GPIO always returns "Device or resource busy"

[Jeremy Darling]

Like (many) others I'm trying to play with the GPIO on the Rock.  Seems though that no matter what I do though I get the same response "Device or resource busy"

I'm running the Ubuntu 14.04 distro from the website.

Reading all over the web I can find that it seems I may need to enable the GPIO config in the kernel.  No clue how to do that, anyone have a line by line tutorial on how to do this?  Or, is there something else I should be trying?  I've tried su'ing the led.sh file and running it under su as root.

output from led.sh

led.sh: line 4: echo: write error: Device or resource busy

source of led.sh (from wiki)

#!/bin/sh

# enable the gpio 172 -> green led

echo 172 > /sys/class/gpio/export

# set the direction to output

echo "out" > /sys/class/gpio/gpiochip172/direction

while true;

do

echo 0 > /sys/class/gpio/gpiochip172/value #led on

sleep 1

echo 1 > /sys/class/gpio/gpiochip172/value #led off

sleep 1

done

Thanks,

 - Jeremy

[Tom Cubie]

This is because the gpio for the led is occupied by the kernel. You
can not control it via the gpio interface. You can control the led via
the led class. http://wiki.radxa.com/Rock/led

If you want to control the gpio, you can use the spare ones on the
extension header.

>
> Thanks,
> - Jeremy
>
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radxa rock - quad core arm computer that rocks

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[Naoki FUKAUMI]

On Fri, Sep 19, 2014 at 11:35 AM, Tom Cubie <t...@radxa.com> wrote:
> If you want to control the gpio, you can use the spare ones on the
> extension header.

I'm not sure, but I guess some redundant kernel config option may
occupy GPIO control from userland... if it's true, defconfig needs to
be cleaned.

[Jeremy Darling]

One more question, is there a picture like below:

Only with the pin #'s on it?  I'm guessing that the mapping is something like:

RK30_PIN0_PA0 = (0*NUM_GROUP + PIN_BASE + 0) = HOST_DP2

RK30_PIN0_PA1 = (0*NUM_GROUP + PIN_BASE + 1) = HOST_DM2

RK30_PIN0_PA2 = ... = LINE_L

RK30_PIN0_PA3 = ... = LINE_R

etc...

 - Jeremy

[Tom Cubie]

On Fri, Sep 19, 2014 at 11:04 AM, Jeremy Darling
<jeremy....@gmail.com> wrote:
>
> One more question, is there a picture like below:
>
>

> Only with the pin #'s on it? I'm guessing that the mapping is something like:
>
> RK30_PIN0_PA0 = (0*NUM_GROUP + PIN_BASE + 0) = HOST_DP2
> RK30_PIN0_PA1 = (0*NUM_GROUP + PIN_BASE + 1) = HOST_DM2
> RK30_PIN0_PA2 = ... = LINE_L
> RK30_PIN0_PA3 = ... = LINE_R
> etc...

some(most) pins on the extension header cane be used as GPIOs, but
some can not, such as LINE_L and LINE_R are the analog signal.
HOST_DP2 and HOST_DM2 can not be used as GPIO too. It's connected to
the USB hub.

> To view this discussion on the web visit https://groups.google.com/d/msgid/radxa/CAAhs7EiX%2BhPS05L5ZnMQPWdENxbg-mTA2-77HFh7t2n%2BhdbfLg%40mail.gmail.com.

[Jeremy Darling]

Guess that makes my question even more, is there a pinout document/diagram showing what pin's are available and what their effective number is?

Basically we have a Meetup next week in our local Node.js group talking about hardware hacking and Node.js with different dev boards.  I was going to show off the Rock blinking a few leds, running some servos, checking light levels from sensors, etc...  But would have to know exactly what can and can not be done :)

BTW: It makes a great little web server LOL

 - Jeremy

[Jeremy Darling]

After some digging on talk.radxa I stumbled across this post http://talk.radxa.com/topic/476/gpio-to-pinout-legend/4

To anyone else, that is the pinout mapping for the rock :)

Should add that to the wiki on the GPIO page too.

[Tom Cubie]

On Fri, Sep 19, 2014 at 11:28 AM, Jeremy Darling
<jeremy....@gmail.com> wrote:
> After some digging on talk.radxa I stumbled across this post
> http://talk.radxa.com/topic/476/gpio-to-pinout-legend/4
>
> To anyone else, that is the pinout mapping for the rock :)
>
> Should add that to the wiki on the GPIO page too.

Added to the http://wiki.radxa.com/Rock/extension_header page.

> https://groups.google.com/d/msgid/radxa/CAAhs7Eh-meHjY3cEsQOFNf67BmTM1QGfG_2nDuy7GFN4GfL%2BoA%40mail.gmail.com.

[Jeremy Darling]

Tom, any chance you can post the code to interact with the GPIO using registers instead of file handles?  You said something about it the other night and I'd like to try and use that approach with the library I'm working on.

 - Jeremy