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TFP410 will not display an image on most HDMI devices

Kevin Pasko
Prodigy 20 points
Other Parts Discussed in Thread: TFP410

The TFP410 is currently hooked up to an HDMI connector and has been tested on both HDMI and DVI televisions / monitors (using the appropriate HDMI -> DVI connector). The TFP410 works fine on all the DVI monitors, displaying an image. Though it would not display an image on most HDMI televisions, yielding "Invalid Format" even though it was providing a valid video format (ex: 1280 x 720 @ 60Hz). According to the HDMI spec, all HDMI devices should be compliant with DVI 1.0.

The TFP410 is configured as follows:

After doing some troubleshooting I found that the monitors that displayed an image properly had detected both a receiver and monitor by checking the RSEN and HTPLG bits. The monitors / televisions that did not work only detected a receiver and did NOT detect a monitor with HTPLG.

Any ideas?

  • 0
    TI__Mastermind 20985 points

    Hi Kevin,

    So after plugging in a monitor that doesn't work, if you measure the HPD line, is it a low voltage?  If so, that means the monitor never decided to drive it high.  I believe a monitor pulls HPD high once EDID is ready to be read.  The graphics processor is what communicates with the monitor via I2C (DDC).  As a guess, maybe the graphics driver lacks the mode that the monitor requires.

    Best regards,
    RE

  • 0 in reply to RE
    Prodigy 20 points

    RossE,

    Thanks for the quick response. When plugged into an HDMI television that doesn't work the HPD line is a low voltage. As shown in the schematic I posted in my original post the SCL, SDA, and +5 pins (DDC signals) are disconnected.

    According to the DVI spec's monitor hot plugging requirements, the monitor must provide a voltage greater than +2.4V on the HPD pin ONLY WHEN the EDID is available to be read by the host, a low voltage indicates the cannot be read. Since the HDMI spec supports DVI 1.0 this should apply to this situation.

    So far I've been able to connect the board into various HDMI and DVI monitors with successful results. Could the DDC lines be required (even if the sink claims the EDID is not available for read)?

    Thanks,
    -Kevin

  • 0 in reply to Kevin Pasko
    TI__Mastermind 20985 points

    Kevin, I think I have your answer.  Some monitors power their EDID circuit internally, leaving HPD always high.  Others require 5V from the connector before pulling HPD high--those are the ones not working for you.  I'm not sure if merely tying HTPLG high on your board will make those monitors work, or if you need to provide 5V to the connector; you could try both.

    Best regards,
    RE