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#include <avr/io.h>
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#include <avr/interrupt.h>
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#include "fc.h"
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#include "eeprom.h"
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volatile int16_t ServoValue = 0;
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/*****************************************************/
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/*              Initialize Timer 2                   */
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/*****************************************************/
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// The timer 2 is used to generate the PWM at PD7 (J7)
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// to control a camera servo for nick compensation.
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void TIMER2_Init(void)
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{
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        uint8_t sreg = SREG;
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        // disable all interrupts before reconfiguration
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        cli();
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        // set PD7 as output for the PWM
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        DDRD  |=(1<<DDD7);
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        PORTB |= (1<<PORTD7);
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        // Timer/Counter 2 Control Register A
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        // Waveform Generation Mode is Fast PWM (Bits: WGM22 = 0, WGM21 = 1, WGM20 = 1)
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    // PD7: Clear OC2B on Compare Match, set OC2B at BOTTOM, noninverting PWM (Bits: COM2A1 = 1, COM2A0 = 0)
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    // PD6: Normal port operation, OC2B disconnected, (Bits: COM2B1 = 0, COM2B0 = 0)
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        TCCR2A &= ~((1<<COM2B1)|(1<<COM2B0)|(1<<COM2A0));
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    TCCR2A |= (1<<COM2A1)|(1<<WGM21)|(1<<WGM20);
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    // Timer/Counter 2 Control Register B
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        // Set clock divider for timer 2 to SYSKLOCK/8 = 20MHz / 8 = 2.5MHz.
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        // The timer increments from 0x00 to 0xFF with an update rate of 2.5 MHz,
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        // hence the timer overflow interrupt frequency is 2.5 MHz / 256 = 9.765 kHz
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    // divider 8 (Bits: CS022 = 0, CS21 = 1, CS20 = 0)
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        TCCR2B &= ~((1<<FOC2A)|(1<<FOC2B)|(1<<WGM22));
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    TCCR2B = (TCCR2B & 0xF8)|(0<<CS22)|(1<<CS21)|(0<<CS20);
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        // Initialize the Output Compare Register A used for PWM generation on port PD7.
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        OCR2A = 10;
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        // Initialize the Timer/Counter 2 Register
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    TCNT2 = 0;
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        // Timer/Counter 2 Interrupt Mask Register
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        // Enable timer output compare match A Interrupt only
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        TIMSK2 &= ~((1<<OCIE2B)|(1<<TOIE2));
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        TIMSK2 |= (1<<OCIE2A);
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    SREG = sreg;
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}
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/*****************************************************/
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/*              Control Servo Position               */
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/*****************************************************/
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ISR(TIMER2_COMPA_vect)  // 9.765 kHz
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{
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  static uint8_t timer = 10;
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  if(!timer--)
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    {
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     // enable PWM on PD7 in non inverting mode
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     TCCR2A = (TCCR2A & 0x3F)|(1<<COM2A1)|(0<<COM2A0);
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     ServoValue =  Parameter_ServoNickControl;
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     // inverting movment of servo
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     if(ParamSet.ServoNickCompInvert & 0x01)
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     {
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                 ServoValue += ((int32_t) ParamSet.ServoNickComp * (IntegralNick / 128)) / 512;
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         }
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     else // non inverting movement of servo
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     {
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                 ServoValue -= ((int32_t) ParamSet.ServoNickComp * (IntegralNick / 128)) / 512;
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         }
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         // limit servo value to its parameter range definition
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     if(ServoValue < ParamSet.ServoNickMin)
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     {
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                 ServoValue = ParamSet.ServoNickMin;
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         }
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     else if(ServoValue > ParamSet.ServoNickMax)
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     {
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                 ServoValue = ParamSet.ServoNickMax;
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     }
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         // update PWM
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     OCR2A = ServoValue;
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     timer = ParamSet.ServoNickRefresh;
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    }
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    else
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    {
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         // disable PWM at PD7
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     TCCR2A &= ~((1<<COM2A1)|(1<<COM2A0));
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     // set PD7 to low
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     PORTD &= ~(1<<PORTD7);
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    }
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}