[PD-ot] Raspberry Pi (still is: openstomp ... PD pedal?)

[Michael Zacherl]

On 23.3.2012, at 22:29 , dreamer wrote:

> On the RaspberryPi website the question about the absence of audio-input was answered recently:
> 
> There are no inbuilt Audio ADC’s so there would be a cost adder – everyone was sat on my head to get costs down. They can be easily added via the GPIO.
> 
> So, still a possibility in an embedded openstomp-ish device.

uh-oh ...just from my guts I'm not sure if this is efficient and feasible.
GPIO is a bunch of headers to connect digital signals to and from the outer world to the RPi.
AFAIK all what be can done so far is connecting something via I2C or SPI or set individual pins on and off on a lower level.
(SPI and I2C libraries exist, if I'm not mistaken)
So you need to create audio hardware, the interface to the RPI and write a driver (!) which connects to ALSA and/or JACK.
Given that even a more expensive USB audio dongle like the Griffin iMic costs just under €40 I'm note sure if that's worth the hassle.
Just my 2c - Michael.


> On Sun, Mar 4, 2012 at 6:26 PM, dreamer <dreamer at puikheid.nl> wrote:
> An arm-based device I would like to have pd on is the Pandora, based
> on the OMAP3530.
> Which has audio-in/out and gpio on a single plug.
> 
> Combining that with a stompbox that holds, for instance, an msp430
> (launchpad, by ti) with an lcd-screen and some nobs would make for a
> very nice interface :)
> 
> Still looking in to compiling for their OS.
> The pandora is then again a very small niche, hence I was reflecting
> on the current interest towards the RasPi.
> However I didn't realize this device doesn't have line-in, so that
> indeed is a little discouraging.
> 
> Alexander
> 
> 
> 
> On Sun, Mar 4, 2012 at 6:15 PM, Ed Kelly <morph_2016 at yahoo.co.uk> wrote:
>> Hmm. Doesn't seem to have an audio input though, so perhaps it'll work for a
>> synthesizer but not for a "stompbox" straight away. The site recommends a
>> "USB microphone" for audio in, so that's not encouraging...
>> Ed
>> 
>> 
>>> So what about a Raspberry Pi  inside a stompbox that runs pd?
>>> But could the arm11 in that thing handle awesum (sic) audio processing? ;)
>> 
>> Well the Raspberry Pi is based on an ARM chip. Does anyone know how these
>> chips compare when running RJDJ or libPD applications?
>> Perhaps this is a possibility, without too much modification of libPD or
>> even RJDJ.
>> ...but someone would need to write a host for the Raspberry Pi.
>> 
>> 
>>> What do you need by "writing a host for Pd"? Something like a very simple
>>> OS?
>> 
>> Er..well I can see they run Linux, so I think I was mistaken. My head was in
>> the world of BASIC - nostalgia gets in the way of the facts!
>> Of course, Pd would need to be compiled for the hardware.
>> 
>> I think we need to wait until one of us gets one and tries it out before we
>> find out what they're capable of. I've expressed interest, but they're
>> massively oversubscribed.
>> 
>> 
>> 
>>> I bought mine yesterday, and should receive it in about a week. The first
>>> thing I'll do is try to install Pd.
>> 
>> 
>> 
>> On the other hand, the idea of a dedicated PDOS isn't a bad idea...
>> Ed
>> 
>> 
>>> Yes, how hard would it be to have this?
>> Well, it could be a highly stripped-down version of Linux. I don't think
>> anyone has the time to write an OS, so I was being mischievous in suggesting
>> this. I am having some funny ideas today...
>> Ed
>> 
>> Pierre.
>> 
>> 
>> Even if it was just the PD core, it would enhance the educational scope of
>> the Raspberry Pi - which is the whole point of this single-board computer (I
>> learned my first programming on a Sinclair ZX Spectrum in the 1980s).
>> 
>> I never thought I would see the day when the BBC Microcomputer would rule
>> the world in telecommunications, but ARM chips and the ARM RISC instruction
>> set are running  every smartphone on the planet right now (correct me if I'm
>> wrong :) and some of these smartphones run RJDJ and libPD really well.
>> 
>> Dataflow music programming in schools. Maybe...
>> 
>> Ed


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