Access PWM 1-6 from A9

Discussion in 'UDOO NEO' started by maleadt, Feb 21, 2016.

  1. maleadt

    maleadt New Member

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    Hi all,

    I want to PWM 3 (or possibly more) pins from the A9, and according to the pinout there should be 6 PWMs available. However, following the documentation and using the device tree editor to enable the PWM feature, I can only enable PWM 2 and 5.

    How do I enable those other PWM channels?
     
  2. maleadt

    maleadt New Member

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    Also, is there a way to determine which pins /sys/.../pwmchip$X/pwm$Y correspond to?
     
  3. maleadt

    maleadt New Member

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    Looking at imx6sx-udoo-neo-externalpins.dtsi which dtweb ships, PWMs 1 to 6 are defined and available. Is there a reason the web interface only allows access to PWMs 2 and 5?
     
  4. waltervl

    waltervl UDOOer

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    If you edit the /opt/dtweb/public/boards/neo/board.js file you can add the other pwm pins manually. You have to take care of the pin numbering as in the mentioned pinout documentation.
    Then you can use dtweb to set them.

    I do not know why they are not yet listed in dtweb. Perhaps there are some conflicting ports? But if you give it a try we all can benefit of it :)
     
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  5. maleadt

    maleadt New Member

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    I just want to make sure the pins aren't disabled for a good reason, ie. enabling them in the -dist dt will not blow up my udoo...
     
  6. Francesco

    Francesco Active Member

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    Yes, the good reason is that the SoC has 8 PWMs.
    6 PWMs are assigned to the Arduino core, 2 to Linux.

    If you want to use the other PWMs you must disable the M4 core, or rebuild MQX disabling the PWM capability of Arduino.
    Adding the other PWMs to the device tree (without turning off M4 - with udoom4ctl) you would expect bad behaviours (eg. kernel panics) but the hardware will not blow up.
     
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  7. longhongc

    longhongc New Member

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  8. waltervl

    waltervl UDOOer

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  9. hiten

    hiten UDOOer

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  10. waltervl

    waltervl UDOOer

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    Why are you running Android OS?
     
  11. hiten

    hiten UDOOer

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    because my project is android based
    like example:- using the android os control board peripherals
     
  12. hiten

    hiten UDOOer

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    waltervl likes this.

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