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Digital input/output linux

mike A
Genius 3490 points

Hi Mates,

 I have board which has digital in and digital out, Is there any support in linux (generic driver) which can be used to test digital i/o ? Or do I need to write a new driver for it ?

Thanks & Regards,

Mike

  • 0
    TI__Guru** 116100 points

    Hi Mike,

    What processor are you using ?

    You can use GPIO if you need digital input and output operations.

  • 0 in reply to Titusrathinaraj Stalin
    Genius 3490 points

    Hi Titus,

    I tried this link http://processors.wiki.ti.com/index.php/TI81XX_PSP_GPIO_Driver_User_Guide#Kernel_Level

    but the value is always 1 do I need to set the debounce timings ?

    Thanks & Regards,

    Mike

  • 0 in reply to mike A
    TI__Guru** 116100 points

    Hi Mike,

    gpio_direction_output(30, 1);
    gpio_set_value(30,0);
    gpio_get_value(30);
    gpio_set_value(30,1);
    gpio_get_value(30);

    You can use the above C API in linux kernel driver to change the particular GPIO value.

    http://projects.qi-hardware.com/index.php/p/nn-usb-fpga/source/tree/6caf52eff7e3126efa3468d2f6bd5e6a8e9d2fd5/Examples/drivers/blink/blinker.c

  • 0
    Intellectual 835 points

    You might get away w/o recompiling the kernel if sysfs with GPIO support is enabled.  See 

    http://processors.wiki.ti.com/index.php/TI81XX_PSP_GPIO_Driver_User_Guide#User_Space_-_Sysfs_control

    Also, make sure that the pin is set to GPIO.  If debugfs is enabled, you can do:

    mkdir /debug

    mount -n -t debugfs none /debug

    navigate to /debug/omap_mux

    To see the mux value, cat the pin.  For example:  cat gpmc_clk

    Make sure the mode is for GPIO