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Incorporating updates to the Servo library by Michael Margolis.
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@ -45,28 +45,24 @@
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#include <avr/interrupt.h>
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#include <WProgram.h>
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#include "Servo.h"
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#define TICKS_PER_uS (clockCyclesPerMicrosecond() / 8) // number of timer ticks per microsecond with prescale of 8
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#define usToTicks(_us) (( clockCyclesPerMicrosecond()* _us) / 8) // converts microseconds to tick (assumes prescale of 8) // 12 Aug 2009
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#define ticksToUs(_ticks) (( (unsigned)_ticks * 8)/ clockCyclesPerMicrosecond() ) // converts from ticks back to microseconds
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#define SERVOS_PER_TIMER 12 // the maximum number of servos controlled by one timer
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#define TRIM_DURATION (SERVOS_PER_TIMER/2) // compensation ticks to trim adjust for digitalWrite delays
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#define NBR_TIMERS (MAX_SERVOS / SERVOS_PER_TIMER)
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#define TRIM_DURATION 2 // compensation ticks to trim adjust for digitalWrite delays // 12 August 2009
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static servo_t servos[MAX_SERVOS]; // static array of servo structures
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static volatile int8_t Channel[NBR_TIMERS]; // counter for the servo being pulsed for each timer (or -1 if refresh interval)
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#if defined(__AVR_ATmega1280__)
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typedef enum { _timer5, _timer1, _timer3, _timer4 } servoTimer_t; // this is the sequence for timer utilization on mega
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#else
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typedef enum { _timer1 } servoTimer_t; // this is the sequence for timer utilization on other controllers
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#endif
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//#define NBR_TIMERS (MAX_SERVOS / SERVOS_PER_TIMER)
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static servo_t servos[MAX_SERVOS]; // static array of servo structures
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static volatile int8_t Channel[_Nbr_16timers ]; // counter for the servo being pulsed for each timer (or -1 if refresh interval)
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uint8_t ServoCount = 0; // the total number of attached servos
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// convenience macros
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#define SERVO_INDEX_TO_TIMER(_servo_nbr) ((servoTimer_t)(_servo_nbr / SERVOS_PER_TIMER)) // returns the timer controlling this servo
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#define SERVO_INDEX_TO_TIMER(_servo_nbr) ((timer16_Sequence_t)(_servo_nbr / SERVOS_PER_TIMER)) // returns the timer controlling this servo
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#define SERVO_INDEX_TO_CHANNEL(_servo_nbr) (_servo_nbr % SERVOS_PER_TIMER) // returns the index of the servo on this timer
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#define SERVO_INDEX(_timer,_channel) ((_timer*SERVOS_PER_TIMER) + _channel) // macro to access servo index by timer and channel
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#define SERVO(_timer,_channel) (servos[SERVO_INDEX(_timer,_channel)]) // macro to access servo class by timer and channel
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@ -76,7 +72,7 @@ uint8_t ServoCount = 0; // the total number
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/************ static functions common to all instances ***********************/
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static inline void handle_interrupts(servoTimer_t timer, volatile uint16_t *TCNTn, volatile uint16_t* OCRnA)
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static inline void handle_interrupts(timer16_Sequence_t timer, volatile uint16_t *TCNTn, volatile uint16_t* OCRnA)
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{
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if( Channel[timer] < 0 )
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*TCNTn = 0; // channel set to -1 indicated that refresh interval completed so reset the timer
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@ -93,64 +89,112 @@ static inline void handle_interrupts(servoTimer_t timer, volatile uint16_t *TCNT
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}
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else {
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// finished all channels so wait for the refresh period to expire before starting over
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if( (unsigned)*TCNTn < (((unsigned int)REFRESH_INTERVAL * TICKS_PER_uS) + 4) ) // allow a few ticks to ensure the next OCR1A not missed
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*OCRnA = (unsigned int)REFRESH_INTERVAL * TICKS_PER_uS;
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if( (unsigned)*TCNTn < (usToTicks(REFRESH_INTERVAL) + 4) ) // allow a few ticks to ensure the next OCR1A not missed
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*OCRnA = (unsigned int)usToTicks(REFRESH_INTERVAL);
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else
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*OCRnA = *TCNTn + 4; // at least REFRESH_INTERVAL has elapsed
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Channel[timer] = -1; // this will get incremented at the end of the refresh period to start again at the first channel
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}
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}
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#ifndef WIRING // Wiring pre-defines signal handlers so don't define any if compiling for the Wiring platform
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// Interrupt handlers for Arduino
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#if defined(_useTimer1)
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SIGNAL (TIMER1_COMPA_vect)
