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/******************************************************************************
* The MIT License
*
* Copyright (c) 2010, LeafLabs, LLC.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*****************************************************************************/
#include "Servo.h"
#include "boards.h"
#include "io.h"
#include "pwm.h"
#include "wirish_math.h"
// Configure prescaler and overflow for a 20msec period (could just
// use HardwareTimer::setPeriod(), but this lets conversions below
// happen more statically, in combination with an inlined map() -- a
// premature optimization? TODO profile speed/size tradeoff)
#define CYC_20MSEC (20000 * CYCLES_PER_MICROSECOND)
#define SERVO_PRE ((uint16)((CYC_20MSEC >> 16) + 1))
#define SERVO_OVF ((uint16)((CYC_20MSEC / SERVO_PRE) - 1))
#define SERVO_TAU_USEC \
((uint32)(((double)SERVO_OVF) * SERVO_PRE / CYCLES_PER_MICROSECOND + 0.5))
#define US_TO_COMPARE(us) ((uint16)map(us, 0, SERVO_TAU_USEC, 0, SERVO_OVF))
#define COMPARE_TO_US(c) ((uint32)map(c, 0, SERVO_OVF, 0, SERVO_TAU_USEC))
#define ANGLE_TO_US(a) ((uint16)(map(a, 0, 180, this->min, this->max)))
#define US_TO_ANGLE(us) ((uint8)(map(us, this->min, this->max, 0, 180)))
Servo::Servo() {
this->pin = NOT_ATTACHED;
this->timer = 0;
this->channel = TIMER_INVALID;
this->min = SERVO_DEFAULT_MIN_PW;
this->max = SERVO_DEFAULT_MAX_PW;
}
bool Servo::attach(uint8_t pin) {
return this->attach(pin, SERVO_DEFAULT_MIN_PW, SERVO_DEFAULT_MAX_PW);
}
bool Servo::attach(uint8_t pin, uint16_t min, uint16_t max) {
timer_dev_num timer_num = PIN_MAP[pin].timer_num;
uint32_t channel = PIN_MAP[pin].timer_chan;
if (timer_num == TIMER_INVALID) {
// don't reset any members or ASSERT(0), to keep driving any
// previously attach()ed servo.
return false;
}
this->pin = pin;
this->timer = getTimer(timer_num);
this->channel = channel;
this->min = min;
this->max = max;
pinMode(pin, PWM);
this->timer->pause();
this->timer->setPrescaleFactor(SERVO_PRE);
this->timer->setOverflow(SERVO_OVF);
this->timer->generateUpdate();
this->timer->resume();
return true;
}
bool Servo::detach() {
if (this->pin == NOT_ATTACHED) return false;
this->timer->setChannelMode(this->channel, TIMER_DISABLED);
this->pin = NOT_ATTACHED;
this->timer = 0;
this->channel = TIMER_INVALID;
this->min = SERVO_DEFAULT_MIN_PW;
this->max = SERVO_DEFAULT_MAX_PW;
return true;
}
void Servo::write(unsigned int value) {
if (value < SERVO_MAX_WRITE_ANGLE) {
this->writeMicroseconds(ANGLE_TO_US(value));
} else {
this->writeMicroseconds(value);
}
}
void Servo::writeMicroseconds(uint16_t pulseWidth) {
if (this->pin == NOT_ATTACHED) {
ASSERT(0);
return;
}
pulseWidth = constrain(pulseWidth, this->min, this->max);
pwmWrite(this->pin, US_TO_COMPARE(pulseWidth));
}
int Servo::read() const {
if (this->pin == NOT_ATTACHED) {
ASSERT(0);
return 0;
}
unsigned int pw = this->readMicroseconds();
int a = US_TO_ANGLE(pw);
// map() round-trips in a weird way we correct for here
return a == 0 || a == 180 ? a : a + 1;
}
uint16_t Servo::readMicroseconds() const {
if (this->pin == NOT_ATTACHED) {
ASSERT(0);
return 0;
}
unsigned int compare = this->timer->getCompare(this->channel);
uint16_t c = COMPARE_TO_US(compare);
// map() round-trips in a weird way we correct for here
return c == 0 || c == 180 ? c : c + 1;
}
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