Stepper motor won't turn, just vibrates

Question

I'm using 2 x 1.8-Degree Nema 14, 35 BYGHW Stepper Motors with a DRV8825 Stepper Motor.

I have tried all 24 combinations of wiring the damn 4 wires but it won't work. I am using a 9v battery as the motor power source, which is fine.

It sometimes turns when I have 3 wires connected??

I can guarantee the wiring is correct, and this is the sketch.

Here is the code, which I am almost certain is correct too, I just started this project and I can't even get a damn motor to work!

/* stepper motor control code for DRV8825
 * 
*/

// define pin used
const int stepPin = 9;
const int dirPin = 8;

void setup() {
  // set the two pins as outputs
  pinMode(stepPin,OUTPUT);
  pinMode(dirPin,OUTPUT);

}

void loop() {
  digitalWrite(dirPin,HIGH); //Enables the motor to move in a perticular direction
  // for one full rotation required 200 pulses
  for(int x = 0; x < 200; x++){
    digitalWrite(stepPin,HIGH);
    delayMicroseconds(500);
    digitalWrite(stepPin,LOW);
    delayMicroseconds(500);
 }
 delay(1000); // delay for one second


  digitalWrite(dirPin,HIGH); //Enables the motor to move in a opposite direction
  // for three full rotation required 600 pulses
  for(int x = 0; x < 600; x++){
    digitalWrite(stepPin,HIGH);
    delayMicroseconds(500);
    digitalWrite(stepPin,LOW);
    delayMicroseconds(500);
  }
  delay(1000); // delay for one second
}

Answer 1

There was no need to try 24 wiring combinations.

Your schematic shows that you have a two-coil motor. You identify the two coils with your multimeter and connect one coil to A1 - A2 and the other to B1 - B2. The motor should now run if you are using full-step mode. If using half-step mode (where more than one coil is on at time) you may need to reverse one of the coils.

A 9 V battery may not be adequate. Measure the battery voltage while trying to run the motor.

You can also increase the step delays by a factor of 100 and see if the motor turns slowly and whether or not you can feel any torque.

For further help please edit your question and add a link to the motor datasheet.

Answer 2

1. 9V batteries are very weak. When I was a kid, they were sometimes called transistor batteries, since that is all they were good for, powering low-power transistor radios.

2. Is the enable_n pin low by default? You may need to drive it low.

3. Use full step mode until you get it to work.

4. Try longer delays. If you want to run the motor fast, you need to accelerate gradually. There are drivers to help you for some MCUs.

Answer 3

If I had to guess and the motor is really rated at 1.2 Amps, you are fighting a losing battle! There's no way in the world you can suck 1 Amp out of a 9 volter! You basically need to start with a beefier power supply, say 3 Amps or so and you possibly may have to put transistors between the motor and the controller.

Answer 4

Two things: Steppers have a lot of mass in the rotor and thus high inertia. Your 1-millisecond initial move may cause it to bounce between one step behind / one step ahead, which would be similar to the buzzing and vibrating you see. You need to allow it time to spin-up or by having longer delays initially. You can try one of the microstepping modes of the 8825 (the Mx inputs) this will allow a more gradual move between poles.

The 9v battery might be too weak. As a rule of thumb, to move fast, you want high voltage, for greater torque, you want high amperage.

I can recommend a library called "AccelStepper" for controlling if you aren't determined on writing your own. It's always fun and full of important learnings to write it yourself.

Answer 5

I'm using a 28BYJ stepper which had a similar problem initially. I corrected it by increasing the delay time from 500s to 2000ms and decreasing the rpm from 100 to 20.