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#include <avr/io.h>
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#include "motor.h"
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#include <stdlib.h>
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/*
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motor controller
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IN1: PD7
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IN2: PD6
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PWM: PB1
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*/
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int8_t motor_speed;
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void motor_init(void)
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{
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  // WGM1 0b0101 (fast PWM, 8-bit)
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  // COM1A 0b10 (clear OC1A on compare match, set on BOTTOM)
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  // CS1 0b011 (64 prescaler)
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  TCCR1A = _BV(WGM10) | _BV(COM1A1);
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  TCCR1B = _BV(WGM12) | _BV(CS11) | _BV(CS10);
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  OCR1AH = 0;
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  // set IN1 (PD7), IN2 (PD6), and PWM (PB1) as output
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  DDRD |= _BV(DDD7) | _BV(DDD6);
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  DDRB |= _BV(DDB1);
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  set_motor(0);
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}
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void set_motor(int8_t speed)
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/* Speed must be between -127 and 127 */
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{
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  motor_speed = speed;
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  OCR1AL = (uint8_t)abs(speed)*2;
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  if(speed>0) //go forwards
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  {
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    PORTD |= (1<<PD7);
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    PORTD = PORTD & ~(1<<PD6);
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  }  
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  if(speed<0) //go backwards
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  {
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    PORTD |= (1<<PD6);
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    PORTD = PORTD & ~(1<<PD7);
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  }
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  if(speed==0) // turn motor off
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  {
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    PORTD = PORTD & ~(1<<PD6);
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    PORTD = PORTD & ~(1<<PD7);
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  }
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}
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int8_t get_motor()
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{
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  return motor_speed;
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}