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jon2
jon2
Associate II
December 9, 2016
Question

STM32F746 Discovery - No PWM control of LCD backlighting

  • December 9, 2016
  • 3 replies
  • 1018 views
Posted on December 09, 2016 at 01:50

It looks like LCD_BL_CTRL is not connected to a PWM output-capable pin (PK3)?  Am I missing something?

    This topic has been closed for replies.

    3 replies

    Imen.D
    ST Technical Moderator
    December 9, 2016
    Posted on December 09, 2016 at 09:32

    Dear

    Magnussen.Jon

    ‌,

    Following the schematic in the

    http://www.st.com/content/ccc/resource/technical/document/user_manual/f0/14/c1/b9/95/6d/40/4d/DM001904pdf/files/DM001904pdf/jcr:content/translations/en.DM001904pdf

    LCD_BL_CTRL is connected to PK3.

    Could you please check this from your side andclarify more your feedback?

    Best Regards

    -Imen-

    In order to give better visibility on the answered topics, please click on 'Best answer' on the reply which solved your issue or answered your question. Thanks
    jon2
    jon2Author
    Associate II
    December 9, 2016
    Posted on December 09, 2016 at 13:28

    Yes, I mentioned that pin in my post.  However, it doesn't appear to be PWM capable, so it can only control on/off.

    ST Renegade
    ST Renegade
    Associate
    December 9, 2016
    Posted on December 09, 2016 at 21:37

    It appears you are right. The pin is not connected to Timer... Maybe it would be possible to connect the PK3/LCD_BL_CTRL to a timer output on the board using a jumper wire or so.

    Have a nice day,

    Renegade

    PS: Maybe you can use DMA to transfer data to the GPIO output and create your own PWM out of it triggered by some timer or so if you prefer SW solution.

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