marlin/Marlin/servo.cpp

/**
 * Marlin 3D Printer Firmware
 * Copyright (C) 2016 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
 *
 * Based on Sprinter and grbl.
 * Copyright (C) 2011 Camiel Gubbels / Erik van der Zalm
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

/**
 * servo.cpp - Interrupt driven Servo library for Arduino using 16 bit timers- Version 2
 * Copyright (c) 2009 Michael Margolis.  All right reserved.
 */

/**
 * A servo is activated by creating an instance of the Servo class passing the desired pin to the attach() method.
 * The servos are pulsed in the background using the value most recently written using the write() method
 *
 * Note that analogWrite of PWM on pins associated with the timer are disabled when the first servo is attached.
 * Timers are seized as needed in groups of 12 servos - 24 servos use two timers, 48 servos will use four.
 *
 * The methods are:
 *
 * Servo - Class for manipulating servo motors connected to Arduino pins.
 *
 * attach(pin)           - Attach a servo motor to an i/o pin.
 * attach(pin, min, max) - Attach to a pin, setting min and max values in microseconds
 *                         Default min is 544, max is 2400
 *
 * write()               - Set the servo angle in degrees. (Invalid angles —over MIN_PULSE_WIDTH— are treated as µs.)
 * writeMicroseconds()   - Set the servo pulse width in microseconds.
 * move(pin, angle)      - Sequence of attach(pin), write(angle), delay(SERVO_DELAY).
 *                         With DEACTIVATE_SERVOS_AFTER_MOVE it detaches after SERVO_DELAY.
 * read()                - Get the last-written servo pulse width as an angle between 0 and 180.
 * readMicroseconds()    - Get the last-written servo pulse width in microseconds.
 * attached()            - Return true if a servo is attached.
 * detach()              - Stop an attached servo from pulsing its i/o pin.
 *
 */
#include "MarlinConfig.h"

#if HAS_SERVOS

#include <avr/interrupt.h>
#include <Arduino.h>

#include "servo.h"

#define usToTicks(_us)    (( clockCyclesPerMicrosecond()* _us) / 8)     // converts microseconds to tick (assumes prescale of 8)  // 12 Aug 2009
#define ticksToUs(_ticks) (( (unsigned)_ticks * 8)/ clockCyclesPerMicrosecond() ) // converts from ticks back to microseconds

#define TRIM_DURATION       2                               // compensation ticks to trim adjust for digitalWrite delays // 12 August 2009

//#define NBR_TIMERS        ((MAX_SERVOS) / (SERVOS_PER_TIMER))

static ServoInfo_t servo_info[MAX_SERVOS];                  // static array of servo info structures
static volatile int8_t Channel[_Nbr_16timers ];             // counter for the servo being pulsed for each timer (or -1 if refresh interval)

uint8_t ServoCount = 0;                                     // the total number of attached servos


// convenience macros
#define SERVO_INDEX_TO_TIMER(_servo_nbr) ((timer16_Sequence_t)(_servo_nbr / (SERVOS_PER_TIMER))) // returns the timer controlling this servo
#define SERVO_INDEX_TO_CHANNEL(_servo_nbr) (_servo_nbr % (SERVOS_PER_TIMER))       // returns the index of the servo on this timer
#define SERVO_INDEX(_timer,_channel)  ((_timer*(SERVOS_PER_TIMER)) + _channel)     // macro to access servo index by timer and channel
#define SERVO(_timer,_channel)  (servo_info[SERVO_INDEX(_timer,_channel)])       // macro to access servo class by timer and channel

#define SERVO_MIN() (MIN_PULSE_WIDTH - this->min * 4)  // minimum value in uS for this servo
#define SERVO_MAX() (MAX_PULSE_WIDTH - this->max * 4)  // maximum value in uS for this servo

/************ static functions common to all instances ***********************/

static inline void handle_interrupts(timer16_Sequence_t timer, volatile uint16_t* TCNTn, volatile uint16_t* OCRnA) {
  if (Channel[timer] < 0)
    *TCNTn = 0; // channel set to -1 indicated that refresh interval completed so reset the timer
  else {
    if (SERVO_INDEX(timer, Channel[timer]) < ServoCount && SERVO(timer, Channel[timer]).Pin.isActive)
      digitalWrite(SERVO(timer, Channel[timer]).Pin.nbr, LOW); // pulse this channel low if activated
  }

