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Netra and Centaurus evm direct user GPIO

Manisha Agrawal
Mastermind 22946 points

Dear champs,

One of my customer has follwoing query-

 

I am starting to play with the GPIO on the evms. There is a couple of GPIO I2C expander but on our final product, we will directly use GPIO from the 81XX.

It looks like JP1 are user GPIO on the DVR extension board but I do not succeed to read their value from user space using this method.:

 

1. Is it possible to control OMAP GPIOs from userspace?

Yes, by using some nodes exported to sysfs. For example: To toggle GPIO155, do the following:

Mux the pad to gpio mode.

To bring out the gpio to userspace:

echo 155 > /sys/class/gpio/export

To set as an output:

echo out > /sys/class/gpio/gpio155/direction

To set high:

echo 1 > /sys/class/gpio/gpio155/value

To set low:

echo 0 > /sys/class/gpio/gpio155/value

Similarly cat these nodes to read the value of input gpios.

 

Is it possible to control the GPIO from user space?

Which one could I use for testing?

 

 

  • 0
    TI__Expert 6655 points

    Hi Manisha,

     

    Is it possible to control the GPIO from user space?

    Anil: One way to control the GPIO's from user interface is sysfs entries. If they need more details on sysfs entries then ask them to go through this post

    http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/717/p/130602/468956.aspx#468956

    Which one could I use for testing?

    Anil: This is entirely depends on their usage and H/w connections. Some of the GPIO line are not in use all the time and same pins are used for multiple purposes, based on the pinmux setting those IO pins are configure for a particular device.

    Check for the GPIO lines/pins which are not in use, then configure pinmux to get GPIO functionality and then probe the GPIO line for testing high/low values.

    Regards

    AnilKumar

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