317 lines
11 KiB
C++
317 lines
11 KiB
C++
/*
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Servo.cpp - Interrupt driven Servo library for Arduino using 16 bit timers- Version 2
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Copyright (c) 2009 Michael Margolis. All right reserved.
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <avr/interrupt.h>
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#include "Arduino.h"
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#include "Servo.h"
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#if defined(ARDUINO_ARCH_AVR)
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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 TRIM_DURATION 2 // compensation ticks to trim adjust for digitalWrite delays // 12 August 2009
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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) ((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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#define SERVO_MIN() (MIN_PULSE_WIDTH - this->min * 4) // minimum value in uS for this servo
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#define SERVO_MAX() (MAX_PULSE_WIDTH - this->max * 4) // maximum value in uS for this servo
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/************ static functions common to all instances ***********************/
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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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else{
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if( SERVO_INDEX(timer,Channel[timer]) < ServoCount && SERVO(timer,Channel[timer]).Pin.isActive == true )
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digitalWrite( SERVO(timer,Channel[timer]).Pin.nbr,LOW); // pulse this channel low if activated
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}
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Channel[timer]++; // increment to the next channel
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if( SERVO_INDEX(timer,Channel[timer]) < ServoCount && Channel[timer] < SERVOS_PER_TIMER) {
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*OCRnA = *TCNTn + SERVO(timer,Channel[timer]).ticks;
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if(SERVO(timer,Channel[timer]).Pin.isActive == true) // check if activated
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digitalWrite( SERVO(timer,Channel[timer]).Pin.nbr,HIGH); // its an active channel so pulse it high
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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) + 4 < usToTicks(REFRESH_INTERVAL) ) // 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(_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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#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__)|| 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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#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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#if defined(WIRING)
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timerAttach(TIMER1OUTCOMPAREA_INT, Timer1Service);
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#endif
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}
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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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#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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#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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TIFR5 = _BV(OCF5A); // clear any pending interrupts;
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TIMSK5 = _BV(OCIE5A) ; // enable the output compare interrupt
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}
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#endif
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}
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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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if(SERVO(timer,channel).Pin.isActive == true)
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return true;
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}
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return false;
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}
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/****************** end of static functions ******************************/
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Servo::Servo(void)
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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 = 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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}
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uint8_t Servo::attach(int pin)
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{
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return this->attach(pin, MIN_PULSE_WIDTH, MAX_PULSE_WIDTH);
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}
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uint8_t Servo::attach(int pin, int min, int max)
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{
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if(this->servoIndex < MAX_SERVOS ) {
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pinMode( pin, OUTPUT) ; // set servo pin to output
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servos[this->servoIndex].Pin.nbr = pin;
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// todo min/max check: abs(min - MIN_PULSE_WIDTH) /4 < 128
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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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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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}
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return this->servoIndex ;
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}
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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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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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}
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void Servo::write(int value)
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{
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if(value < MIN_PULSE_WIDTH)
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{ // treat values less than 544 as angles in degrees (valid values in microseconds are handled as microseconds)
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if(value < 0) value = 0;
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if(value > 180) value = 180;
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value = map(value, 0, 180, SERVO_MIN(), SERVO_MAX());
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}
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this->writeMicroseconds(value);
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}
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void Servo::writeMicroseconds(int value)
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{
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// calculate and store the values for the given channel
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byte channel = this->servoIndex;
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if( (channel < MAX_SERVOS) ) // ensure channel is valid
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{
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if( value < SERVO_MIN() ) // ensure pulse width is valid
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value = SERVO_MIN();
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else if( value > SERVO_MAX() )
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value = SERVO_MAX();
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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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SREG = oldSREG;
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}
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}
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int Servo::read() // return the value as degrees
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{
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return map( this->readMicroseconds()+1, SERVO_MIN(), SERVO_MAX(), 0, 180);
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}
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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 = 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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return pulsewidth;
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}
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bool Servo::attached()
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{
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return servos[this->servoIndex].Pin.isActive ;
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}
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#endif // ARDUINO_ARCH_AVR
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