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signal of DMTIMER10_PWM of omap4460

CHIH-HAO CHEN
Prodigy 150 points

Hi 

I have a problem when Ｉam setting brightness in android system. I am using DMTIMER10_PWM of omap4460

to generate 15 KHz for lcd-backlight. Everything is fine when I setting brightness  0~254 except that  the brightness 255.

Sometimes omap4460 can generate PWM signal, but sometimes it can not generate PWM signal. By the way, I set

 the PWM signal of voltage is always high when I set brightness 255. Is there any protection when the omap4460 generate 

signal when voltage is always high??

Thank you

Jaden

  • 0
    TI__Intellectual 785 points

    Hi Jaden:

                There is no such protection in the omap4460 but the TRM mentions this,

    The GPT_TLDR and GPT_TMAR registers must keep values below the overflow value (0xFFFF FFFF) by
    at least two units. In case the PWM trigger events are both overflow and match, the difference between
    the values kept in the GPT_TMAR register and the value in theGPT_TLDR register must be at least two
    units.

               This will help you never reach such undesirable conditions.

    Regards,

    Rodrigo

  • 0 in reply to Rodrigo Castaneda
    Prodigy 150 points

    Hi  :

       Thank you for replying the question. I found that the problem was the evm board cound not support enough voltage.

    So the lcd panel has a little problem when I set  the brightness of 255. Thanks for replying the question. 

    Best regards. 

    Jaden