Unipolar Stepper Motor Control From IR Remote Control Using PIC18F4550

// Remote controlled stepper motor using PIC18F4550 CCS C code
// http://ccspicc.blogspot.com/
// [email protected]

#include <18F4550.h>
#fuses NOMCLR INTRC_IO
#use delay(clock = 8000000)
#use fast_io(B)
#use fast_io(D)

short Direction;
unsigned int8 step_number = 0, speed_delay = 2;
unsigned int32 remote_code;
#INT_TIMER1                                  // Timer1 interrupt ISR
void timer1_isr(void){
  remote_code = 0;
  clear_interrupt(INT_TIMER1);
  disable_interrupts(INT_TIMER1);
}
#INT_EXT                                     // External interrupt ISR
void ext_isr(void){
  unsigned int8 count = 0, i;
  unsigned int32 ir_code;
  // Check 9ms pulse (remote control sends logic high)
  while((input(PIN_B0) == 0) && (count < 200)){
    count++;
    delay_us(50);}
  if( (count > 199) || (count < 160))        // NEC protocol?
    return;                          
  count = 0;
  // Check 4.5ms space or repeated code
  while((input(PIN_B0)) && (count < 100)){
    count++;
    delay_us(50);}
  if( (count > 99) || (count < 30))          // NEC protocol?
    return;
  // Check repeated code
  if(count < 60){
    count = 0;
    while((input(PIN_B0) == 0) && (count < 14)){
      count++;
      delay_us(50);}
    if( (count > 13) || (count < 8))         // NEC protocol?
      return;
    if((remote_code == 0x40BF50AF) || (remote_code == 0x40BF906F))
    set_timer1(0);
  }
  // Read message (32 bits)
  for(i = 0; i < 32; i++){
    count = 0;
    while((input(PIN_B0) == 0) && (count < 14)){
      count++;
      delay_us(50);}
    if( (count > 13) || (count < 8))         // NEC protocol?
      return;                          
    count = 0;
    while((input(PIN_B0)) && (count < 40)){
      count++;
      delay_us(50);}
    if( (count > 39) || (count < 8))         // NEC protocol?
      return;                           
    if( count > 20)                          // If space width > 1ms
      bit_set(ir_code, (31 - i));            // Write 1 to bit (31 - i)
    else                                     // If space width < 1ms
      bit_clear(ir_code, (31 - i));          // Write 0 to bit (31 - i)
  }
  if((ir_code == 0x40BF50AF) || (ir_code == 0x40BF906F)){
    set_timer1(0);
    clear_interrupt(INT_TIMER1);
    enable_interrupts(INT_TIMER1);}
  if(ir_code == 0x40BFA05F){
    speed_delay++;
    if(speed_delay > 20) speed_delay = 20;
    return;}
  if(ir_code == 0x40BF609F){
    speed_delay--;
    if(speed_delay < 2) speed_delay = 2;
    return;}
  remote_code = ir_code; 
}
void stepper(int8 step){
  if(Direction == 0){
    switch(step){
      case 0:
        output_d(0b00000011);
        break;
      case 1:
        output_d(0b00000110);
        break;
      case 2:
        output_d(0b00001100);
        break;
      case 3:
        output_d(0b00001001);
        break;
    }
  }
  if(Direction == 1){
    switch(step){
      case 0:
        output_d(0b00001001);
        break;
      case 1:
        output_d(0b00001100);
        break;
      case 2:
        output_d(0b00000110);
        break;
      case 3:
        output_d(0b00000011);
        break;
    }
  }
}
void main(){
  setup_oscillator(OSC_8MHZ);                 // Set internal oscillator to 8MHz
  setup_adc_ports(NO_ANALOGS);                // Configure AN pins as digital
  set_tris_b(1);                           // Configure RB0 as digital input pin
  port_b_pullups(TRUE);                       // Enable PORTB internal pull-ups
  output_d(0);                                // PORTD initial state
  set_tris_d(0);                              // Configure PORTD pins as outputs
  setup_timer_1(T1_INTERNAL | T1_DIV_BY_4);   // Timer1 configuration
  enable_interrupts(GLOBAL);                  // Enable global interrupts
  enable_interrupts(INT_EXT_H2L);                 // Enable external interrupt
  while(TRUE){
    output_d(0);
    while(remote_code == 0x40BF40BF){
      Direction = 0;
      stepper(step_number);
      step_number++;
      if(step_number > 3) 
        step_number = 0;
      delay_ms(speed_delay);
    }
    while(remote_code == 0x40BF807F){
      Direction = 1;
      stepper(step_number);
      step_number++;
      if(step_number > 3) 
        step_number = 0;
      delay_ms(speed_delay);
    }
    while(remote_code == 0x40BF50AF){
      Direction = 0;
      stepper(step_number);
      step_number++;
      if(step_number > 3) 
        step_number = 0;
      delay_ms(speed_delay);
    }
    while(remote_code == 0x40BF906F){
      Direction = 1;
      stepper(step_number);
      step_number++;
      if(step_number > 3) 
        step_number = 0;
      delay_ms(speed_delay);
    }
  }
}