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How to configure PPI/DMA (Blackfin 537) when using an ADV7280 in I2P-mode?

Question asked by kristoffer on Aug 22, 2016
Latest reply on Aug 26, 2016 by JeyasudhaMuthuPerumal



I have a custom PCB where an ADV7280 is connected to an Blackfin 537 (PPI). I currently feed the ADV7280 with PAL and the Blackfin weaves the interlaces frames into a frame buffer - this works properly.


When enabling the ADV7280 I2P-functionality I follow the same procedure as the script ":I2P FAST SWITCH PAL Single Ended In Ain1, YPrPb Out (576p EAV/SAV):" - set VPP address, enable the advanced timing mode and the deinterlacer. Reading the VPP registers after the writes yields the expected values.


However the Blackfin doesn't seem to get any data after enabling I2P. I suspect that it is the PPI configuration that is faulty but I have tried different PPI and DMA configurations without any luck. Examining the PPI/DMA registers indicates no errors.


So my main question is what is the proper way to configure PPI/DMA (Blackfin 537) when using an ADV7280 in I2P-mode?


If it isn't likely that it is the PPI/DMA configuration that is the problem then I guess it's something with the ADV7280. But given there seems to be no problem writing/reading the VPP map, where should I start looking for issues?


My current settings for interlaced operation (also attaching a screenshot of the register values):
PPI_FRAME = 625;
PPI_COUNT = 1439;
PPI_CONTROL = ITU-R 656, active field only. Both fields. Packing enabled. Skipping enabled (only use grey scale).


DMA: Configured using DMA descriptors. Weaves Frame 1 and 2 into a frame buffer. (This deinterlace operation obviously should be removed, but I suspect the DMA engine never even gets any data.)

X_COUNT = 360;

X_MODIFY =  2;

Y_COUNT = 288;

Y_MODIFY = 722;