config-pin for gpio output

[Mark A. Yoder]

In the day I did:

config-pin P9_11 out

to make it a gpio output.  Now it appears I have to do:

config-pin P9_11 gpio

But how do I make it an output?  Must I do:

echo out > /sys/class/gpio/gpio30/direction  ?

--Mark

[Robert Nelson]

The concept of out/in is not currently supported in the c based
re-write of config-pin used in Buster..

https://github.com/beagleboard/bb.org-overlays/tree/master/tools/pmunts_muntsos

https://github.com/beagleboard/bb.org-overlays/blob/master/tools/beaglebone-universal-io/config-pin#L1088-L1108

Regards,

--
Robert Nelson
https://rcn-ee.com/

[Mark A. Yoder]

So is,  
 echo out > /sys/class/gpio/gpio30/direction

The proper way to set it to output?

--Mark

On Wednesday, June 3, 2020 at 9:45:00 AM UTC-4, RobertCNelson wrote:

[Robert Nelson]

On Wed, Jun 3, 2020 at 9:15 AM Mark A. Yoder <mark.a...@gmail.com> wrote:
>
> So is,
> echo out > /sys/class/gpio/gpio30/direction
>
> The proper way to set it to output?

The proper way is to use libgpiod tools such as gpioset ;)

sudo gpioset gpiochip0 30=1

But that old way still woks.

[Mark A. Yoder]

Well, my solution, for now, was to write a wrapper[1] for config-pin that uses gpioinfo when 'in' or 'out' are used.

--Mark

[1] https://github.com/MarkAYoder/PRUCookbook/blob/v2.0/docs/common/config-pin.sh

On Wednesday, June 3, 2020 at 10:27:38 AM UTC-4, RobertCNelson wrote:

[TJF]

Am Mittwoch, 3. Juni 2020 16:27:38 UTC+2 schrieb RobertCNelson:

The proper way is to use libgpiod tools such as gpioset ;)

The proper way is to use libpruio and do pinmuxing single source in the code ;)

pruio_gpio_setValue(io, P9_11, [0,1]);

Regards

[Drew Fustini]

How does the library change the pinmux during runtime?

Does it use /sys/devices/platform/ocp/ocp:P9_11_pinmux/state? (which
is created by bone-pinmux-helper)

thanks,
drew

[Daniel Kulp]

The GPIO utils in FPP use a combination of /sys/devices/platform/ocp/ocp:%s_pinmux/state and /sys/class/gpio/gpio%u/ locations to configure the pin in various ways.   See:

https://github.com/FalconChristmas/fpp/blob/master/src/util/BBBUtils.cpp#L228

Some of it is a bit complex as some pins may need to boot up in i2c mode but then be flipped to gpio/out. 

The idea of using libgpiod is "ok" but doesn't allow configuring the internal pull ups for the input (at least until kernel 5.4 and a newer version of libgpiod)

Dan

[TJF]

Am Freitag, 5. Juni 2020 13:06:48 UTC+2 schrieb Drew Fustini:

How does the library change the pinmux during runtime?

It contains a LKM (loadable kernel module) that can set any pin configuration (ie. PRU-GPIO with pull-[up,down] at SD card slot) at run-time. All members of system group "pruio" have pinmuxing access from user space. This concept saves lots of kernel memory and more than six seconds boot-time.

Check out the documentation.

Regards