#include <mega8.h>
#include <mega8_bits.h>

// Global variables.
unsigned char RunClockwise = 1; //!< Start with clockwise rotation.
unsigned char IPM_B4_PWM = 0xFF; //!< Control signals to IPM driver chip.

// Function prototypes.
void main(void);
void initialization(void);
void PWM2_initialize(void);     
void ADC_setup(void);

//! Initialize I/O-ports, ADC and PWM output.
void initialization(void)
{
     PORTB= ~0x3f; // 6 bits of PORTB to be high
     DDRB = 0x3f; // set PORTB6 bits as output
     ADC_setup(); // Initialize the ADC
     PWM2_initialize(); // Initialize PWM2.
}

//! Initialize ADC to CPU/4 speed, channel 5, free running mode.
void ADC_setup(void)
{
     ADCSRA = (1<<ADEN)|(1<<ADPS1)|(1<<ADATE)|(1<<ADSC); //Enable ADC, ADC clk = CK/4, free running.
//    ADMUX = 0x05 | (1<<REFS0) | (1<<ADLAR); // Channel 5 with AVCC as ref.
     ADMUX = 0x05 | (0<<REFS0) | (1<<ADLAR); // Channel 5 with AREF as ref.
}

//! Initialize PWM output OC2B from Timer/Counter2 at 20kHz base freq @ 8MHz CPU.
void PWM2_initialize(void)
{
     TCCR2A = (1<<COM2B1)|(1<<COM2B0)| // Set OC2B (DIP pin 5) on Compare Match,
              (0<<WGM21)|(1<<WGM20);   // phase correct PWM & OCR2A as TOP.
     TCCR2B = (1<<WGM22)|(0<<CS22)|(0<<CS21)|(1<<CS20);
     OCR2A  = 200; // 200 decimal TOP.
     OCR2B  = 100; // This starts PWM output at 50%
         
     DDRD |= (1<<DDB3);
}

//! Pin Change Interrupt for PORTC (PCINT8..14).
interrupt [PORTB1] void Pin_Change_Int_Serv(void)
{
     static unsigned char Hall_In;
         
     Hall_In = PINC & 0x07;
         
     if( RunClockwise ) {
      // This is clockwise Switch statement.
      // Based on Hall inputs select 1 of 6 patterns to
      // send to IPM via main().
      switch(Hall_In) {
       case 1: IPM_B4_PWM = 0b101011; break;
       case 5: IPM_B4_PWM = 0b110011; break;
       case 4: IPM_B4_PWM = 0b110101; break;
       case 6: IPM_B4_PWM = 0b011101; break;
       case 2: IPM_B4_PWM = 0b011110; break;
       case 3: IPM_B4_PWM = 0b101110; break;
           
       // All outputs off if illegal Hall sensors.
       default: IPM_B4_PWM = 0b111111;
      }
     } else {
      // This is counter-clockwise Switch statement.
      // Based on Hall inputs, select 1 of 6 patterns to
      // send to IPM via main().
      switch(Hall_In) {
       case 6: IPM_B4_PWM = 0b011110; break;
       case 4: IPM_B4_PWM = 0b011101; break;
       case 5: IPM_B4_PWM = 0b110101; break;
       case 1: IPM_B4_PWM = 0b110011; break;
       case 3: IPM_B4_PWM = 0b101011; break;
       case 2: IPM_B4_PWM = 0b101110; break;

       // All outputs off if illegal Hall sensors.
       default: IPM_B4_PWM = 0b111111;
      }
     }
}

//! Application starts here.
void main(void)
{
     unsigned char speed;
         
     initialization(); // Initialize Peripherals.
         
     // Set up and Enable Interrupts
     PCMSK1 = (1<<PCINT10) | (1<<PCINT9)| (1<<PCINT8);
     PCICR = (1<<PCIE1);// Enable Pin Change Ints from port C.
         
     // Start interrupts by forcing Hall Inputs to 0, then switching pins to inputs.
     DDRC = 7; // 3 Hall Inputs pulled to 0 volts.
     PORTC = 0;
     PORTC = 1;
     PORTC = 2;
     PORTC = 4; // Start interrupts with forced pin change
     DDRC = 0; // Port C switched back to all inputs.     
     SREG |= 0x80;// Enable Interrupts  via SEI bit
         
     PORTD |= (1<<PORTD0) | (1<<PORTD1); // Direction control input pullups, undocumented.
         
     while(1) { // IPM_B4_PWM is updated via a Pin Change Interrupt
         
                    // Direction control, undocumented.
             if( !(PIND & (1<<PORTD0)) ) RunClockwise = 1;
             if( !(PIND & (1<<PORTD1)) ) RunClockwise = 0;
         
             // Update speed setting from ADC reading.
                    speed = ADCH;
                    if( speed > 199 ) speed = 199;
                    OCR2B = speed;
          
       // If OC2B is high, send inactive outputs to IPM.
      if( PIND & (1 << PORTD3) ) {
       PORTB = ~0xFF; // <== If motor driver has active high inputs.
//   PORTB = 0xFF; // <== If motor driver has active low inputs.
      } else {
       PORTB = ~IPM_B4_PWM; // <== If motor driver has active high inputs.
//   PORTB = IPM_B4_PWM; // <== If motor driver has active low inputs.
      }
     }
}