Hi
We use a DM6446 with a ADV7343 connected via a 8-bit BT.656 bus to generate SD video (sync on green RGB, PAL B Y/C and PAL B composite).
Our problem is that we get a negative pulse at the end of the line blank period as can be seen on the attached scope capture 1. The black level of the front and back porches are not at the same level. The oscillation on the back porch is due to dc restoration to force the blank level to 0 Volt. Channel 1 is the green output signal and channel 2 is the red output signal.
The Y/C and composite outputs have got similar problems. See scope capture 3. Channel 1 is the composite signal and channel 2 is the Y signal of a Y/C pair.
In scope capture 2 channel 1, lines 23 and 24 the green video data goes below 0 Volt.
It seems that the encoder tries to display a color that generates this phenomenon.
Changing the HSTART and HVALID values in the DM6446 has no effect.
Does anybody know how to fix this problem?
