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

[Julian Brooks]

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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