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TFP401/3 for DVI->MIPI

John Leung
Prodigy 30 points
Other Parts Discussed in Thread: TFP401, TFP403, TFP401A, TFP501

Sirs

I am working on a project to connect a mobile phone LCD screen to HDMI port. No audio is required so, I only have to deal with the video signal. This makes TFP401/3 a good choice to use.

The LCD screen is a 720 (horizontal) x1280 (height) MIPI panel. I already have a master mipi bridge (SSD2828) successfully driving this LCD screen in portrait mode 720x1280. This SSD2828 accepts 24-bit RGB input and output 4-lane mipi for the mobile phone display.

There remains to find TFP401/3 to sink TMDS from a PC and get it converted to 24-bit rgb for SSD2828.

But I don't understand EDID. From a reference design of TFP403 (SLLA134) I can see that pins 92/93 are DDC_SCL and DDC_SDA. They are connected to pins 6&7 of a DVI port with net labelled as EDID_SCL & EDID_SDA. Questions are:

1. Does it mean I need to connect an external mcu or EEPROM to EDID_SCL & EDID_SDA to store 256 bytes EDID information including the LCD resolution and clock rate, etc?

2. If answer to question 1 above is negative, how the PC "knows" what video resolution to output matching my LCD screen?

3. Does the circuit on SLLA134 work with HDMI with no audio signal? DVI port on a laptop is less common nowadays.

4. Does the reference design on SLLA134 works with TFP401A too?

5. Read from another post that TFP401/3 does not care about the resolution standard as long as pixel clock speed is within limit. Does it mean a 720x1280 portrait output from a PC can work?

Regards

John

  • 0
    TI__Guru* 76130 points

    Hello,

    For Q1 and Q2:

    The TFP401 is not really involved on the EDID exchange, the DDC lines on the reference design you are watching are actually for the TFP501 which incorporates HDCP, those lines are not used with the TFP401.

    Yes, you need to h ave an EDID ROM to store the display information, as you say, this is how the PC knows the capabilities of the sink.

    Q3: Yes, the TFP401 works with HDMI with no embedded audio.

    Q4: Yes

    Q5: Correct, as long as the pixel freq is within limits, it will support any resolution.

    Regards

  • 0 in reply to Elias Villegas M.
    Prodigy 30 points

    Elias, thanks.

    Further questions :

    1. I need to use EDID because the board will need to support different resolutions. No HDCP is required so, I believe TFP403 is the correct part number to use. Again, from SLLA134, pins 92 to 94 are labelled with DDC_XXX that I am not sure what is the features. Data sheet of TFP403 marks theses pins to be reserved. How to use DDC_XXX on TFP403?

    2. Are pins 95 and 96 for HDCP EEPROM? They are marked as reserved on datasheet as well.

    John

  • 0 in reply to John Leung
    TI__Guru* 76130 points

    Hello,

    All the connections and sections in "red" on that literature apply only for the TFP501, all those pins are not used on the TFP403.

    Regards.