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Toggelin a GPIO

Ali Movahedi
Intellectual 840 points
Other Parts Discussed in Thread: AM3517

Hello,

My main question is what are the registers involve to toggle  a GPIO in AM3517 ARM processor.  I am basically interested to toggle the GPIO-140.  One quick sample or a reference would be very useful.  I also like to know how I can do this in U-Boot please.

Thanks,

Ali.

  • 0
    Expert 2060 points

    Hi Ali,

    check in u-boot ;

    board/ti/beagle/beagle.c file.

    you may get some idea!!!!!!!!!!!!!!!

    Regards,

    santosh vastrad

  • 0 in reply to santosh vastrad
    Intellectual 840 points

    Dear Santosh,

    Thank you for your suggestion.  Please let me know if this is the correct path to the file that you suggested,

    http://gitorious.org/beagleboard-validation/u-boot/blobs/xm/board/ti/beagle/beagle.c

    I am trying to set a GPIO let's say GPIO-140 to high and low.  I already tried the following command,

    cd /sys/class/gpio/

    echo 140>export

    cd gpio140

    echo out > direction

    echo 0 > value

    echo 1 > value

    By entering the above command I did not see the GPIO_140 toggles.  I found out I may need to set the MUXMODE as well.   Basically would you know how I can enter the following command in as suggested  in

    http://elinux.org/BeagleBoardPinMux#OMAP3 please,

    MUX_VAL(CP(MCBSP3_DX), (IEN | PTD | DIS | M4)) /*GPIO_140*/\

    Thanks again,

    Ali.

  • 0
    Expert 1205 points

    Hi Ali,

    Refer to the below list of functions present in:  "cpu/arm_cortexa8/omap3/gpio.c"

    omap_request_gpio

    omap_set_gpio_direction

    omap_set_gpio_dataout

    Regards,

    N.S.SriHarsha

  • 0 in reply to santosh vastrad
    TI__Intellectual 975 points

    Dear Ali,

    You can refer to function "setup_net_chip" inside "board/ti/evm/evm.c" which actually toggles Eth reset gpio pin.

    The evm.c code is located under <u-boot home directory>/board/logicpd/am3517/am3517evm.c OR if its older u-boot version then check <u-boot home directory>/board/ti/am3517/am3517evm.c

    Let me know if this helps.