Speed Control of Stepper Motor using PIC microcontroller

To control the speed of unipolar stepper motor we use a Microcontroller to control the activation and also control activation time. ULN2003 is used as current amplifier. Preset use to control speed of motor

Circuit to speed control of stepper motor

connection of stepper motor

connection of stepper motor to control circuit

1 - coil 1

2 - coil 2

3 - coil 3

4 - coil 4

&

5 - CMN

CODE:-

unsigned short i,k;                            // Globle variable initialisation

void delay(unsigned short j)                                   // Delay function
{
 for(i=0;i<=j;i++)                        // For loop to generate multiple delay
 {
  delay_ms(1);                                                      // delay 1ms
 }
}

void main()                                                     // Main function
{
 ANSEL = 0x00;                                      // Analog selection register
 TRISA = 0x07;                                // Input/output selection register
 TRISC = 0x00;                                // Input/output selection register
 PORTC = 0x00;                                  // Default PORTC all output zero

 a = 0;                                                        // bit a is clear

 ADC_Init();                                                   // initialise ADC

 while(1)                                                            // Inf loop
 {
  k = 20 - ADC_Read(0)/60;   // Formula to generat delay by read ADC at analog 0

  PORTC=0x01;                       //
  delay(k);                         //
  PORTC=0x04;                       //
  Delay(k);                         // 

  PORTC=0x02;                       //
  Delay(k);                         //
  PORTC=0x08;                       //
  Delay(k);                         //
 }
}