[PD] gpio on the raspberry pi from within pd ?

[Julian Brooks]

BTW - Forgot to add:
I did read through this thread (as mentioned by Charles):
http://www.raspberrypi.org/phpBB3/viewtopic.php?f=29&t=9667&p=198848
And left none the wiser...
Seemed to me that there are several possible implementations, though I am
completely unsure as to which one would work with the /sys/class/gpio/
method that [gpio] makes use of?

I think I'm going to be asking several possibly dumb questions around gpio
until I can get my head around all this so apologies up-front.

Julian

J



On 2 April 2013 09:46, Julian Brooks <jbeezez at gmail.com> wrote:

> Hi Charles / list,
>
> Can I ask you/anyone a question re: permissions for accessing the gpio
> pins please?
>
> Currently I can't get past:
> "echo gpio17 > /sys/class/gpio/export"
> which gives me "permission denied" with everything I've tried.
>
> Are you using WiringPi to allow access to the gpio and if not how?
>
> I'd like to stick with Miller's [gpio] object
> http://crca.ucsd.edu/~msp/syllabi/206.13w/index.htm
> (found in the earlier split thread - apologies for the noise)
> and keep as much within Pd as possible.
>
> Best wishes,
>
> Julian
>
>
> On 28 January 2013 14:14, Charles Goyard <cg at fsck.fr> wrote:
>
>> Hi list,
>>
>> I could make use of gpio (as output) within pd with just [textfile] :
>>
>> on the command-line:
>>
>> echo gpio17 > /sys/class/gpio/export
>> echo out > /sys/class/gpio/gpio17/direction
>> chown charles /sys/class/gpio/gpio17/value
>>
>> inside pd:
>>
>> [ set 1 (  [ write /sys/class/gpio/gpio17/value cr (
>> |
>> [ textfile ]
>>
>> works.
>>
>>
>> I use it to drive a light system from a track of a audio file containing
>> only square waves at a given frequency (say, cues embedded inside an
>> audio file).
>>
>> I basically snapshot~ and see if it's over or below 0, and turn the gpio
>> on/off on change.
>>
>> I started using pd on the pi three hours ago and have it playing audio and
>> banging the gpio in no time.
>>
>> Thanks to all for this wonderful community.
>>
>> I'm very happy ;).
>>
>>
>> --
>> Charles
>>
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>
>
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