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Square pixel mode in adv7170

Question asked by LucasRotava on Dec 13, 2010
Latest reply on May 18, 2011 by DaveD

Hello, I'm working with the adv7170, wich is comunicating with an FPGA. My adv7170 is working in mode 0 (EAV/SAV) for 525/60 video systems, and it is working well in the non-square pixel mode, but my application requires a 640x480 resolution, and the square pixel operation is not working well.

I've set the subcarrier frequency registers to x"25555555", and my input clock is 24,55MHz.

I am also using the data format from this application note http://www.intersil.com/data/an/an9728.pdf (the data format for square pixel).

 

But when I start to play the video, the screen shows the image for a short time, and then the screen goes blank for a time, then it shows the image again. It keeps blinking. It seems that it´s loosing sync somewhere.

 

I think the problem can be in my data format, but I can´t find any application note that teaches me about square pixel operation with the adv7170.

 

So, did I forget something in my configuration? Is this data format from the intersil´s application note correct?

 

[Edit]

Apparently, changing the subcarrier frequency registers does not change anything in my problem. I tried diferent values and the results was apparently the same. So, maybe my register programming is not right. Anyway, what means this subcarrier frequency registers value (No of Subcarrier Frequency Values in One Video Line)?

 

The image attached is the i2c signals of the registers programming. Between the 2 black bars you will see the subcarrier frequency registers programming, wich is suposed to be using the auto increment.

 

Thank you in advance.

 

Lucas

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