TUTORIAL: how to control a BIpolar stepper motor

ok from now on I'll write in english, I have to learn it.

In this tutorial I will show you how to control a stepper motor with FOUR control wires and a L293D IC. You can use everything you want in order to generate control signals. In this tutorial I used an Arduino board, but a PIC is also ok.

Why "FOUR" control wires? because everyone who writes a tutorial  or something else about bipolar stepper motors wants to control them with only TWO wires and a lot of components (NPN transistors, resistors ecc ecc). But controlling a L293D with 4 wires is simpler!

ok, let's see the circuit:




How does the L293D work?


That's simple: you send a signal on the "inputX" and then the IC "opens" the port "outputX" for the current passing.
You can also enable or disable a particular input-output "phase" (pin 1 and 9), but in this tutorial they are always enabled.

This is the result:


and this is a (very) simple sketch of Arduino programming:

//declaration of PINS that connected the wire to motor
int nero = 13;
int marrone = 12;
int arancio = 11;
int giallo = 10;

//this is the time to wait in every single step
int delayTime = 100;

//set the pin for OUTPUT
void setup() {
  pinMode(nero, OUTPUT);
  pinMode(marrone, OUTPUT);
  pinMode(giallo, OUTPUT);
  pinMode(arancio, OUTPUT);
}

void loop() {
  forward(13);
  delay(500);
  backward(13);
}

void forward(int steps){
  for(int i=0;i<steps;i++){
// in every phase 2 wires is up and 2 is down
    digitalWrite(nero, LOW);
    digitalWrite(marrone, HIGH);
    digitalWrite(arancio, HIGH);
    digitalWrite(giallo, LOW);
    delay(delayTime);
 
    digitalWrite(nero, LOW);
    digitalWrite(marrone, HIGH);
    digitalWrite(arancio, LOW);
    digitalWrite(giallo, HIGH);
    delay(delayTime);
 
    digitalWrite(nero, HIGH);
    digitalWrite(marrone, LOW);
    digitalWrite(arancio, LOW);
    digitalWrite(giallo, HIGH);
    delay(delayTime);
 
    digitalWrite(nero, HIGH);
    digitalWrite(marrone, LOW);
    digitalWrite(arancio, HIGH);
    digitalWrite(giallo, LOW);
    delay(delayTime);}
}

void backward (int steps){
  for(int i=0;i<steps;i++){
    digitalWrite(nero, HIGH);
    digitalWrite(marrone, LOW);
    digitalWrite(arancio, HIGH);
    digitalWrite(giallo, LOW);
    delay(delayTime);
 
    digitalWrite(nero, HIGH);
    digitalWrite(marrone, LOW);
    digitalWrite(arancio, LOW);
    digitalWrite(giallo, HIGH);
    delay(delayTime);
 
     digitalWrite(nero, LOW);
     digitalWrite(marrone, HIGH);
     digitalWrite(arancio, LOW);
     digitalWrite(giallo, HIGH);
     delay(delayTime);
 
     digitalWrite(nero, LOW);
     digitalWrite(marrone, HIGH);
     digitalWrite(arancio, HIGH);
     digitalWrite(giallo, LOW);
     delay(delayTime);
  }

}


PS
this page: http://www.arduino.cc/en/Tutorial/StepperBipolar  is for UNIPOLAR stepper motor!