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L138 LCD Controller - support for Tearing Effect?

tehoaislimau
Intellectual 360 points
Other Parts Discussed in Thread: OMAPL138

Hello

Can the L138 LCD controller support TE signal from the LCD driver used to eliminate Tearing Effect for Smart (RAM) drivers with intel 8080 interface?

This TE signal is also known as FRAME_SYNC 

  • 0
    TI__Guru* 84075 points
    Hi Just so that I do not misinterpret, can you share a datasheet of what describes TE signal. I found something like http://www.techtoys.com.hk/Components/SSD1963QL9/SSD1963_1.1.pdf (Section 7.1.5) , and based on the description of this, we don't have a similar IO signal as an input to the L138 LCD controller. Regards Mukul
  • 0 in reply to Mukul Bhatnagar
    Intellectual 360 points

    Hello Mukul

    Yes, the intended singal of TE is similar to Section 7.1.5.

    Bascially its a V-Blanking singal to the MCU to indicate when to write data to avoid Tearing on the LCD.

    What you are saying is that, the L138 has no hardware capability to achieve this?

  • 0 in reply to tehoaislimau
    TI__Guru* 84075 points

    Yes, I believe there is no IO level capability to accomplish this with the LCD controller on OMAPL138. I think the onus would be on software and system bandwidth management to manage error reporting based on FIFO under-run generated error (FUF bit), which is asserted if the LCD DMA is not able to keep up the data rate consumed by the LCD.

    I am asking some additional display/LCD experts to sanity check this thread for me.

    Regards

    Mukul

  • 0 in reply to Mukul Bhatnagar
    TI__Mastermind 43875 points

    In the 8080 mode it should be possible to 'stall' the output under software control. It should then be possible to use the external v-sync/tear signal so trigger an interrupt which in turn initiates a frame display.

    This would give the same effect as the hardware tear signal, but would require some software intervention.

    Just a thought.

    BR,

    Steve