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ADV7181C  Non-supported resolutions

Question asked by Janos on Jan 17, 2011
Latest reply on Jan 26, 2011 by Janos

We would like to use the ADV7181C to capture non-standard input resolution.

I have seen AN-0978 that describes settings to use with ADV7401/ADV7403, also another document for AD9388A/ADV7441A chips.

 

The main difference was that there is an additional register "Line count max" for the AD9388A/ADV7441A chips, which I am missing for the ADV7401.

 

Let me describe my question. The MAC resolution example.

 

Info from the ADC point of view.

1, Step 1.

 

FR_LL[11:0] = 550dec = 0x226

So the

tLINE PERIOD =  20.36 µs

 

Conclusion:So the Hsync frequency is  49.107 kHz

 

2, Step 2.

 

PLL_DIV_RATIO[11:0] = 1120dec = 0x460

 

Conclusion:   - LPix per Line: 1120    

                    - Input frequency will be 1120x49.107 = 55 MHz

 

BUT

 

How it will find out that 49 107 lines are made from:

- 654 lines/frame x 75.087 frames/s

or any other combination?

eg. 720 lines/frame x 68.204 frames/s

 

CONCLUSION

 

I am missing some register, which sets the frame rate or the frame size?

Is it existing?

 

(Or is it calculating with the line count of the original setting, on which this is based on. Here:

PRIM_MODE = 0010b , VID_STD = 0100b for 800x600)


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