ULN2003 Stepper Motor Driver Board

Schematics

Steppers required a power supply of 3V, 5V or more. External power supply should be preferred especially if the motor requires more than 5V. In this case, the stepper can be powered with the pin 5V of the board and the Arduino can be powered via the USB cable.

Code

To control a unipolar motor we used a 8-step sequence. The stepper 28BYJ-48 describe a rotation in 2048 steps.

#define IN1  11
#define IN2  10
#define IN3  9
#define IN4  8
int Steps = 0;
int Direction = 0;
int number_steps=512;//= 2048/4
void setup()
{
Serial.begin(9600);
pinMode(IN1, OUTPUT); 
pinMode(IN2, OUTPUT); 
pinMode(IN3, OUTPUT); 
pinMode(IN4, OUTPUT); 
// delay(1000);
}
void loop()
{
//1 rotation counter clockwise
stepper(number_steps);
delay(1000);
//1 rotation clockwise
stepper(-number_steps);
delay(1000);
//Keep track of step number
for(int thisStep=0;thisStep<number_steps;thisStep++){
stepper(1);
}
delay(1000);
for(int thisStep=number_steps;thisStep>0;thisStep--){
stepper(-1);
}
delay(1000);
}
void stepper(double nbStep){
if(nbStep>=0){
Direction=1;
}else{
Direction=0;
nbStep=-nbStep;
}
for (int x=0;x<nbStep*8;x++){
switch(Steps){
case 0:
digitalWrite(IN1, LOW); 
digitalWrite(IN2, LOW);
digitalWrite(IN3, LOW);
digitalWrite(IN4, HIGH);
break; 
case 1:
digitalWrite(IN1, LOW); 
digitalWrite(IN2, LOW);
digitalWrite(IN3, HIGH);
digitalWrite(IN4, HIGH);
break; 
case 2:
digitalWrite(IN1, LOW); 
digitalWrite(IN2, LOW);
digitalWrite(IN3, HIGH);
digitalWrite(IN4, LOW);
break; 
case 3:
digitalWrite(IN1, LOW); 
digitalWrite(IN2, HIGH);
digitalWrite(IN3, HIGH);
digitalWrite(IN4, LOW);
break; 
case 4:
digitalWrite(IN1, LOW); 
digitalWrite(IN2, HIGH);
digitalWrite(IN3, LOW);
digitalWrite(IN4, LOW);
break; 
case 5:
digitalWrite(IN1, HIGH); 
digitalWrite(IN2, HIGH);
digitalWrite(IN3, LOW);
digitalWrite(IN4, LOW);
break; 
case 6:
digitalWrite(IN1, HIGH); 
digitalWrite(IN2, LOW);
digitalWrite(IN3, LOW);
digitalWrite(IN4, LOW);
break; 
case 7:
digitalWrite(IN1, HIGH); 
digitalWrite(IN2, LOW);
digitalWrite(IN3, LOW);
digitalWrite(IN4, HIGH);
break; 
default:
digitalWrite(IN1, LOW); 
digitalWrite(IN2, LOW);
digitalWrite(IN3, LOW);
digitalWrite(IN4, LOW);
break; 
}
delayMicroseconds(1000);
if(Direction==1){ Steps++;}
if(Direction==0){ Steps--; }
if(Steps>7){Steps=0;}
if(Steps<0){Steps=7; }
} 
}