Added Servo library for Arduino Due

Author: cmaglie

libraries/Servo/Servo.cpp

@@ -0,0 +1,310 @@
+/*
+ Servo.cpp - Interrupt driven Servo library for Arduino using 16 bit timers- Version 2
+ Copyright (c) 2009 Michael Margolis.  All right reserved.
+ 
+ This library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+ 
+ This library 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
+ Lesser General Public License for more details.
+ 
+ You should have received a copy of the GNU Lesser General Public
+ License along with this library; if not, write to the Free Software
+ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+/* 
+ 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 )  - Attaches a servo motor to an i/o pin.
+ attach(pin, min, max  ) - Attaches to a pin setting min and max values in microseconds
+ default min is 544, max is 2400  
+ 
+ write()     - Sets the servo angle in degrees.  (invalid angle that is valid as pulse in microseconds is treated as microseconds)
+ writeMicroseconds() - Sets the servo pulse width in microseconds 
+ read()      - Gets the last written servo pulse width as an angle between 0 and 180. 
+ readMicroseconds()   - Gets the last written servo pulse width in microseconds. (was read_us() in first release)
+ attached()  - Returns true if there is a servo attached. 
+ detach()    - Stops an attached servos from pulsing its i/o pin. 
+ 
+*/
+
+#include <Arduino.h> 
+#include "Servo.h"
+
+#define usToTicks(_us)    (( clockCyclesPerMicrosecond() * _us) / 32)     // converts microseconds to tick
+#define ticksToUs(_ticks) (( (unsigned)_ticks * 32)/ clockCyclesPerMicrosecond() ) // converts from ticks back to microseconds
+
+
+#define TRIM_DURATION       2                               // compensation ticks to trim adjust for digitalWrite delays
+
+static servo_t servos[MAX_SERVOS];                          // static array of servo structures
+
+uint8_t ServoCount = 0;                                     // the total number of attached servos
+
+static volatile int8_t Channel[_Nbr_16timers ];             // counter for the servo being pulsed for each timer (or -1 if refresh interval)
+
+// 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)  (servos[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 ***********************/
+
+
+//timer16_Sequence_t timer;
+
+//------------------------------------------------------------------------------
+/// Interrupt handler for the TC0 channel 1.
+//------------------------------------------------------------------------------
+void Servo_Handler(timer16_Sequence_t timer, Tc *pTc, uint8_t channel);
+#if defined (_useTimer1)
+void HANDLER_FOR_TIMER1(void) {
+    Servo_Handler(_timer1, TC_FOR_TIMER1, CHANNEL_FOR_TIMER1);
+}
+#endif
+#if defined (_useTimer2)
+void HANDLER_FOR_TIMER2(void) {
+    Servo_Handler(_timer2, TC_FOR_TIMER2, CHANNEL_FOR_TIMER2);
+}
+#endif
+#if defined (_useTimer3)
+void HANDLER_FOR_TIMER3(void) {
+    Servo_Handler(_timer3, TC_FOR_TIMER3, CHANNEL_FOR_TIMER3);
+}
+#endif
+#if defined (_useTimer4)
+void HANDLER_FOR_TIMER4(void) {
+    Servo_Handler(_timer4, TC_FOR_TIMER4, CHANNEL_FOR_TIMER4);
+}
+#endif
+#if defined (_useTimer5)
+void HANDLER_FOR_TIMER5(void) {
+    Servo_Handler(_timer5, TC_FOR_TIMER5, CHANNEL_FOR_TIMER5);
+}
+#endif
+
+void Servo_Handler(timer16_Sequence_t timer, Tc *tc, uint8_t channel)
+{
+    // clear interrupt
+    tc->TC_CHANNEL[channel].TC_SR;
+    if (Channel[timer] < 0) {
+        tc->TC_CHANNEL[channel].TC_CCR |= TC_CCR_SWTRG; // 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 == true) {
+            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) {
+        tc->TC_CHANNEL[channel].TC_RA = tc->TC_CHANNEL[channel].TC_CV + SERVO(timer,Channel[timer]).ticks;
+        if(SERVO(timer,Channel[timer]).Pin.isActive == true) {    // 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( (tc->TC_CHANNEL[channel].TC_CV) + 4 < usToTicks(REFRESH_INTERVAL) ) { // allow a few ticks to ensure the next OCR1A not missed
+            tc->TC_CHANNEL[channel].TC_RA = (unsigned int)usToTicks(REFRESH_INTERVAL);
+        }
+        else {
+            tc->TC_CHANNEL[channel].TC_RA = tc->TC_CHANNEL[channel].TC_CV + 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
+    }
+}
+
+static void _initISR(Tc *tc, uint32_t channel, uint32_t id, IRQn_Type irqn)
+{
+    pmc_enable_periph_clk(id);
+    TC_Configure(tc, channel,
+    		TC_CMR_TCCLKS_TIMER_CLOCK3 | // MCK/32