  Channel[timer]++;    // increment to the next channel
  if (SERVO_INDEX(timer, Channel[timer]) < ServoCount && Channel[timer] < SERVOS_PER_TIMER) {
    *OCRnA = *TCNTn + SERVO(timer, Channel[timer]).ticks;
    if (SERVO(timer, Channel[timer]).Pin.isActive)    // check if activated
      digitalWrite(SERVO(timer, Channel[timer]).Pin.nbr, HIGH); // its an active channel so pulse it high
  }
  else {
    // finished all channels so wait for the refresh period to expire before starting over
    if (((unsigned)*TCNTn) + 4 < usToTicks(REFRESH_INTERVAL))    // allow a few ticks to ensure the next OCR1A not missed
      *OCRnA = (unsigned int)usToTicks(REFRESH_INTERVAL);
    else
      *OCRnA = *TCNTn + 4;  // at least REFRESH_INTERVAL has elapsed
    Channel[timer] = -1; // this will get incremented at the end of the refresh period to start again at the first channel
  }
}

#ifndef WIRING // Wiring pre-defines signal handlers so don't define any if compiling for the Wiring platform

  // Interrupt handlers for Arduino
  #if ENABLED(_useTimer1)
    SIGNAL (TIMER1_COMPA_vect) { handle_interrupts(_timer1, &TCNT1, &OCR1A); }
  #endif

  #if ENABLED(_useTimer3)
    SIGNAL (TIMER3_COMPA_vect) { handle_interrupts(_timer3, &TCNT3, &OCR3A); }
  #endif

  #if ENABLED(_useTimer4)
    SIGNAL (TIMER4_COMPA_vect) { handle_interrupts(_timer4, &TCNT4, &OCR4A); }
  #endif

  #if ENABLED(_useTimer5)
    SIGNAL (TIMER5_COMPA_vect) { handle_interrupts(_timer5, &TCNT5, &OCR5A); }
  #endif

#else // WIRING

  // Interrupt handlers for Wiring
  #if ENABLED(_useTimer1)
    void Timer1Service() { handle_interrupts(_timer1, &TCNT1, &OCR1A); }
  #endif
  #if ENABLED(_useTimer3)
    void Timer3Service() { handle_interrupts(_timer3, &TCNT3, &OCR3A); }
  #endif

#endif // WIRING


static void initISR(timer16_Sequence_t timer) {
  #if ENABLED(_useTimer1)
    if (timer == _timer1) {
      TCCR1A = 0;             // normal counting mode
      TCCR1B = _BV(CS11);     // set prescaler of 8
      TCNT1 = 0;              // clear the timer count
      #if defined(__AVR_ATmega8__)|| defined(__AVR_ATmega128__)
        SBI(TIFR, OCF1A);      // clear any pending interrupts;
        SBI(TIMSK, OCIE1A);    // enable the output compare interrupt
      #else
        // here if not ATmega8 or ATmega128
        SBI(TIFR1, OCF1A);     // clear any pending interrupts;
        SBI(TIMSK1, OCIE1A);   // enable the output compare interrupt
      #endif
      #ifdef WIRING
        timerAttach(TIMER1OUTCOMPAREA_INT, Timer1Service);
      #endif
    }
  #endif

  #if ENABLED(_useTimer3)
    if (timer == _timer3) {
      TCCR3A = 0;             // normal counting mode
      TCCR3B = _BV(CS31);     // set prescaler of 8
      TCNT3 = 0;              // clear the timer count
      #ifdef __AVR_ATmega128__
        SBI(TIFR, OCF3A);     // clear any pending interrupts;
        SBI(ETIMSK, OCIE3A);  // enable the output compare interrupt
      #else
        SBI(TIFR3, OCF3A);   // clear any pending interrupts;
        SBI(TIMSK3, OCIE3A); // enable the output compare interrupt
      #endif
      #ifdef WIRING
        timerAttach(TIMER3OUTCOMPAREA_INT, Timer3Service);  // for Wiring platform only
      #endif
    }
  #endif

  #if ENABLED(_useTimer4)
    if (timer == _timer4) {
      TCCR4A = 0;             // normal counting mode
      TCCR4B = _BV(CS41);     // set prescaler of 8
      TCNT4 = 0;              // clear the timer count
      TIFR4 = _BV(OCF4A);     // clear any pending interrupts;
      TIMSK4 = _BV(OCIE4A);   // enable the output compare interrupt
    }
  #endif

