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Two spikes in each line at 720p 24/23.98 Hz

Question asked by funried on May 5, 2015
Latest reply on May 26, 2015 by funried

Hi,

the ADV7391 generates two spikes in any line at 720p with 24 Hz or 23.98 Hz. All other formats work fine.

VSYNC_n, HSYNC_n and CLKIN are generated from a FPGA.

 

The attached screenshot shows C1: DAC1 and C2: HSYNC_n.

 

The register settings are:

0000000 1c20 2003 f04e 0e24 927c 0000 0000 0000

0000010 001b 0000 fa03 1f00 0000 0000 0000 0000

0000020 0000 0000 0000 0000 0000 0000 0000 0000

0000030 4800 0068 4800 a080 8000 0000 0000 0000

0000040 0000 0000 0000 0000 0000 0000 0000 0000

0000050 0000 0000 0000 0000 0000 0000 0000 0000

0000060 0000 0000 0000 0000 0000 0000 0000 0000

0000070 0000 0000 0000 0000 0000 0000 0000 0000

0000080 1000 0b04 0000 0200 0000 0c00 1f7c f021

0000090 0000 0000 0000 0000 0000 0000 0000 0000

00000a0 0000 0000 0000 0000 0000 0000 0000 0000

00000b0 0000 0000 0000 0000 0000 f26a 0042 8119

00000c0 1070 5e12 8026 4a70 8000 0000 0000 0000

00000d0 0000 0000 0000 0000 0000 0000 0000 0000

 

Has someone an idea what's wrong configured and should be changed to avoid the spikes?

 

Best regards

Franz

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