+            TC_CMR_WAVE |                // Waveform mode
+            TC_CMR_WAVSEL_UP_RC );       // Counter running up and reset when equals to RC
+
+    /* 84MHz, MCK/32, for 1.5ms: 3937 */
+    TC_SetRA(tc, channel, 2625); // 1ms
+
+    /* Configure and enable interrupt */
+    NVIC_EnableIRQ(irqn);
+    // TC_IER_CPAS: RA Compare
+    tc->TC_CHANNEL[channel].TC_IER = TC_IER_CPAS;
+
+    // Enables the timer clock and performs a software reset to start the counting
+    TC_Start(tc, channel);
+}
+
+static void initISR(timer16_Sequence_t timer)
+{
+#if defined (_useTimer1)
+    if (timer == _timer1)
+    	_initISR(TC_FOR_TIMER1, CHANNEL_FOR_TIMER1, ID_TC_FOR_TIMER1, IRQn_FOR_TIMER1);
+#endif    
+#if defined (_useTimer2)
+    if (timer == _timer2)
+    	_initISR(TC_FOR_TIMER2, CHANNEL_FOR_TIMER2, ID_TC_FOR_TIMER2, IRQn_FOR_TIMER2);
+#endif
+#if defined (_useTimer3)
+    if (timer == _timer3)
+    	_initISR(TC_FOR_TIMER3, CHANNEL_FOR_TIMER3, ID_TC_FOR_TIMER3, IRQn_FOR_TIMER3);
+#endif    
+#if defined (_useTimer4)
+    if (timer == _timer4)
+    	_initISR(TC_FOR_TIMER4, CHANNEL_FOR_TIMER4, ID_TC_FOR_TIMER4, IRQn_FOR_TIMER4);
+#endif    
+#if defined (_useTimer5)
+    if (timer == _timer5)
+    	_initISR(TC_FOR_TIMER5, CHANNEL_FOR_TIMER5, ID_TC_FOR_TIMER5, IRQn_FOR_TIMER5);
+#endif    
+} 
+
+static void finISR(timer16_Sequence_t timer)
+{
+#if defined (_useTimer1)
+    TC_Stop(TC_FOR_TIMER1, CHANNEL_FOR_TIMER1);
+#endif    
+#if defined (_useTimer2)
+    TC_Stop(TC_FOR_TIMER2, CHANNEL_FOR_TIMER2);
+#endif    
+#if defined (_useTimer3)
+    TC_Stop(TC_FOR_TIMER3, CHANNEL_FOR_TIMER3);
+#endif    
+#if defined (_useTimer4)
+    TC_Stop(TC_FOR_TIMER4, CHANNEL_FOR_TIMER4);
+#endif    
+#if defined (_useTimer5)
+    TC_Stop(TC_FOR_TIMER5, CHANNEL_FOR_TIMER5);
+#endif    
+}
+
+
+static boolean 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 == true)
+      return true;
+  }
+  return false;
+}
+
+/****************** end of static functions ******************************/
+
+Servo::Servo()
+{
+  if (ServoCount < MAX_SERVOS) {
+    this->servoIndex = ServoCount++;                    // assign a servo index to this instance
+	servos[this->servoIndex].ticks = usToTicks(DEFAULT_PULSE_WIDTH);   // store default values
+  } else {
+    this->servoIndex = INVALID_SERVO;  // too many servos 
+  }
+}
+
+uint8_t Servo::attach(int pin)
+{
+  return this->attach(pin, MIN_PULSE_WIDTH, MAX_PULSE_WIDTH);
+}
+
+uint8_t Servo::attach(int pin, int min, int max)
+{
+  timer16_Sequence_t timer;
+
+  if (this->servoIndex < MAX_SERVOS) {
+    pinMode(pin, OUTPUT);                                   // set servo pin to output
+    servos[this->servoIndex].Pin.nbr = pin;  
+    // 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 
+    timer = SERVO_INDEX_TO_TIMER(servoIndex);
+    if (isTimerActive(timer) == false) {
+      initISR(timer);    
+    }
+    servos[this->servoIndex].Pin.isActive = true;  // this must be set after the check for isTimerActive
+  }
+  return this->servoIndex;
+}
+
+void Servo::detach()  
+{
+  timer16_Sequence_t timer;
+
+  servos[this->servoIndex].Pin.isActive = false;  
+  timer = SERVO_INDEX_TO_TIMER(servoIndex);
+  if(isTimerActive(timer) == false) {
+    finISR(timer);
+  }
+}
+
+void Servo::write(int value)
+{  
+  // treat values less than 544 as angles in degrees (valid values in microseconds are handled as microseconds)
+  if (value < MIN_PULSE_WIDTH)
+  {  
+    if (value < 0)
+      value = 0;
+    else if (value > 180)
+      value = 180;
+
+    value = map(value, 0, 180, SERVO_MIN(), SERVO_MAX());
+  }
+  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
+  {  
+    if (value < SERVO_MIN())          // ensure pulse width is valid
+      value = SERVO_MIN();
+    else if (value > SERVO_MAX())
+      value = SERVO_MAX();   
+
+    value = value - TRIM_DURATION;
+    value = usToTicks(value);  // convert to ticks after compensating for interrupt overhead
+    servos[channel].ticks = value;  
+  }
+}
+
+int Servo::read() // return the value as degrees
+{
+  return map(readMicroseconds()+1, SERVO_MIN(), SERVO_MAX(), 0, 180);
+}
+
+int Servo::readMicroseconds()
+{
+  unsigned int pulsewidth;
+  if (this->servoIndex != INVALID_SERVO)
+    pulsewidth = ticksToUs(servos[this->servoIndex].ticks)  + TRIM_DURATION;
+  else 
+    pulsewidth  = 0;
+
+  return pulsewidth;   
+}
+
+bool Servo::attached()
+{
+  return servos[this->servoIndex].Pin.isActive;
+}
+
+
+