Stepper motor only goes in 1 direction

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Phil_Rounds
 
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Stepper motor only goes in 1 direction

Post by Phil_Rounds »

I have a stepper motor of unknown origin which I can only get to go in one direction using my MotorShield V2.
I the motor diagram has B+, B- and A+, A- identified, and I have them connected to M1/M2 as A+/- gets connected to M1 according to the polarity when I run a dc motor on M1 (+ = outside, - = inside). Same for B+/- and M2.

I'm using code I've used for years,



Adafruit_MotorShield Shield = Adafruit_MotorShield();
Adafruit_StepperMotor *myMotor = Shield.getStepper(24,1); // (it's a cheap,mini motor, 24 steps per on revolultion


void Up(int Steps)
{
Serial.print("Up: "); Serial.println(Steps);
myMotor->step(Steps, FORWARD, SINGLE);
}
void Down(int Steps)
{Serial.print("Down: "); Serial.println(Steps);
myMotor->step(Steps, BACKWARD, SINGLE);
}

Both Up( 40 ) and Down( 40 ) result in about 7/ 8 of a counter clockwise revolution.

Any ideas? (other than buy from a legit source rather than the first thing that showed up on Amazon? It's really the assembly it came in that I was interested in rather than the motor, I just need the motor to work to test the assembly)

Thanks

Phil

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dastels
 
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Re: Stepper motor only goes in 1 direction

Post by dastels »

In the assembly you mention... is it meant to go in both directions?

Dave

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adafruit_support_bill
 
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Re: Stepper motor only goes in 1 direction

Post by adafruit_support_bill »

Some motors tend to run slightly better in one direction than the other. But if it is not running at all, it could be a motor compatibility problem.

Measure the resistance between one pair of the motor leads. If it is less than about 10 ohms, there is a good possibility that it is not compatible with the drivers on the shield.

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Phil_Rounds
 
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Re: Stepper motor only goes in 1 direction

Post by Phil_Rounds »

It moves when I tell it to go Up(40) and when I tell it to go Down(40), but it goes in the same direction, even though I specify FORWARD / REVERSE in the Up / Down commands

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adafruit_support_bill
 
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Re: Stepper motor only goes in 1 direction

Post by adafruit_support_bill »

What is the resistance between the motor leads?

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Phil_Rounds
 
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Re: Stepper motor only goes in 1 direction

Post by Phil_Rounds »

Bill - Sorry for the delay, but I was away from the lab yesterday afternoon. You were right-ish, the resistance on A+/A- was 60ohms , but B+/B- was open, so I'm guessing the motor was just shot

Thanks,

Phiul

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adafruit_support_bill
 
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Re: Stepper motor only goes in 1 direction

Post by adafruit_support_bill »

With one winding open, I'm surprised that it turns at all. Normally I'd expect it to just vibrate back & forth. Could be that there is enough inertia in the drivetrain to skip over the 'dead' phases.

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