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Digital Video problem with TI TMS320DM6446 and AD ADV7343

Question asked by ErichNast on Dec 14, 2015
Latest reply on Dec 15, 2015 by DominicB

We are using the TI TMS320DM6446 to output VGA and DVI video. I am experiencing a lot of problems in getting this to work correctly.


TI TMS320DM6446

VGA 640x480:

The focus is currently on VGA. I am able to output VGA 640x480@60Hz. I also enable the internal colour bar of the DM6446 to have a standard reference to work with. I measured the signals coming out of the DM6446 using a logic analyser and they all fall within the timing specifications of this video standard. This is output from the DM6446 is fed into the AD ADV7343. See below for ADV7343 configuration. I am able to see the colour bars on the monitor connected to the VGA output, but the colour bar is shifted to the left by a few pixels. Approximately 25-30 pixels.

It looks like this : See attached pic


The register are show in the DM6446 640x480@60Hz txt file attached.


VGA 800x600@60Hz:

When I move over to this configuration, I don’t get any output on the monitor. The ADV7343 is configured as  described below.

The problem I have is that the HINT & HVALID registers don’t respond to the updated settings, They seem to remain at 640 pixels. All the other register and timings seem to work fine, but the data width between Hsyncs do not change. I think this is why I get no output on the monitor as it does not understand the timings with the short horizontal period. I tried this with other pixel clock rates as well, I get the same result.

The register settings are available in DM6446 800x600@60Hz.


I need to know why these registers are not responding as expected. I can’t continue with any other configuration until I have resolved this one.


The DM6446 is configured for SDTV output when they do VGA output whereas I get no output from the ADV7343 unless I configure the DM6446 for HDTV output. The AD device does not accept SDTV settings for RGB 24-bit input as far as I understand.



AD ADV7343

VGA 640x480:

I configure the ADV7343 for 24-bit  525p, RGB in, RGB out as per Table 98 of the datasheet. These seems like very few registers to configure.


VGA 800x600:

I configure the ADV7343 for 24-bit  625p, RGB in, RGB out as per Table 111 of the datasheet. These seems like very few registers to configure.



Any assistance in helping me understand what might be the problem with outputting digital video properly will be appreciated.