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ADV7393 Output Video Scrolling Vertically

Question asked by BenD Employee on Dec 17, 2013
Latest reply on Dec 18, 2013 by PaulS

I have a report from a cutomer that he is having trouble with the ADV7393 output video scrolling vertically:

 

We are feeding a 18bit (16-bit) parallel RGB565 signal to the ADV7393. We have PCLK = 27MHz, VS = 60Hz, HS = 15.6KHz. 

 

I have configured the ADV7393 with the values exactly as found in Table 77 (16-bit 525i RGB In, CVBS/Y-C Out).

 

We are seeing HSYNC and VSYNC coming from our board and going to the ADV7393 and they look good. The polarity was inverted on our side to work properly on the ADV7393.  After we corrected the polarity, the horizontal sync appears to be working fine.  We see a video source properly, but the video scrolls slowly vertically as if the vertical sync is not working correctly (not synced to the input VSYNC). We are seeing the same behavior on two separate boards with separate SSD3-MMB sources.

 

We are setting mode2 so I expect Figure 111 to be the correct timing. Can you please confirm that for Slave mode 2, that HSYNC and VSYNC (active low) are used, and not even/odd Field (as in Figure 108, mode 1)?  We are still seeing the signal not locked to the vertical sync coming into the ADV7393.  Initially we thought that we may need to use odd/even Field signal instead of VSYNC, but that does not seem to be what MODE2 requires. I am sending 0x0C to subaddress 0x8A, so I expect the ADV7393 is working in Mode2.

 

According to this information, it seems to me that the ADV7393 would be configured properly to receive active low HSYNC and VSYNC pulses as desired. I looked into the published example scripts, and the settings for Timing Mode 2 appeared to align with the settings in datasheet Table 77, except for one bit. In the datasheet, Register 0x8A bit 3 is described as "Reserved" with a value of "1", while it is set to "0" in the scripts (0x8A=0x0C in datasheet Table 77, but 0x8A=0x04 in the scripts). Is there any significance to this?

 

Can you please confirm whether the customer's understanding of the Timing Mode and settings are correct? Do you have any advice on anything else we should observe to help debug this issue? As we progress, I can offer more details offline, but I don't want to publish the customer's specifics in a forum.

 

Thanks,

Ben

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