[PD] arduino+solenoid concert

[Hans-Christoph Steiner]

Most of the problem is likely caused by the USB-serial driver, which  
is optimized for thruput rather than low latency.  It can cause long  
delays.  We have been looking into ways to fix this, but it's not simple

http://arduino.cc/playground/Interfacing/Firmata

You can also read about the design decisions for Firmata, including  
latency and jitter concerns.  For example, an ASCII based protocol  
like SMS will have a large amount of jitter because it sends two  
bytes for small values (<10) and five bytes for large values (>999).

I am working on a Firmata library for Arduino which should make it  
pretty easy to use the Firmata protocol in custom firmwares...  It's  
not quite there yet.  It works for sending input messages now.

.hc

On Jun 22, 2007, at 9:16 AM, Thomas O Fredericks wrote:

> > "So, SMS is signicantly slower because it uses ASCII conversion ?
> > Interesting. Even at high baud rates ?"
>
> SMS is aimed at ease of use and precision. Although I am surprised  
> to ear about SMS's and Pduino's speed problems.
>
> I made an installation with an SSC-32 servo controller controlling  
> 24 servos connected to PD. The SSC-32 is based on the SAME chip as  
> the Arduino and  uses a communication protocol VERY similar to SMS  
> and I never experienced any problems.
>
> Maybe you are not keeping your messages simple enough?
> Or maybe the big difference was that I was using a hardware serial  
> port and not a USB>Serial chip/converter.
>
> Tom
>
>
> On 6/21/07, Alexandre Quessy < listes at sourcelibre.com> wrote:
> Hi,
>
> 2007/6/21, tim <info at timvets.net>:
> >
> >  Roman Haefeli wrote:
> >  On Thu, 2007-06-21 at 09:21 -0400, Alexandre Quessy wrote:
> >
> >  Hi!
> > I don't want to insist... but a task like this would be much easier
> > with the
> > http://www.arduino.cc/playground/Code/SimpleMessageSystem
> > than with something not-as-flexible like Pduino.
> >
> >  I agree to that.
> >  We did something similar a while ago, with realys, shift- 
> registers and 13
> > solenoids.
> >  It was fairly easy to make one firmware for pd communication  
> with SMS as
> > well as shifting code to drive the relays.
> >  More complex passages showed some timing fluctuation, but  
> overall timing
> > was pretty good.
> >  Polyphony was kept at a maximum of 4, above that, things became  
> more
> > unstable.
>
> So, SMS is signicantly slower because it uses ASCII conversion ?
> Interesting. Even at high baud rates ?
>
>
> >  In case you're interested, see
> > www.timvets.net/projects/erkiandtim/poltergeist
> >  We obviously were more inclined to drink beer than to shoot film  
> that
> > night...;)
>
> Error 404 !
>
> a
>
> >
> >  Tim
> >
>
> --
> Alexandre Quessy
> http://alexandre.quessy.net
> http://www.puredata.info/Members/aalex
>
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>
>
> -- 
> thomas ouellet fredericks, tof at danslchamp.org, montreal, canada
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'You people have such restrictive dress for women,’ she said,  
hobbling away in three inch heels and panty hose to finish out  
another pink-collar temp pool day.  - “Hijab Scene #2", by Mohja Kahf


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