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AD9389B/ADV7510: Unstable video for certain resolutions

Question asked by mra on Sep 12, 2012
Latest reply on Mar 1, 2013 by joe.triggs

For a long time we have had problems with certain formats when the video signal that is transferred over the HDMI cable includes sound.

We have observed it for 800x600@60, 1920x1080p60 (CVT timing with reduced blanking) and 1920x1200@60 on our own products and the evaluation board. As a preliminary solution, we switch to DVI mode for these particular formats, which gives a stable picture, but no sound. How can we solve this?

 

How to reproduce this bug on the Analog Devices ATV evaluation board:

__Test equipment__

- Analog Devices ATV Motherboard (Rev. B)

- Analog Devices EVAL-AD9388A/ADV744AFEZ_x (Rev. A)

- Analog Devices Video Output Board (Rev. B)

- BenQ E2400HD monitor with built-in speakers and BenQ G2400WDLCD monitor.

- QuantumData video test generator 881 (Test pattern: Audio 1, Source:

CVR1960D and DMT0860)

 

We connected a video generator to HDMI port A and a monitor to HDMI Output, and the script "Port A  RGB/YPrPb 444 25Mhz <  f < 160MHz 30Bit IN RGB 444 OUT through DAC/HDMI Audio through Tx FS = 48KHz" was loaded. When the input source is 800x600@60, we observe that the first few lines are flickering. When testing with 1920x1200@60, the entire screen is dark, but the picture flash every 5-10 seconds. If  we select the script "Port A  RGB/YPrPb 444 25Mhz <  f < 160MHz 30Bit IN RGB 444 OUT through DAC/HDMI Audio through ADAV803 Codec", which configures the evaluation board to not transmit sound information to the HDMI output, the picture is stable.

 

We have seen the same problem when we use ADV7604 as receiver and ADV7510 as transmitter on the evaluation board. If we tristate the audio output pins from the receiver (ADV7604, I0 map, 0x15 [4] = 1), the video becomes stable after a while.

 

Our workaround for AD9389b by setting the chip in DVI mode doesn't work the same way for ADV7510. It we set the transmitter in DVI mode  (ADV7510, i2c address 0x72, 0xaf [1] = 0), the output is more stable, but it is blinking every 5-10 sec, and there are some artifacts in the image.

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