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Arduino-Development / libraries /Servo /src /samd /Servo.cpp
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Archive original Arduino development files (part 9)
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/*
Copyright (c) 2015 Arduino LLC. 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
*/
#if defined(ARDUINO_ARCH_SAMD)
#include <Arduino.h>
#include <Servo.h>
#define usToTicks(_us) ((clockCyclesPerMicrosecond() * _us) / 16) // converts microseconds to tick
#define ticksToUs(_ticks) (((unsigned) _ticks * 16) / clockCyclesPerMicrosecond()) // converts from ticks back to microseconds
#define TRIM_DURATION 5 // 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 currentServoIndex[_Nbr_16timers]; // index 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
#define WAIT_TC16_REGS_SYNC(x) while(x->COUNT16.STATUS.bit.SYNCBUSY);
/************ static functions common to all instances ***********************/
void Servo_Handler(timer16_Sequence_t timer, Tc *pTc, uint8_t channel, uint8_t intFlag);
#if defined (_useTimer1)
void HANDLER_FOR_TIMER1(void) {
Servo_Handler(_timer1, TC_FOR_TIMER1, CHANNEL_FOR_TIMER1, INTFLAG_BIT_FOR_TIMER_1);
}
#endif
#if defined (_useTimer2)
void HANDLER_FOR_TIMER2(void) {
Servo_Handler(_timer2, TC_FOR_TIMER2, CHANNEL_FOR_TIMER2, INTFLAG_BIT_FOR_TIMER_2);
}
#endif
void Servo_Handler(timer16_Sequence_t timer, Tc *tc, uint8_t channel, uint8_t intFlag)
{
if (currentServoIndex[timer] < 0) {
tc->COUNT16.COUNT.reg = (uint16_t) 0;
WAIT_TC16_REGS_SYNC(tc)
} else {
if (SERVO_INDEX(timer, currentServoIndex[timer]) < ServoCount && SERVO(timer, currentServoIndex[timer]).Pin.isActive == true) {
digitalWrite(SERVO(timer, currentServoIndex[timer]).Pin.nbr, LOW); // pulse this channel low if activated
}
}
// Select the next servo controlled by this timer
currentServoIndex[timer]++;
if (SERVO_INDEX(timer, currentServoIndex[timer]) < ServoCount && currentServoIndex[timer] < SERVOS_PER_TIMER) {
if (SERVO(timer, currentServoIndex[timer]).Pin.isActive == true) { // check if activated
digitalWrite(SERVO(timer, currentServoIndex[timer]).Pin.nbr, HIGH); // it's an active channel so pulse it high
}
// Get the counter value
uint16_t tcCounterValue = tc->COUNT16.COUNT.reg;
WAIT_TC16_REGS_SYNC(tc)
tc->COUNT16.CC[channel].reg = (uint16_t) (tcCounterValue + SERVO(timer, currentServoIndex[timer]).ticks);
WAIT_TC16_REGS_SYNC(tc)
}
else {
// finished all channels so wait for the refresh period to expire before starting over
// Get the counter value
uint16_t tcCounterValue = tc->COUNT16.COUNT.reg;
WAIT_TC16_REGS_SYNC(tc)
if (tcCounterValue + 4UL < usToTicks(REFRESH_INTERVAL)) { // allow a few ticks to ensure the next OCR1A not missed
tc->COUNT16.CC[channel].reg = (uint16_t) usToTicks(REFRESH_INTERVAL);
}
else {
tc->COUNT16.CC[channel].reg = (uint16_t) (tcCounterValue + 4UL); // at least REFRESH_INTERVAL has elapsed
}
WAIT_TC16_REGS_SYNC(tc)
currentServoIndex[timer] = -1; // this will get incremented at the end of the refresh period to start again at the first channel
}
// Clear the interrupt
tc->COUNT16.INTFLAG.reg = intFlag;
}
static inline void resetTC (Tc* TCx)
{
// Disable TCx
TCx->COUNT16.CTRLA.reg &= ~TC_CTRLA_ENABLE;
WAIT_TC16_REGS_SYNC(TCx)
// Reset TCx
TCx->COUNT16.CTRLA.reg = TC_CTRLA_SWRST;
WAIT_TC16_REGS_SYNC(TCx)
while (TCx->COUNT16.CTRLA.bit.SWRST);
}
static void _initISR(Tc *tc, uint8_t channel, uint32_t id, IRQn_Type irqn, uint8_t gcmForTimer, uint8_t intEnableBit)
{
// Enable GCLK for timer 1 (timer counter input clock)
GCLK->CLKCTRL.reg = (uint16_t) (GCLK_CLKCTRL_CLKEN | GCLK_CLKCTRL_GEN_GCLK0 | GCLK_CLKCTRL_ID(gcmForTimer));
while (GCLK->STATUS.bit.SYNCBUSY);
// Reset the timer
// TODO this is not the right thing to do if more than one channel per timer is used by the Servo library
resetTC(tc);
// Set timer counter mode to 16 bits
tc->COUNT16.CTRLA.reg |= TC_CTRLA_MODE_COUNT16;
// Set timer counter mode as normal PWM
tc->COUNT16.CTRLA.reg |= TC_CTRLA_WAVEGEN_NPWM;
// Set the prescaler factor to GCLK_TC/16. At nominal 48 MHz GCLK_TC this is 3000 ticks per millisecond
tc->COUNT16.CTRLA.reg |= TC_CTRLA_PRESCALER_DIV16;
// Count up
tc->COUNT16.CTRLBCLR.bit.DIR = 1;
WAIT_TC16_REGS_SYNC(tc)
// First interrupt request after 1 ms
tc->COUNT16.CC[channel].reg = (uint16_t) usToTicks(1000UL);
WAIT_TC16_REGS_SYNC(tc)
// Configure interrupt request
// TODO this should be changed if more than one channel per timer is used by the Servo library
NVIC_DisableIRQ(irqn);
NVIC_ClearPendingIRQ(irqn);
NVIC_SetPriority(irqn, 0);
NVIC_EnableIRQ(irqn);
// Enable the match channel interrupt request
tc->COUNT16.INTENSET.reg = intEnableBit;
// Enable the timer and start it
tc->COUNT16.CTRLA.reg |= TC_CTRLA_ENABLE;
WAIT_TC16_REGS_SYNC(tc)
}
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, GCM_FOR_TIMER_1, INTENSET_BIT_FOR_TIMER_1);
#endif
#if defined (_useTimer2)
if (timer == _timer2)
_initISR(TC_FOR_TIMER2, CHANNEL_FOR_TIMER2, ID_TC_FOR_TIMER2, IRQn_FOR_TIMER2, GCM_FOR_TIMER_2, INTENSET_BIT_FOR_TIMER_2);
#endif
}
static void finISR(timer16_Sequence_t timer)
{
#if defined (_useTimer1)
// Disable the match channel interrupt request
TC_FOR_TIMER1->COUNT16.INTENCLR.reg = INTENCLR_BIT_FOR_TIMER_1;
#endif
#if defined (_useTimer2)
// Disable the match channel interrupt request
TC_FOR_TIMER2->COUNT16.INTENCLR.reg = INTENCLR_BIT_FOR_TIMER_2;
#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;
}
#endif // ARDUINO_ARCH_SAMD