first 16 lines of the screen in the top and the last 16 lines in the bottom to increase amount of data transferred in DMA with max speed.

There are no problems in the top with it but in the bottom the black line artifact appears.

Who knows how to get rid of that?

Thanks!

https://drive.google.com/file/d/0B0KLyA ... NaUm8/view

Stef · Post by **Stef** » Wed Jul 22, 2015 3:37 pm

You need to turn it back on at the correct time, so you should check for a specific H counter value before turning it ON again.

greatkreator · Post by **greatkreator** » Wed Jul 22, 2015 5:59 pm

Thanks a lot! It helped.

First time I tried to control turn off of the screen.
However it was needed to control turn on as you wrote.

greatkreator · Post by **greatkreator** » Thu Jul 23, 2015 2:20 pm

Stef wrote:You need to turn it back on at the correct time, so you should check for a specific H counter value before turning it ON again.

Now I have another problem: how to make the synchronization stable?
Few frames everything is excellent but some frame the screen shakes and then everything is ok.

I only do a DMA call in the (extended)vblank.
I guess that code that executes in the visible part of the screen don't "feet" in h counter timescale and it breaks the synchronization.