Stepper motor wiring help(and a few other small questions from an instructable)

There all about the CNC Project, if you simply go to https://youtube.com/c/thebreadboardca and look at the video list it may be easier to understand as the descriptions are there along with suitable images

btw, the video is almost completed uploading and will be available in a few minutes https://youtu.be/pSJQWe5iGn0

I will post a formal blog entry tomorow with code and everything and embed the video

for now, here is the final code so you can try it and let me know if it works

Enjoy

#include <Stepper.h>


const int stepsPerRevolution = 48;  // change this to fit the number of steps per revolution
// for your motor


// initialize the stepper library on pins 8 through 11:
int motorPinA = 8;                      //Winding A.
int motorPina = 9;                      //Winding a.
int motorPinB = 10;                     //Winding B.
int motorPinb = 11;                     //Winding b.
int rpms = 300;                         // Revolutions per minute  for stepper 300/60 = 5 revs per second = 240 steps per second = about 25 scans per second
Stepper myStepper(stepsPerRevolution, motorPinA, motorPina, motorPinB, motorPinb);


int StepSize = 1;


int LaserState = LOW;                    // The variable that stores the state of the laser beam.
int sensor = 8 ;                         // Change this value to calibrate your harp's sensor
int delaylaser = 3;                     // If you increase this, the laser will be brighter, but the harp will be less fluid
int delaymotor = 3;                     // This variable affects the speed, and fluidity of the harp.

int LaserPin =  7;                       // Tell the arduino that the laser is on pin 7

int notes[] = {0x47, 0x40, 0x71, 0x70, 0x68, 0x66, 0x64, 0x53, 0x61 };
int notesState[] = {0x0, 0x00, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0 };
int arraySize = sizeof( notes )/ sizeof( notes[0]);
int cmd = 0x90;
int VelocityOn = 0x7F;
int VelocityOff = 0x00;


void setup()
{
  pinMode(LaserPin, OUTPUT);            // Setup for laser.
  pinMode(13, OUTPUT);                 // Setup for status led.
  Serial.begin(31250);                 //  Start a serial communication channel for MIDI


  myStepper.setSpeed(rpms);
}


void loop()
{


  // we will do note 0 to keep things consistant at th end of the loop
  //SenseLaser(0)                               // note 1 (Array is zero based)


for (int counter = 0 ; counter < arraySize ; counter++)
{
  myStepper.step(1);                          // Step the stepper ++
  //delay(delaymotor);                          // Small pause, may not be needed ??
  SenseLaser(counter);                        // note counter
}


for (int counter = arraySize-1 ; counter >= 0  ; counter--)
{
  myStepper.step(-1);                          // Step the stepper ++
  //delay(delaymotor);                          // Small pause, may not be needed now
  SenseLaser(counter);                        // note counter
}


  // Back to top.
}


void SenseLaser(int index)
{
  digitalWrite(LaserPin, HIGH);               // Turn on the laser for the 1st beam.
  delay(delaylaser);


  if (analogRead(0) > sensor )
  {
    noteOn(index);
  }
  else if (analogRead(0) < sensor )            // If the sensor does not get a signal:
  {
    noteOff(index);
  }
  digitalWrite(LaserPin, LOW);                // Turn off the Laser.
}


void noteOn( int pitchindex)     // Function to play the notes
{


  if (  notesState[pitchindex] == 0) // If the sensor gets a signal, and the not is not playing:
  {
    Serial.write(cmd);
    Serial.write(notes[pitchindex]);
    Serial.write(VelocityOn);
    notesState[pitchindex]++;                          // Change the status variable to one.
    digitalWrite(13, HIGH);       // Switch on status led.
  }
}
void noteOff( int pitchindex)     // Function to play the notes
{
  if (  notesState[pitchindex] > 0) // If the sensor does not get a signal, and the not is playing:
  {
  Serial.write(cmd);
  Serial.write(notes[pitchindex]);
  Serial.write(VelocityOff);
  notesState[pitchindex] = 0;                        // Change the status variable to 0.
  digitalWrite(13, LOW);       // Switch off status led.
  }
}

Robert Peter Oakes

The Code runs, but I'm having the same issue, the stepper is stepping, but with long pauses in between steps.

try putting this parameter to a smaller value like 50 or something

int rpms = 300;

this may see if the stepper is simply not fast enough, I dont have the chip or a stepper like yours to try so cant verify that

I have plenty of large steppers but again, not he same as yours

If you slow down the steps using the above parameter enough, you could place LEDs on the output of the arduino and ensure the sequence ir sight, I did that here and it looks good to me, You can also check the stepper connection from the chip to stepper with a DMM and verify the voltages are changing are of a correct value.  If you have two DMMs then you can verify the actual sequence is correct to the stepper windngs and that the voltages are reversing etc.

outside of that, im not sure what else I can do as you have verified you wiring, the code now is correct as best I can see so unless your chip is getting really hot for some reason, it should be working

Regards

Peter

Ah, one thing I forgot to also mention and it may be important. ( I am so used to them being there I completly missed the fact they were not there)

Decoupling capacitors on the supply rails near the chip for both the +5V and the 12V.

I dont see any on your board and there essential for reliable operation

looking at this circuit from TI it clearly shows them, and the value required

I'll test that out when I get home, i think i have two .1μF at my bench from something else, so that's convenient.  If it helps, here is the datasheet for my stepper  http://cdn.sparkfun.com/datasheets/Robotics/ST-PM35-15-11C.pdf .  What do the capacitors do in this case, I mean I know what capacitors do in general, but why would they make a difference here?

Robert Peter Oakes

The capacitors I have at home are ceramic caps.  Would these work? HQ 1uF 50V Aluminum Radial Electrolytic Decoupling Capacitors Pack of 20 | eBay

Robert Peter Oakes

Those should work for the 1μF caps, but I can't find any .1μF decoupling caps, could you link me some?

yup, should be good

try finding some 100nF instead, you should find thouse and they will do instead of the 0.1uF

Robert Peter Oakes
I can't find any of those either, maybe i'm being too specific.  can u send me a link?