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AM335x LCD Controller Hsync/Vsync vs DE

Jonathan Valdez
Genius 16565 points

Hello,

Background:

I am working with an AM335x processor and will be conencting it to a LCD display. IN the past I have used Hsync/Vsync approach, but now have 2 different LCD options. One supports HSync/Vsync and the other supports Data Enable for syncing.

Questions:

1) From my research on E2E, it appears as if the AM335x controller supports both sync methods (please confirm).

2) Are there any distinct advantages to choosing one method over the other? I have not been able to find any literature highlighting the differences.

  • 0
    TI__Guru**** 393215 points

    Hi Jonathan,

    Jonathan Valdez said:
    1) From my research on E2E, it appears as if the AM335x controller supports both sync methods (please confirm).

    Yes, the LCD_AC_BIAS_EN signal acts as DE for raster displays.

    Jonathan Valdez said:
    2) Are there any distinct advantages to choosing one method over the other? I have not been able to find any literature highlighting the differences.

    It's not a matter of advantage or disadvantage, it's a LCD display requirement.

  • 0 in reply to Biser Gatchev-XID
    TI__Genius 16565 points

    Thanks for the help.

    I have a follow up question that I cannot seem to figure out digging around the processor wiki (http://processors.wiki.ti.com/index.php/Sitara_SDK_Linux_LCDC).

    Where is the documentation on what will have to be done in the software to switch between these modes? Or will the PowerVR SGX kernel module from TI automatically detect and set the proper mode? Driver version in question is 5.01.01.01.

    Thank you,
    Jonathan

  • 0 in reply to Jonathan Valdez
    TI__Guru**** 393215 points

    The SGX has nothing to do with this. HSYNC, VSYNC and DE are all output in TFT Raster Display mode by the LCDC. You connect whatever is required to the display.

  • 0 in reply to Biser Gatchev-XID
    Intellectual 680 points
    Biser,
    Just for clarification purpose.

    The LCDC on the am335x outputs both HSYNC/VSYNC signals and a DE signal. And all we have to do is connect the correct signals (either the HSYNC/SYNC or the DE (alone iwth the RBG and clock signals) depending on whether the LCD supports SYNC or DE mode. Correct?

    Second question: I am using 7.0 SDK for the am335x. How do I know whether the LCDC is configured for Raster or LIDD modes? Is this done via DTS?

    thanks
    Peter