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{
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handle_interrupts(_timer1, &TCNT1, &OCR1A);
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}
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#endif
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#if defined(__AVR_ATmega1280__)
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#if defined(_useTimer3)
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SIGNAL (TIMER3_COMPA_vect)
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{
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handle_interrupts(_timer3, &TCNT3, &OCR3A);
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}
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#endif
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#if defined(_useTimer4)
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SIGNAL (TIMER4_COMPA_vect)
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{
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handle_interrupts(_timer4, &TCNT4, &OCR4A);
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}
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#endif
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#if defined(_useTimer5)
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SIGNAL (TIMER5_COMPA_vect)
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{
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handle_interrupts(_timer5, &TCNT5, &OCR5A);
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}
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#endif
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static void initISR(servoTimer_t timer)
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#elif defined WIRING
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// Interrupt handlers for Wiring
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#if defined(_useTimer1)
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void Timer1Service()
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{
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handle_interrupts(_timer1, &TCNT1, &OCR1A);
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}
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#endif
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#if defined(_useTimer3)
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void Timer3Service()
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{
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handle_interrupts(_timer3, &TCNT3, &OCR3A);
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}
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#endif
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#endif
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static void initISR(timer16_Sequence_t timer)
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{
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#if defined (_useTimer1)
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if(timer == _timer1) {
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TCCR1A = 0; // normal counting mode
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TCCR1B = _BV(CS11); // set prescaler of 8
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TCNT1 = 0; // clear the timer count
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#if defined(__AVR_ATmega8__)
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#if defined(__AVR_ATmega8__)|| defined(__AVR_ATmega128__)
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TIFR |= _BV(OCF1A); // clear any pending interrupts;
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TIMSK |= _BV(OCIE1A) ; // enable the output compare interrupt
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TIMSK |= _BV(OCIE1A) ; // enable the output compare interrupt
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#else
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// here if not ATmega8 or ATmega128
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TIFR1 |= _BV(OCF1A); // clear any pending interrupts;
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TIMSK1 |= _BV(OCIE1A) ; // enable the output compare interrupt
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#endif
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#endif
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#if defined(WIRING)
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timerAttach(TIMER1OUTCOMPAREA_INT, Timer1Service);
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#endif
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}
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#if defined(__AVR_ATmega1280__)
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else if(timer == _timer3) {
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#endif
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#if defined (_useTimer3)
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if(timer == _timer3) {
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TCCR3A = 0; // normal counting mode
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TCCR3B = _BV(CS31); // set prescaler of 8
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TCNT3 = 0; // clear the timer count
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#if defined(__AVR_ATmega128__)
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TIFR |= _BV(OCF3A); // clear any pending interrupts;
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ETIMSK |= _BV(OCIE3A); // enable the output compare interrupt
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#else
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TIFR3 = _BV(OCF3A); // clear any pending interrupts;
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TIMSK3 = _BV(OCIE3A) ; // enable the output compare interrupt
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#endif
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#if defined(WIRING)
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timerAttach(TIMER3OUTCOMPAREA_INT, Timer3Service); // for Wiring platform only
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#endif
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}
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else if(timer == _timer4) {
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#endif
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#if defined (_useTimer4)
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if(timer == _timer4) {
