On Mon, 5 Aug 2002, Francisco Ares wrote:

>Hi all PIClisters.
>
>Can someone point me to an algorithim to do accelaration for a stepper
>motor controller?
>
>My controller uses one timer overflow ISR to switch the phases of the
>motor, so the speed is calculated through the period register of this timer.
>
>I need to calculate different values for the period register for a
>constant (or close to constant) acceleration, preferably "on-the-fly",
>inside the same ISR.
>
>My first atempts resulted in that the final speed was never reached
>because of accumulating errors in calculations.

For each 'step' of acceleration you compute Time1 = Time0 - dt and set the
timer to that. dt is set previously = (Starttime - Fasttime)/Numsteps,
where Numsteps is the number of intermediate speeds you need and Starttime
a timer value that corresponds to a minimum safe starting speed. When
Time0 == Fasttime you have arrived to max speed.

Peter

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