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ADV7842: Big jitter on LLC for HDMI FreeRun mode

Question asked by Sasa on Jan 20, 2016
Latest reply on Jan 21, 2016 by GuenterL

Hi

 

I see very big jitter on LLC when HDMI works in the FreeRun mode. Why?

LLC = 74.25MHz (720p, 1080i).

PRIM_MODE[3:0]=5,

VID_STD[5:0]=0x13 or 0x14 (for 720p or 1080i)

 

Component input works well in the FreeRun mode - jitter is absent!

PRIM_MODE[3:0]=1,

VID_STD[5:0]=0x13 or 0x14 (for 720p or 1080i)

 

I set “DIS_AUTO_PARAM_BUFF=1”, (CP.0xC9=0x2D) – “Free run standard determined by PRIM_MODE[3:0], VID_STD[5:0] and V_FREQ[2:0] (p.375)”.

But “HDMI_AUTOPARM_STS[1:0]=b10 (CP.0xE0=0x21) – “The CP is free running according to the HDMI buffered parameters”. Why? It must be b00 – “The CP is free running with according to timing parameters programmed in PRIM_MODE and VID_STD”.

 

Thanks,

Alexander

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