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TCCR4A = 0; // normal counting mode
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TCCR4B = _BV(CS41); // set prescaler of 8
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TCNT4 = 0; // clear the timer count
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TIFR4 = _BV(OCF4A); // clear any pending interrupts;
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TIMSK4 = _BV(OCIE4A) ; // enable the output compare interrupt
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}
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else if(timer == _timer5) {
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TIMSK4 = _BV(OCIE4A) ; // enable the output compare interrupt
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}
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#endif
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#if defined (_useTimer5)
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if(timer == _timer5) {
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TCCR5A = 0; // normal counting mode
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TCCR5B = _BV(CS51); // set prescaler of 8
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TCNT5 = 0; // clear the timer count
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@ -160,7 +204,32 @@ static void initISR(servoTimer_t timer)
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#endif
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}
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static boolean isTimerActive(servoTimer_t timer)
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static void finISR(timer16_Sequence_t timer)
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{
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//disable use of the given timer
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#if defined WIRING // Wiring
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if(timer == _timer1) {
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#if defined(__AVR_ATmega1281__)||defined(__AVR_ATmega2561__)
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TIMSK1 &= ~_BV(OCIE1A) ; // disable timer 1 output compare interrupt
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#else
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TIMSK &= ~_BV(OCIE1A) ; // disable timer 1 output compare interrupt
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#endif
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timerDetach(TIMER1OUTCOMPAREA_INT);
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}
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else if(timer == _timer3) {
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#if defined(__AVR_ATmega1281__)||defined(__AVR_ATmega2561__)
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TIMSK3 &= ~_BV(OCIE3A); // disable the timer3 output compare A interrupt
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#else
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ETIMSK &= ~_BV(OCIE3A); // disable the timer3 output compare A interrupt
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#endif
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timerDetach(TIMER3OUTCOMPAREA_INT);
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}
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#else
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//For arduino - in future: call here to a currently undefined function to reset the timer
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#endif
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}
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static boolean isTimerActive(timer16_Sequence_t timer)
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{
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// returns true if any servo is active on this timer
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for(uint8_t channel=0; channel < SERVOS_PER_TIMER; channel++) {
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@ -177,7 +246,7 @@ Servo::Servo()
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{
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if( ServoCount < MAX_SERVOS) {
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this->servoIndex = ServoCount++; // assign a servo index to this instance
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servos[this->servoIndex].ticks = DEFAULT_PULSE_WIDTH * TICKS_PER_uS; // store default values
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servos[this->servoIndex].ticks = usToTicks(DEFAULT_PULSE_WIDTH); // store default values - 12 Aug 2009
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}
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else
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this->servoIndex = INVALID_SERVO ; // too many servos
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@ -197,7 +266,7 @@ uint8_t Servo::attach(int pin, int min, int max)
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this->min = (MIN_PULSE_WIDTH - min)/4; //resolution of min/max is 4 uS
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this->max = (MAX_PULSE_WIDTH - max)/4;
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// initialize the timer if it has not already been initialized
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servoTimer_t timer = SERVO_INDEX_TO_TIMER(servoIndex);
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timer16_Sequence_t timer = SERVO_INDEX_TO_TIMER(servoIndex);
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if(isTimerActive(timer) == false)
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initISR(timer);
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servos[this->servoIndex].Pin.isActive = true; // this must be set after the check for isTimerActive
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@ -208,12 +277,10 @@ uint8_t Servo::attach(int pin, int min, int max)
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void Servo::detach()
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{
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servos[this->servoIndex].Pin.isActive = false;
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#ifdef FREE_TIMERS
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if(isTimerActive(SERVO_INDEX_TO_TIMER(servoIndex)) == false) {
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;// call to unimplimented function in wiring.c to re-init timer (set timer back to PWM mode) TODO?
