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@sourcelibre.com> wrote: Hi,
2007/6/21, tim info@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
PD-list@iem.at mailing list UNSUBSCRIBE and account-management -> http://lists.puredata.info/ listinfo/pd-list
-- thomas ouellet fredericks, tof@danslchamp.org, montreal, canada _______________________________________________ PD-list@iem.at mailing list UNSUBSCRIBE and account-management -> http://lists.puredata.info/ listinfo/pd-list
'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