MSP>Arduino Latency test results


    Sep 12 2010 | 11:02 am
    hello,
    I ran a latency test today using arduino & max msp , I used a maxuino patch to communicate between the two.
    what i wanted to find out was : How long does it take to send a signal from the PC computer out to arduino and back into the computer? I sent a signal along the following path : max/msp > serial/usb > arduino digital out >arduino digital in> usb/serial>max msp.
    i used a timer module inside max msp to take the readings.
    results:
    Each time i send a test signal/bang out of max/msp I get a range of latencies for its return back in.
    it is not a constant figure, i have readings between 3 ms > 19ms each time i send a single bang.
    just thought id post this. maybe there is a way to tighten this up ?
    peace : )

    • Sep 12 2010 | 8:29 pm
      just wanted to say thanks for this
      it's good to know these things; it would be important to know your OS etc
      Brendan
    • Sep 13 2010 | 8:22 am
      As far as I can see, maxuino uses JavaScript (which is 200 slower than everything else in the world...) to process the i/o. I think it would be a better idea to do benchmarks using only serial and a couple of other standard Max objects.
      And I'm not sure neither that firmata is optimized for a loopback.
      Last time I tried, a speed of 115200 bps worked quite well between Max and an Arduino but Maxuino uses a bit rate of 57600.
      p
    • Sep 30 2010 | 5:17 pm
      hi Patrick : ) wow, thanks for the info. I was about to run some tests again very soon on the arduino. I was just searching for the preference page you mention so to alter the latency and 'bps rate' ..I cant find it now.: ? This is how i found out you posted here , as i saw your message on a google search, lol :) ( i haven't had an email notification.)
      I shall have a go with the serial object too, I haven't used that yet by itself as you say and see how it performs.
      there are other micro boards i might try like the 'make controller'
      this looks real nice. http://makezine.com/controller/
      i was just after the lowest latency possible (p.s I am on xp , but have an ubuntu machine too ,that might help)
      peace: )
    • Sep 30 2010 | 5:21 pm
      hello to everyone reading : just to clarify, i am on xp and i am sure as patrick says, the serial object by itself might bring better results as the 'bps rate' can be raised and i am sure i saw a latency page the other day somewhere?( which inspired me to try again, but ive lost it, darn it. i'll report back soon,
    • Oct 01 2010 | 7:00 am
      There is no preference page to set the bit per second rate. It's coded in the arduino and in trhe patch.
      On the arduino side, look for a
      Serial.begin(blah)
      in the setup() procedure, where blah is the bps.
      On the Max side, the bps is an argument of the serial object. Both bps must match.
      But I think the bottleneck here the polling speed.
      The make controller is nice too, more plug&play than the arduino and more powerfull (although I had too many small problems with their v2 compared to v1). I don't know its latency, but it's fast enough for my needs!
      Why do you worry so much about latency?
      p