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timer16_Sequence_t timer = SERVO_INDEX_TO_TIMER(servoIndex);
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if(isTimerActive(timer) == false) {
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finISR(timer);
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}
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#endif
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}
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void Servo::write(int value)
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@ -238,7 +305,9 @@ void Servo::writeMicroseconds(int value)
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else if( value > SERVO_MAX() )
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value = SERVO_MAX();
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value = (value-TRIM_DURATION) * TICKS_PER_uS; // convert to ticks after compensating for interrupt overhead
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value = value - TRIM_DURATION;
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value = usToTicks(value); // convert to ticks after compensating for interrupt overhead - 12 Aug 2009
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uint8_t oldSREG = SREG;
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cli();
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servos[channel].ticks = value;
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@ -255,7 +324,7 @@ int Servo::readMicroseconds()
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{
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unsigned int pulsewidth;
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if( this->servoIndex != INVALID_SERVO )
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pulsewidth = (servos[this->servoIndex].ticks / TICKS_PER_uS) + TRIM_DURATION ;
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pulsewidth = ticksToUs(servos[this->servoIndex].ticks) + TRIM_DURATION ; // 12 aug 2009
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else
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pulsewidth = 0;
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@ -23,7 +23,8 @@
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The servos are pulsed in the background using the value most recently written using the write() method
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Note that analogWrite of PWM on pins associated with the timer are disabled when the first servo is attached.
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Timers are siezed as needed in groups of 12 servos - 24 servos use two timers, 48 servos will use four.
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Timers are seized as needed in groups of 12 servos - 24 servos use two timers, 48 servos will use four.
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The sequence used to sieze timers is defined in timers.h
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The methods are:
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@ -46,6 +47,43 @@
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#include <inttypes.h>
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/*
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* Defines for 16 bit timers used with Servo library
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*
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* If _useTimerX is defined then TimerX is a 16 bit timer on the curent board
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* timer16_Sequence_t enumerates the sequence that the timers should be allocated
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* _Nbr_16timers indicates how many 16 bit timers are available.
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*
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*/
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// Say which 16 bit timers can be used and in what order
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#if defined(__AVR_ATmega1280__)
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#define _useTimer5
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#define _useTimer1
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#define _useTimer3
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#define _useTimer4
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typedef enum { _timer5, _timer1, _timer3, _timer4, _Nbr_16timers } timer16_Sequence_t ;
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#elif defined(__AVR_ATmega32U4__)
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#define _useTimer3
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#define _useTimer1
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typedef enum { _timer3, _timer1, _Nbr_16timers } timer16_Sequence_t ;
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#elif defined(__AVR_AT90USB646__) || defined(__AVR_AT90USB1286__)
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#define _useTimer3
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#define _useTimer1
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typedef enum { _timer3, _timer1, _Nbr_16timers } timer16_Sequence_t ;
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#elif defined(__AVR_ATmega128__) ||defined(__AVR_ATmega1281__)||defined(__AVR_ATmega2561__)
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#define _useTimer3
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#define _useTimer1
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typedef enum { _timer3, _timer1, _Nbr_16timers } timer16_Sequence_t ;
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#else // everything else
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#define _useTimer1
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typedef enum { _timer1, _Nbr_16timers } timer16_Sequence_t ;
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#endif
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#define Servo_VERSION 2 // software version of this library
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#define MIN_PULSE_WIDTH 544 // the shortest pulse sent to a servo
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@ -53,11 +91,8 @@
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#define DEFAULT_PULSE_WIDTH 1500 // default pulse width when servo is attached
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#define REFRESH_INTERVAL 20000 // minumim time to refresh servos in microseconds
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#if defined(__AVR_ATmega1280__)
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#define MAX_SERVOS 48 // the maximum number of servos (valid range is from 1 to 48)
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#else
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#define MAX_SERVOS 12 // this library supports up to 12 on a standard Arduino
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#endif
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#define SERVOS_PER_TIMER 12 // the maximum number of servos controlled by one timer
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#define MAX_SERVOS (_Nbr_16timers * SERVOS_PER_TIMER)
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#define INVALID_SERVO 255 // flag indicating an invalid servo index
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