305 lines
12 KiB
C++
305 lines
12 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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/*
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A servo is activated by creating an instance of the Servo class passing the desired pin to the attach() method.
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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 seized as needed in groups of 12 servos - 24 servos use two timers, 48 servos will use four.
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The methods are:
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Servo - Class for manipulating servo motors connected to Arduino pins.
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attach(pin ) - Attaches a servo motor to an i/o pin.
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attach(pin, min, max ) - Attaches to a pin setting min and max values in microseconds
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default min is 544, max is 2400
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write() - Sets the servo angle in degrees. (invalid angle that is valid as pulse in microseconds is treated as microseconds)
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writeMicroseconds() - Sets the servo pulse width in microseconds
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read() - Gets the last written servo pulse width as an angle between 0 and 180.
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readMicroseconds() - Gets the last written servo pulse width in microseconds. (was read_us() in first release)
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attached() - Returns true if there is a servo attached.
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detach() - Stops an attached servos from pulsing its i/o pin.
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*/
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#include "Configuration.h"
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#ifdef NUM_SERVOS
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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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#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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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)
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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) // 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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#ifdef _useTimer1
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SIGNAL (TIMER1_COMPA_vect) { handle_interrupts(_timer1, &TCNT1, &OCR1A); }
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#endif
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#ifdef _useTimer3
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SIGNAL (TIMER3_COMPA_vect) { handle_interrupts(_timer3, &TCNT3, &OCR3A); }
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#endif
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#ifdef _useTimer4
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SIGNAL (TIMER4_COMPA_vect) { handle_interrupts(_timer4, &TCNT4, &OCR4A); }
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#endif
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#ifdef _useTimer5
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SIGNAL (TIMER5_COMPA_vect) { handle_interrupts(_timer5, &TCNT5, &OCR5A); }
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#endif
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#else //!WIRING
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// Interrupt handlers for Wiring
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#ifdef _useTimer1
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void Timer1Service() { handle_interrupts(_timer1, &TCNT1, &OCR1A); }
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#endif
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#ifdef _useTimer3
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void Timer3Service() { handle_interrupts(_timer3, &TCNT3, &OCR3A); }
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#endif
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#endif //!WIRING
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static void initISR(timer16_Sequence_t timer) {
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#ifdef _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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#ifdef 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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#ifdef _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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#ifdef __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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#ifdef 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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#ifdef _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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#ifdef _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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// Disable use of the given timer
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#ifdef WIRING
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if (timer == _timer1) {
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#if defined(__AVR_ATmega1281__) || defined(__AVR_ATmega2561__)
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TIMSK1
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#else
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TIMSK
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#endif
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&= ~_BV(OCIE1A); // disable timer 1 output compare interrupt
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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
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#else
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ETIMSK
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#endif
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&= ~_BV(OCIE3A); // disable the timer3 output compare A interrupt
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timerDetach(TIMER3OUTCOMPAREA_INT);
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}
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#else //!WIRING
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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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// 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)
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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() {
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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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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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if (this->servoIndex < MAX_SERVOS ) {
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#if defined(ENABLE_AUTO_BED_LEVELING) && (PROBE_SERVO_DEACTIVATION_DELAY > 0)
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if (pin > 0) this->pin = pin; else pin = this->pin;
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#endif
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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)) 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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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)) finISR(timer);
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}
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void Servo::write(int value) {
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if (value < MIN_PULSE_WIDTH) { // 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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// 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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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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// return the value as degrees
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int Servo::read() { return map( this->readMicroseconds()+1, SERVO_MIN(), SERVO_MAX(), 0, 180); }
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int Servo::readMicroseconds() {
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return (this->servoIndex == INVALID_SERVO) ? 0 : ticksToUs(servos[this->servoIndex].ticks) + TRIM_DURATION;
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}
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bool Servo::attached() { return servos[this->servoIndex].Pin.isActive; }
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#endif
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