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Reconn’s World has an interesting article with sample code of a stepper motor speed controller.
“While the stepper motor could be completely computer-controlled, I’d like to be able to change the speed of the motor by turning a dial. for this i’m using a linear potentiometer from radioshack (10kohm, RadioShack #271-1715.) I’ll read the voltage off of the middle pin — turning the potentiometer will cause this middle-pin voltage to swing from ground to +Vcc (5v in my case). I will read this voltage in via the PIC’s analog-to-digital converter and control the motor’s speed accordingly.”
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November 3rd, 2006
Not to be a smartypants, but you’ve connected a potentiometer to program a motor controller to vary the speed of a stepping motor. Wouldn’t it be simpler to run a DC motor with varying voltage?
That said, I can think of a dozen reasons to do this, not the least of which being “because I can”. Good job!
November 3rd, 2006
Hehe,
the “because i can” excuse is certainly a good one :). and yes you could vary the voltage of a dc motor, the problem (depending on your goal) is that you have no idea what speed the motor is running. with a stepper motor (when it’s not under heavy load and slipping) you know the speed it’s rotating depending on how quickly you pulse it. in my application i want to have a good idea of it’s speed w/out building a feedback circuit (though i did use a mechanical switch to verify operation)
check out the verfication bit at http://www.reconnsworld.com/plog/archives/7-PIC-Code,-Verified.html#extended