G'day Steve.

That's a good start but the main drama is i would like to avoid a
look-up-table if at all possible for loading PR. Feeding PR sequential
values will not give a corresponding linear relationship between stepper
speed and PR2. I would love to know a way to use a single number to derive
the PR value without resorting to really complex maths. But maybe there is
no alternative?

Rgds,

Kresho Sprem

> -----Original Message-----
> [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of stesquib@MINES.EDU
> Sent: Saturday, 29 November 2003 5:40 PM
> Check out the timer 2 module. Just set the prescaller and
> postscaller then load
> the desired period (some scaled value) into the PR2 register.
>
> EG:  8 MHz clock: 500ns per cycle.
>      1/(1000 * 500E-9)  (1000  is the max number of interrupts per second)
>      = 2000             (we need and interrupt every 2000 cycles)
>      2000 / 256 ~ 7.8   (atleast 7.8 is needed to obtain
> interrupts at 1kHz)
>      So round up to 8.
>      set some combination of prescale and postscale who's product
> equals 8.
>      The period between interrupts is 500ns * 8 * PR2.
>      T = 0 to 1.024 ms
>
> I'm a big fan of the timer 2 module. All timers should have a
> period register :)
>
> Hope this helps,
> Steve
>

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