On 11 June 2010 14:53, Jeff Epler <[email protected]> wrote:

Ignore the code, I need to take a course in remedial-level git and dif.

> I am still concerned about 'dir'.  I see that if angle is 90 that
> negating value or inverting dir do the same thing, but for other values
> of angle this isn't true.  For instance, if 'angle' is 60 and you try to
> invert the rotational direction by having a negative 'value' and not
> changing 'dir' then you'll get an effective theta of -120 when the
> desired is -60.

I agree, I can't see it any other way.

But... reversing the polarity of the motor terminals of a permanent
magnet motor always reverses the motor, as far as I know. Sending a
negated voltage pattern to the 3-phase PWM produces the inverse
gate-drive voltages, which I think is exactly the same as a polarity
switch.

I am pretty sure that I prefer the approach of swapping the lead angle
though, and intend to make that change if I ever trust myself near a
computer again after this diff-posting debacle.

However, I don't particularly like the idea of a "Scale" pin as there
is already one on the 3ppwmgen function, and nesting scales sounds
like a lot of scope for confusion.
Perhaps rename it as a "reverse" pin?

-- 
atp

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