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LCD problem on OMAP-L137

lousa
Prodigy 80 points
Other Parts Discussed in Thread: OMAP-L137

Hello everyone,

We use the arm to display in omap-l137 and use the dsp to calculate. We use some ddr memory as the display buffer, when we use the dsp operate the ddr address which not be contained in the display buffer address range, the imgage on the LCD could be affected.

Could anyone give a suggestion?
Thanks
Liu

  • 0
    TI__Guru* 83935 points

    Hi Liu

    Please note that OMAPL137 does not support DDR memory, it only support SDRAM (via EMIFB or EMIFA). LCD can only access SDRAM on EMIFB.

    I am not sure if you are actually seeing a problem, or if you are just concerned that using external memory as a shared resource between DSP and LCD could cause an issue.  Use of external memory by several masters in the SoC is a common and the device is architected such that the external memory bandwidth is adequate for typical/intended use-cases.

    You might find the concepts listed in the following wiki useful

    http://processors.wiki.ti.com/index.php/OMAP-L1x/C674x/AM1x_SoC_Architectural_Overview

    Regards

    Mukul

  • 0 in reply to Mukul Bhatnagar
    Prodigy 80 points

    Hi  Mukul,

    Thank you for your reply.

    Sorry for my inaccurate description before. I use the SDRAM as the LCD framebuffer.


    When i add a code "while( (LCD_STAT_REG | 1) == 0 );" before ARM write the framebuffer, the LCD displays correctly,
    and if i don't add this code, the LCD image moves. i think that code means the ARM is waiting for the DMA free,
    so it means that the ARM could opreate the framebuffer only when the DMA free. 
    But i think the ARM should operate the framebuffer at anytime and should not wait for the DMA free.
    Could you tell me what's wrong ?

    Thanks,

    Liu