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ADV7842: Detecting CVBS vs. S-Video

Question asked by KevinL Employee on Mar 1, 2011
Latest reply on Mar 2, 2011 by raymondcarter

With an S-Video input, using script from script file ADV7842-VER.5.9c.txt:

:1-2b S-Video NTSC_PAL-M 480i 10bit H_V Encoder:


I find that register:






, Addr 90 (SDP), Address 0x54[5] (Read Only)

      0 = CVBS input is detected

      1 = Y/C input is detected


always shows a value of 0 = CVBS input is detected.


I have checked the script, refreshed the reading of this status register, ...

and I have exercised it with both CVBS and S-Video, and with both color and B&W.  In all cases, the bit value is 0.


I also checked the input muxing to verify that it adheres to the following text from the HW manual. The input muxing is correct in the above mentioned script.



"Note that when selecting analog input routing to the ADCs the following rules must be adhered to:

The CVBS, Y or G signal must be routed to ADC0

The C signal in S-Video( YC) mode must be routed to ADC2"


The hardware platform is the ADV7842 VIM / ATV MB / VOM Rev E. I have verified that Y goes to input A10, and C goes to input A12, and that these are routed to ADC0 and ADC2 properly by the script.


Any ideas why SDP_C_CHAN_ACTIVE does not work properly? Or, is there another way to detect S-Video vs CVBS?