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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 <wirish/boards.h>
#include <wirish/io.h>
#include <wirish/pwm.h>
#include <wirish/wirish_math.h>
// 20 millisecond period config. For a 1-based prescaler,
//
// (prescaler * overflow / CYC_MSEC) msec = 1 timer cycle = 20 msec
// => prescaler * overflow = 20 * CYC_MSEC
//
// This picks the smallest prescaler that allows an overflow < 2^16.
#define MAX_OVERFLOW ((1 << 16) - 1)
#define CYC_MSEC (1000 * CYCLES_PER_MICROSECOND)
#define TAU_MSEC 20
#define TAU_USEC (TAU_MSEC * 1000)
#define TAU_CYC (TAU_MSEC * CYC_MSEC)
#define SERVO_PRESCALER (TAU_CYC / MAX_OVERFLOW + 1)
#define SERVO_OVERFLOW ((uint16)round((double)TAU_CYC / SERVO_PRESCALER))
// Unit conversions
#define US_TO_COMPARE(us) ((uint16)map((us), 0, TAU_USEC, 0, SERVO_OVERFLOW))
#define COMPARE_TO_US(c) ((uint32)map((c), 0, SERVO_OVERFLOW, 0, TAU_USEC))
#define ANGLE_TO_US(a) ((uint16)(map((a), this->minAngle, this->maxAngle, \
this->minPW, this->maxPW)))
#define US_TO_ANGLE(us) ((int16)(map((us), this->minPW, this->maxPW, \
this->minAngle, this->maxAngle)))
Servo::Servo() {
this->resetFields();
}
bool Servo::attach(uint8 pin,
uint16 minPW,
uint16 maxPW,
int16 minAngle,
int16 maxAngle) {
timer_dev *tdev = PIN_MAP[pin].timer_device;
if (tdev == NULL) {
// don't reset any fields or ASSERT(0), to keep driving any
// previously attach()ed servo.
return false;
}
if (this->attached()) {
this->detach();
}
this->pin = pin;
this->minPW = minPW;
this->maxPW = maxPW;
this->minAngle = minAngle;
this->maxAngle = maxAngle;
pinMode(pin, PWM);
timer_pause(tdev);
timer_set_prescaler(tdev, SERVO_PRESCALER - 1); // prescaler is 1-based
timer_set_reload(tdev, SERVO_OVERFLOW);
timer_generate_update(tdev);
timer_resume(tdev);
return true;
}
bool Servo::detach() {
if (!this->attached()) {
return false;
}
timer_dev *tdev = PIN_MAP[this->pin].timer_device;
uint8 tchan = PIN_MAP[this->pin].timer_channel;
timer_set_mode(tdev, tchan, TIMER_DISABLED);
this->resetFields();
return true;
}
void Servo::write(int degrees) {
degrees = constrain(degrees, this->minAngle, this->maxAngle);
this->writeMicroseconds(ANGLE_TO_US(degrees));
}
int Servo::read() const {
int a = US_TO_ANGLE(this->readMicroseconds());
// map() round-trips in a weird way we mostly correct for here;
// the round-trip is still sometimes off-by-one for write(1) and
// write(179).
return a == this->minAngle || a == this->maxAngle ? a : a + 1;
}
void Servo::writeMicroseconds(uint16 pulseWidth) {
if (!this->attached()) {
ASSERT(0);
return;
}
pulseWidth = constrain(pulseWidth, this->minPW, this->maxPW);
pwmWrite(this->pin, US_TO_COMPARE(pulseWidth));
}
uint16 Servo::readMicroseconds() const {
if (!this->attached()) {
ASSERT(0);
return 0;
}
stm32_pin_info pin_info = PIN_MAP[this->pin];
uint16 compare = timer_get_compare(pin_info.timer_device,
pin_info.timer_channel);
return COMPARE_TO_US(compare);
}
void Servo::resetFields(void) {
this->pin = NOT_ATTACHED;
this->minAngle = SERVO_DEFAULT_MIN_ANGLE;
this->maxAngle = SERVO_DEFAULT_MAX_ANGLE;
this->minPW = SERVO_DEFAULT_MIN_PW;
this->maxPW = SERVO_DEFAULT_MAX_PW;
}
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