Thanks Thomas – damn, I thought all pins were 5v – I saw that there was a power pin at that level, and assumed the others were too.

So when you say "PWM is easily configured" - do you mean that it is some setting that I adjust on the Pi itself, and then getting a variable voltage is as simple as sending a value between 1 and 1023 from Pd to the Pi?

Or do I have to do some programming within Pd to do the actual PWM? If this is the case – that's exactly what I need help with, not sure how to do that.

Thanks!! Dan -- Dan Nigrin / Defective Records / http://defectiverecords.com http://defectiverecords.com/ CycliC, M185 & Klee Sequencers / MC-4 & MC-202 Hack / Audio Plugin Player / General MIDI Player / Major Malfunction Jack OS X / http://jackosx.com http://jackosx.com/

From: Thomas HOCEDEZ thomas.hocedez@free.fr Date: Wednesday, July 24, 2013 5:34 AM To: J Oliver jaime.oliver2@gmail.com Cc: PD List pd-list@iem.at, Daniel Nigrin dan@defectiverecords.com Subject: Re: [PD] gpio on the raspberry pi from within pd ?

Hi !

PWM on RPi is easyli configured, with a value from 1 to 1023. Be careful only some GPIO are PWM : https://www.modmypi.com/blog/raspberry-pi-gpio-en-franais

The voltage output will be 3V3 @100%, I have to check this, but pretty sure.

REgards.

¤º°¯ ¯°²º¤æ=¬« Thomas HOCEDEZ »¬=椺²°¯ ¯°º www.asthrolab.fr

De: "J Oliver" jaime.oliver2@gmail.com À: "Dan Nigrin" dan@defectiverecords.com Cc: "PD List" pd-list@iem.at Envoyé: Mercredi 24 Juillet 2013 11:13:10 Objet: Re: [PD] gpio on the raspberry pi from within pd ?

Hi Dan,

I am Cc'ing the list, which is really your best resource. I haven't output variable voltages from the pi, but I am sure a lot of people have experience with this...

best,

J

On Jul 24, 2013, at 4:39 AM, Dan Nigrin wrote:

...

Hi Jaime,

Saw this post of yours from back in April re: GPIO access from within Pd on the Raspberry Pi:

http://lists.puredata.info/pipermail/pd-list/2013-04/102172.html

I'm a total Pi newbie – I don't even own one yet. I'm considering a project with it though, where I would like to use Pd to generate some audio, and to output it to another device (a Mutable Instruments Shruthi synth filter board). However, I also need to generate control voltages that need to get sent to the filter board, to control its various parameters (e.g. cutoff, resonance, etc...). I also need to send +5v and ground to the filter board.

So from your post, it seems quite straightforward to be able to access the GPIO pins from within Pd. But I need to be able to create variable voltages (between 0 and 5v) on those pins. In the post above, you mentioned that you send a float to the gpio object to write a value to the pin - would sending a 0.5 for example give me 2.5v on the pin? Or is it only on/off (0 or 5v)? If the former, I'm all set! If the latter, I'll need to figure out how to simulate a reduced voltage at the pin (likely using PWM or something – but I'm not really sure how I would do that…)

Any help greatly appreciated!

Best, Dan -- Dan Nigrin / Defective Records / http://defectiverecords.com http://defectiverecords.com/ CycliC, M185 & Klee Sequencers / MC-4 & MC-202 Hack / Audio Plugin Player / General MIDI Player / Major Malfunction Jack OS X / http://jackosx.com http://jackosx.com/

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