Re: ATM steppers & microcontrollers

[Mel Bartels <mbartels@efn.org>]

The pulse width modulation pulses are wide or long enough that you can
take their time spent while logical high to use in voltage or current
calculations.  The on/off times of the opto-isolators and transistors as
well as latency in the parallel port come into play with PWM values of
'1' or '2', in otherwords, only on very very short PWMs.

I explain in detail on my computerized dob webpage, but basically if 'A'
winding is at a current/voltage value of 10, and 'B' winding is at '5',
then the rotor will feel 10^2 attraction to 'A' and 5^2 attraction to
'B', resulting in a positioning of the rotor 4 times closer to 'A' than
'B'.  Running the rotor through angles and calculating their sin/cos
automatically generates the proper current/voltage ratios for 'A' and
'B'.
--
Clear skies, Mel Bartels    Programmer/Analyst, amateur astronomer
Eugene, Oregon, USA         homepage: http://www.efn.org/~mbartels
mailto:mbartels@efn.org     atm, atm-digest list-owner
Motorize A Dob: http://zebu.uoregon.edu/~mbartels/altaz/altaz.html