Fez Panda II - How fast are the output pins?

Discussion in 'The Projects Forum' started by squatchy, Nov 27, 2012.

  1. squatchy

    Thread Starter Member

    Nov 21, 2012
    43
    0
    How quickly can the values on the general purpose pins of a microcontroller be updated? Specifically, if I buy a Fez Panda II and try to write software that will write a new 3-bit character (to 3 output pins) 500 times per second, is that realistic? The data won't be simple oscillations or PWM.... it will be updated at regular intervals, with generated data like this:

    010
    000
    110
    000
    110
    100
    110
    000
    110
    100
    010

    I don't want to buy it and find out it can only do this 4 times per second. :/

    Thanks for your time.
     
  2. Papabravo

    Expert

    Feb 24, 2006
    10,148
    1,791
    A 2 millisecond period does not seem unreasonable for any run of the mill microcontroller. It would help if you could provide a link to the candidate units since I've never heard of them and am not familiar with who makes it and what speed it might be running at.
     
  3. squatchy

    Thread Starter Member

    Nov 21, 2012
    43
    0
    Here's the board:
    http://www.ghielectronics.com/downloads/FEZ/Panda_II/FEZ_Panda_II_UserManual.pdf

    I can't find any info on I/O speeds though. And just to clarify, what I need is an I/O system which can output/update 3 pins at a rate of 25,500/second or close, which means it could present a new 3-bit value to the pins in about .04ms, every .04ms. Is that a ridiculous expectation?
     
  4. squatchy

    Thread Starter Member

    Nov 21, 2012
    43
    0
    It says 54X digital I/O speed but I don't know what that means or how that converts to hertz.
     
  5. Papabravo

    Expert

    Feb 24, 2006
    10,148
    1,791
    It is an ARM Processor running at 72 MHz. I would expect that, programmed in assembly language, it could easily update an I/O register every 40 microseconds (= 0.04 milliseconds) and still spend most of it's time spinning.

    It is more complicated than your run of the mill 8-bit part so you should be prepared for a more substantial learning curve. Getting the freeware tools such a YAGARTO up and running is challenging.

    The 54X is not directly convertible into engineering units. It is relative to something else which is not identified.
     
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