Motor Shield V2 Can't get any power to the motor ports

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MikeCooper
 
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Motor Shield V2 Can't get any power to the motor ports

Post by MikeCooper »

I am trying to set up my first stepper motor and I can't seem to get any signal, power to the motor ports. You can tell in the pic but the green light is on. I have tried the dc motor test, the stepper, both ports 1/2 and 3/4. The motor is a 6 wire and the diagram is attached as an image. I am using a Due and powering the shield by an external 12v power source. I had the shield working with a servo about a year ago and haven't touched it since then. I have never tried any of the motor ports, only the servo. I am using the example code for the stepper test and it is attached below.

I would really appreciate some guidance.

Thank you

Mike
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Code: Select all

/* 
This is a test sketch for the Adafruit assembled Motor Shield for Arduino v2
It won't work with v1.x motor shields! Only for the v2's with built in PWM
control

For use with the Adafruit Motor Shield v2 
---->	http://www.adafruit.com/products/1438
*/


#include <Wire.h>
#include <Adafruit_MotorShield.h>
#include "utility/Adafruit_MS_PWMServoDriver.h"

// Create the motor shield object with the default I2C address
Adafruit_MotorShield AFMS = Adafruit_MotorShield(); 
// Or, create it with a different I2C address (say for stacking)
// Adafruit_MotorShield AFMS = Adafruit_MotorShield(0x61); 

// Connect a stepper motor with 200 steps per revolution (1.8 degree)
// to motor port #2 (M3 and M4)
Adafruit_StepperMotor *myMotor = AFMS.getStepper(200, 1);


void setup() {
  Serial.begin(9600);           // set up Serial library at 9600 bps
  Serial.println("Stepper test!");

  AFMS.begin();  // create with the default frequency 1.6KHz
  //AFMS.begin(1000);  // OR with a different frequency, say 1KHz
  
  myMotor->setSpeed(10);  // 10 rpm   
}

void loop() {
  Serial.println("Single coil steps");
  myMotor->step(100, FORWARD, SINGLE); 
  myMotor->step(100, BACKWARD, SINGLE); 

  Serial.println("Double coil steps");
  myMotor->step(100, FORWARD, DOUBLE); 
  myMotor->step(100, BACKWARD, DOUBLE);
  
  Serial.println("Interleave coil steps");
  myMotor->step(100, FORWARD, INTERLEAVE); 
  myMotor->step(100, BACKWARD, INTERLEAVE); 
  
  Serial.println("Microstep steps");
  myMotor->step(50, FORWARD, MICROSTEP); 
  myMotor->step(50, BACKWARD, MICROSTEP);
}
Last edited by adafruit_support_bill on Wed Dec 06, 2017 11:35 am, edited 1 time in total.
Reason: Please use [code] tags when submitting code to the forums

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adafruit_support_bill
 
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Re: Motor Shield V2 Can't get any power to the motor ports

Post by adafruit_support_bill »

Please post a link to the specs for the motor you are using.
We need to know the electrical specs.

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MikeCooper
 
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Re: Motor Shield V2 Can't get any power to the motor ports

Post by MikeCooper »

And I thought I had everything needed :)

Step angel (°):1.8 Motor Length L(mm):48 Rate Voltage (V):12 Rate Current (A):0.4 Phase Resistance (?):30 Phase Inductance (mH):28 Holding Torque (oz.in):75 Lead Wire (NO.):6 Rotor Inertia (g.cm2):68 Detent Torque (kg.cm):0.28 Motor Weight (kg):0.34

https://www.amazon.ca/gp/product/B00NGF ... UTF8&psc=1

Hope this is what you need.

Thank you for the quick reply.

Mike

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adafruit_support_bill
 
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Re: Motor Shield V2 Can't get any power to the motor ports

Post by adafruit_support_bill »

Do you have a multimeter? We have seen several motors sold through Amazon that had specs that were drastically different from what was advertised. In particular, I'd like to confirm the phase resistance. Measure the resistance between the red & blue leads and make sure that it is close to 30 ohms. Then do the same for the black and green leads.

Also, for a 6-wire motor, for best performance you should leave the center-tap wires (yellow and white) un-connected. This will operate the motor in bipolar mode instead of unipolar mode.

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MikeCooper
 
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Re: Motor Shield V2 Can't get any power to the motor ports

Post by MikeCooper »

Red -> Blue = 11.8 ohms
Green -> Black = 11.8 ohms

I tried pulling the yellow and white with no luck earlier.

Thank you

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adafruit_support_bill
 
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Re: Motor Shield V2 Can't get any power to the motor ports

Post by adafruit_support_bill »

So then, the resistance between say red & white or blue & white is around 6 ohms?

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MikeCooper
 
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Re: Motor Shield V2 Can't get any power to the motor ports

Post by MikeCooper »

6.2

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adafruit_support_bill
 
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Re: Motor Shield V2 Can't get any power to the motor ports

Post by adafruit_support_bill »

That's what I was afraid of. Somebody at Amazon needs to get themselves a multimeter.

At 12v, the current through 30 ohm coil would be about 0.4 amps - as advertised. That is well within the capabilities of the shield.
With an 11.8 ohm coil, the current would be a little over 1A. Substantially higher, but still within the 1.2A rating of the shield.
But wired in unipolar configuration, the bridge chips on the shield are going to see closer to a 6 ohm load which will pull about 2A.

The "(?):30" guesstimate was probably based on a simple application of Ohm's Law to the manufacturer's recommended voltage and current ratings. Unfortunately, these specs don't always mean what it looks like they mean. You really need to know the phase resistance. For more information on matching drivers and motors see: https://learn.adafruit.com/all-about-st ... he-stepper

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MikeCooper
 
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Re: Motor Shield V2 Can't get any power to the motor ports

Post by MikeCooper »

Thank you for your help. I will be returning this stepper.

Do you think I killed the shield?

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adafruit_support_bill
 
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Re: Motor Shield V2 Can't get any power to the motor ports

Post by adafruit_support_bill »

The stepper should work with the shield in bipolar configuration (white & yellow disconnected). But a unipolar configuration would cause an overload. If it does not work after disconnecting the white and yellow, then there is a good chance that the bridges are fried.

If this was purchased via Amazon, I would take it up with them since the advertised motor specs were wrong.. Otherwise, if you contact [email protected] with a link to this thread we can offer you a discount on a replacement.

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MikeCooper
 
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Re: Motor Shield V2 Can't get any power to the motor ports

Post by MikeCooper »

Thank you so much. Excellent service here at adafruit.

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