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damellisdamellis
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Moving libraries out of arduino platform / core directory and to top-level.
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‎Servo.cpp

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/*
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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 <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 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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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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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_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(servoTimer_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 < (((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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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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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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#if defined(__AVR_ATmega1280__)
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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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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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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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{
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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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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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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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}
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#if defined(__AVR_ATmega1280__)
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else 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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TIFR3 = _BV(OCF3A); // clear any pending interrupts;
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TIMSK3 = _BV(OCIE3A) ; // enable the output compare interrupt
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}
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else 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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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 boolean isTimerActive(servoTimer_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()
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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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}
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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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servoTimer_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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#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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}
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#endif
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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 >= 0) && (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) * TICKS_PER_uS; // convert to ticks after compensating for interrupt overhead
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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 = (servos[this->servoIndex].ticks / TICKS_PER_uS) + TRIM_DURATION ;
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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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}

‎Servo.h

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/*
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Servo.h - 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 siezed 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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#ifndef Servo_h
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#define Servo_h
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#include <inttypes.h>
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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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#define MAX_PULSE_WIDTH 2400 // the longest pulse sent to a servo
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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 INVALID_SERVO 255 // flag indicating an invalid servo index
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typedef struct {
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uint8_t nbr :6 ; // a pin number from 0 to 63
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uint8_t isActive :1 ; // true if this channel is enabled, pin not pulsed if false
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} ServoPin_t ;
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typedef struct {
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ServoPin_t Pin;
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unsigned int ticks;
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} servo_t;
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class Servo
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{
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public:
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Servo();
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uint8_t attach(int pin); // attach the given pin to the next free channel, sets pinMode, returns channel number or 0 if failure
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uint8_t attach(int pin, int min, int max); // as above but also sets min and max values for writes.
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void detach();
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void write(int value); // if value is < 200 its treated as an angle, otherwise as pulse width in microseconds
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void writeMicroseconds(int value); // Write pulse width in microseconds
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int read(); // returns current pulse width as an angle between 0 and 180 degrees
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int readMicroseconds(); // returns current pulse width in microseconds for this servo (was read_us() in first release)
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bool attached(); // return true if this servo is attached, otherwise false
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private:
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uint8_t servoIndex; // index into the channel data for this servo
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int8_t min; // minimum is this value times 4 added to MIN_PULSE_WIDTH
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int8_t max; // maximum is this value times 4 added to MAX_PULSE_WIDTH
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};
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#endif

‎examples/Knob/Knob.pde

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// Controlling a servo position using a potentiometer (variable resistor)
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// by Michal Rinott <http://people.interaction-ivrea.it/m.rinott>
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#include <Servo.h>
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Servo myservo; // create servo object to control a servo
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int potpin = 0; // analog pin used to connect the potentiometer
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int val; // variable to read the value from the analog pin
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void setup()
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{
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myservo.attach(9); // attaches the servo on pin 9 to the servo object
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}
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void loop()
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{
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val = analogRead(potpin); // reads the value of the potentiometer (value between 0 and 1023)
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val = map(val, 0, 1023, 0, 179); // scale it to use it with the servo (value between 0 and 180)
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myservo.write(val); // sets the servo position according to the scaled value
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delay(15); // waits for the servo to get there
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}

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