  #if ENABLED(_useTimer5)
    if (timer == _timer5) {
      TCCR5A = 0;             // normal counting mode
      TCCR5B = _BV(CS51);     // set prescaler of 8
      TCNT5 = 0;              // clear the timer count
      TIFR5 = _BV(OCF5A);     // clear any pending interrupts;
      TIMSK5 = _BV(OCIE5A);   // enable the output compare interrupt
    }
  #endif
}

static void finISR(timer16_Sequence_t timer) {
  // Disable use of the given timer
  #ifdef WIRING
    if (timer == _timer1) {
      CBI(
        #if defined(__AVR_ATmega1281__) || defined(__AVR_ATmega2561__)
          TIMSK1
        #else
          TIMSK
        #endif
          , OCIE1A);    // disable timer 1 output compare interrupt
      timerDetach(TIMER1OUTCOMPAREA_INT);
    }
    else if (timer == _timer3) {
      CBI(
        #if defined(__AVR_ATmega1281__) || defined(__AVR_ATmega2561__)
          TIMSK3
        #else
          ETIMSK
        #endif
          , OCIE3A);    // disable the timer3 output compare A interrupt
      timerDetach(TIMER3OUTCOMPAREA_INT);
    }
  #else // !WIRING
    // For arduino - in future: call here to a currently undefined function to reset the timer
    UNUSED(timer);
  #endif
}

static bool isTimerActive(timer16_Sequence_t timer) {
  // returns true if any servo is active on this timer
  for (uint8_t channel = 0; channel < SERVOS_PER_TIMER; channel++) {
    if (SERVO(timer, channel).Pin.isActive)
      return true;
  }
  return false;
}


/****************** end of static functions ******************************/

Servo::Servo() {
  if (ServoCount < MAX_SERVOS) {
    this->servoIndex = ServoCount++;                    // assign a servo index to this instance
    servo_info[this->servoIndex].ticks = usToTicks(DEFAULT_PULSE_WIDTH);   // store default values  - 12 Aug 2009
  }
  else
    this->servoIndex = INVALID_SERVO;  // too many servos
}

int8_t Servo::attach(int pin) {
  return this->attach(pin, MIN_PULSE_WIDTH, MAX_PULSE_WIDTH);
}

int8_t Servo::attach(int pin, int min, int max) {

  if (this->servoIndex >= MAX_SERVOS) return -1;

  if (pin > 0) servo_info[this->servoIndex].Pin.nbr = pin;
  pinMode(servo_info[this->servoIndex].Pin.nbr, OUTPUT); // set servo pin to output

  // todo min/max check: abs(min - MIN_PULSE_WIDTH) /4 < 128
  this->min = (MIN_PULSE_WIDTH - min) / 4; //resolution of min/max is 4 uS
  this->max = (MAX_PULSE_WIDTH - max) / 4;

  // initialize the timer if it has not already been initialized
  timer16_Sequence_t timer = SERVO_INDEX_TO_TIMER(servoIndex);
  if (!isTimerActive(timer)) initISR(timer);
  servo_info[this->servoIndex].Pin.isActive = true;  // this must be set after the check for isTimerActive

  return this->servoIndex;
}

void Servo::detach() {
  servo_info[this->servoIndex].Pin.isActive = false;
  timer16_Sequence_t timer = SERVO_INDEX_TO_TIMER(servoIndex);
  if (!isTimerActive(timer)) finISR(timer);
}

void Servo::write(int value) {
  if (value < MIN_PULSE_WIDTH) { // treat values less than 544 as angles in degrees (valid values in microseconds are handled as microseconds)
    value = map(constrain(value, 0, 180), 0, 180, SERVO_MIN(), SERVO_MAX());
  }
  this->writeMicroseconds(value);
}

void Servo::writeMicroseconds(int value) {
  // calculate and store the values for the given channel
  byte channel = this->servoIndex;
  if (channel < MAX_SERVOS) {  // ensure channel is valid
    // ensure pulse width is valid
    value = constrain(value, SERVO_MIN(), SERVO_MAX()) - (TRIM_DURATION);
    value = usToTicks(value);  // convert to ticks after compensating for interrupt overhead - 12 Aug 2009

    CRITICAL_SECTION_START;
    servo_info[channel].ticks = value;
    CRITICAL_SECTION_END;
  }
}

// return the value as degrees
int Servo::read() { return map(this->readMicroseconds() + 1, SERVO_MIN(), SERVO_MAX(), 0, 180); }

int Servo::readMicroseconds() {
  return (this->servoIndex == INVALID_SERVO) ? 0 : ticksToUs(servo_info[this->servoIndex].ticks) + TRIM_DURATION;
}

bool Servo::attached() { return servo_info[this->servoIndex].Pin.isActive; }

void Servo::move(int value) {
  if (this->attach(0) >= 0) {
    this->write(value);
    delay(SERVO_DELAY);
    #if ENABLED(DEACTIVATE_SERVOS_AFTER_MOVE)
      this->detach();
    #endif
  }
}

#endif