0,0 → 1,104 |
#include <avr/io.h> |
#include <avr/interrupt.h> |
#include "fc.h" |
#include "eeprom.h" |
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volatile int16_t ServoValue = 0; |
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/*****************************************************/ |
/* Initialize Timer 2 */ |
/*****************************************************/ |
// The timer 2 is used to generate the PWM at PD7 (J7) |
// to control a camera servo for pitch compensation. |
void TIMER2_Init(void) |
{ |
uint8_t sreg = SREG; |
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// disable all interrupts before reconfiguration |
cli(); |
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// set PD7 as output of the PWM for pitch servo |
DDRD |=(1<<DDD7); |
PORTD |= (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) |
// PD7: Clear OC2B on Compare Match, set OC2B at BOTTOM, non inverting PWM (Bits: COM2A1 = 1, COM2A0 = 0) |
// PD6: Normal port operation, OC2B disconnected, (Bits: COM2B1 = 0, COM2B0 = 0) |
TCCR2A &= ~((1<<COM2B1)|(1<<COM2B0)|(1<<COM2A0)); |
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/256 = 20MHz / 256 = 78.128 kHz |
// The timer increments from 0x00 to 0xFF with an update rate of 78.128 kHz or 12.8 us |
// hence the timer overflow interrupt frequency is 78.128 kHz / 256 = 305.176 Hz or 3.276 ms |
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// divider 256 (Bits: CS022 = 1, CS21 = 1, CS20 = 0) |
TCCR2B &= ~((1<<FOC2A)|(1<<FOC2B)|(1<<CS20)|(1<<WGM22)); |
TCCR2B |= (1<<CS22)|(1<<CS21); |
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// Initialize the Output Compare Register A used for PWM generation on port PD7. |
OCR2A = 10; //10 * 12.8us = 1.28 ms high time |
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// Initialize the Timer/Counter 2 Register |
TCNT2 = 0; |
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// Timer/Counter 2 Interrupt Mask Register |
// Enable timer output compare match A Interrupt only |
TIMSK2 &= ~((1<<OCIE2B)|(1<<TOIE2)); |
TIMSK2 |= (1<<OCIE2A); |
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SREG = sreg; |
} |
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/*****************************************************/ |
/* Control Servo Position */ |
/*****************************************************/ |
ISR(TIMER2_COMPA_vect) // every OCR2A * 12.8 us (compare match) |
{ |
static uint8_t timer = 10; |
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if(!timer--) |
{ |
// enable PWM on PD7 in non inverting mode |
TCCR2A &= ~(0<<COM2A0); |
TCCR2A |= (1<<COM2A1); |
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ServoValue = FCParam.ServoPitchControl; |
// inverting movment of servo |
if(ParamSet.ServoPitchCompInvert & 0x01) |
{ |
ServoValue += ((int32_t) ParamSet.ServoPitchComp * (IntegralPitch / 128)) / 512; |
} |
else // non inverting movement of servo |
{ |
ServoValue -= ((int32_t) ParamSet.ServoPitchComp * (IntegralPitch / 128)) / 512; |
} |
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// limit servo value to its parameter range definition |
if(ServoValue < ParamSet.ServoPitchMin) |
{ |
ServoValue = ParamSet.ServoPitchMin; |
} |
else if(ServoValue > ParamSet.ServoPitchMax) |
{ |
ServoValue = ParamSet.ServoPitchMax; |
} |
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// update PWM |
OCR2A = ServoValue; |
timer = ParamSet.ServoPitchRefresh; |
} |
else |
{ |
// disable PWM at PD7 |
TCCR2A &= ~((1<<COM2A1)|(1<<COM2A0)); |
// set PD7 to low |
PORTD &= ~(1<<PORTD7); |
} |
} |