larsbrinkhoff
commented
8 years ago The demo uses two different methods to remove the lower border:
- Triggering a Timer B interrupt at line 199, switch to 60 Hz, busy-wait, and switch back.
- Triggering a Timer B interrupt at line 199, switch to 60 Hz. Trigger another interrupt at the next line, and switch back.
In addition, the F1 screen also switches from medium to low resolution after going back to 50 Hz. This puts an additional timing constraint on the interrupt, because this switch must happen before the DE signal.
It's possible to adjust the timing of the Timer B interrupt back and forth to find a window where the first method works. But it's more difficult to make the second method work, especially in combination with the first.
I believe the problem getting Phalanx Demo to work (see #77) is related to a missing MFP interrupt latency.