Re: About stepper motors controlling (help)

simnav@xxxxxxxxx wrote:
I'm looking for the best way for stepper motor controlling: I tried to
approximate the continuous space versus time curve, calculating the
time intervals where space increase one but it requires square root
and divisions that whould force me to choose a very fast
microcontroller/dsp. I've looked for some commercial controller and
I've seen that all of them have a cycle loop: seems like they don't
control directly space; they instead update the speed at any control
cycle approximating so the speed versus time curve: it is correct ?

Thanks in advance.

Simone Navari.

Have a look at the bottom half of this page:
http://micromouse.cannock.ac.uk/motors/stepper_driving.htm
and also check the Silabs application note:
http://www.silabs.com/public/documents/tpub_doc/anote/Microcontrollers/en/an155.pdf
(sorry if that wraps in your newsreader) Which takes the technique one stage further so that you only need a single table of pre-calculated timer values for any values of acceleration.

Consider also using a timer in your microcontroller as a rate generator to send a pulse train out to the stepper driver at a known frequency. Vary this for the speed. However, you will need either encoder inputs to tell you how far you really moved or some way to count the pulses sent to the motor, assuming no loss of steps.

Pete
.

Relevant Pages

  • About stepper motors controlling (help)
    ... approximate the continuous space versus time curve, ... time intervals where space increase one but it requires square root ... I've seen that all of them have a cycle loop: ... control directly space; they instead update the speed at any control ...
    (comp.arch.embedded)
  • About stepper motors controlling (help)
    ... approximate the continuous space versus time curve, ... time intervals where space increase one but it requires square root ... I've seen that all of them have a cycle loop: ... control directly space; they instead update the speed at any control ...
    (sci.electronics.design)