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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.
*****************************************************************************/
#ifndef _SERVO_H_
#define _SERVO_H_
#include <libmaple/libmaple_types.h>
#include <libmaple/timer.h>
#include <wirish/wirish_types.h>
/*
* Note on Arduino compatibility:
*
* In the Arduino implementation, PWM is done "by hand" in the sense
* that timer channels are hijacked in groups and an ISR is set which
* toggles Servo::attach()ed pins using digitalWrite().
*
* While this scheme allows any pin to drive a servo, it chews up
* cycles and complicates the programmer's notion of when a particular
* timer channel will be in use.
*
* This implementation only allows Servo instances to attach() to pins
* that already have a timer channel associated with them, and just
* uses pwmWrite() to drive the wave.
*
* This introduces an incompatibility: while the Arduino
* implementation of attach() returns the affected channel on success
* and 0 on failure, this one returns true on success and false on
* failure.
*
* RC Servos expect a pulse every 20ms. Since periods are set for
* entire timers, rather than individual channels, attach()ing a Servo
* to a pin can interfere with other pins associated with the same
* timer. As always, your board's pin map is your friend.
*/
// Pin number of unattached pins
#define NOT_ATTACHED (-1)
// Default min/max pulse widths (in microseconds) and angles (in
// degrees). Values chosen for Arduino compatibility. These values
// are part of the public API; DO NOT CHANGE THEM.
#define SERVO_DEFAULT_MIN_PW 544
#define SERVO_DEFAULT_MAX_PW 2400
#define SERVO_DEFAULT_MIN_ANGLE 0
#define SERVO_DEFAULT_MAX_ANGLE 180
/** Class for interfacing with RC servomotors. */
class Servo {
public:
/**
* @brief Construct a new Servo instance.
*
* The new instance will not be attached to any pin.
*/
Servo();
/**
* @brief Associate this instance with a servomotor whose input is
* connected to pin.
*
* If this instance is already attached to a pin, it will be
* detached before being attached to the new pin. This function
* doesn't detach any interrupt attached with the pin's timer
* channel.
*
* @param pin Pin connected to the servo pulse wave input. This
* pin must be capable of PWM output.
*
* @param minPulseWidth Minimum pulse width to write to pin, in
* microseconds. This will be associated
* with a minAngle degree angle. Defaults to
* SERVO_DEFAULT_MIN_PW = 544.
*
* @param maxPulseWidth Maximum pulse width to write to pin, in
* microseconds. This will be associated
* with a maxAngle degree angle. Defaults to
* SERVO_DEFAULT_MAX_PW = 2400.
*
* @param minAngle Target angle (in degrees) associated with
* minPulseWidth. Defaults to
* SERVO_DEFAULT_MIN_ANGLE = 0.
*
* @param maxAngle Target angle (in degrees) associated with
* maxPulseWidth. Defaults to
* SERVO_DEFAULT_MAX_ANGLE = 180.
*
* @sideeffect May set pinMode(pin, PWM).
*
* @return true if successful, false when pin doesn't support PWM.
*/
bool attach(uint8 pin,
uint16 minPulseWidth=SERVO_DEFAULT_MIN_PW,
uint16 maxPulseWidth=SERVO_DEFAULT_MAX_PW,
int16 minAngle=SERVO_DEFAULT_MIN_ANGLE,
int16 maxAngle=SERVO_DEFAULT_MAX_ANGLE);
/**
* @brief Check if this instance is attached to a servo.
* @return true if this instance is attached to a servo, false otherwise.
* @see Servo::attachedPin()
*/
bool attached() const { return this->pin != NOT_ATTACHED; }
/**
* @brief Get the pin this instance is attached to.
* @return Pin number if currently attached to a pin, NOT_ATTACHED
* otherwise.
* @see Servo::attach()
*/
int attachedPin() const { return this->pin; }
/**
* @brief Stop driving the servo pulse train.
*
* If not currently attached to a motor, this function has no effect.
*
* @return true if this call did anything, false otherwise.
*/
bool detach();
/**
* @brief Set the servomotor target angle.
*
* @param angle Target angle, in degrees. If the target angle is
* outside the range specified at attach() time, it
* will be clamped to lie in that range.
*
* @see Servo::attach()
*/
void write(int angle);
/**
* Get the servomotor's target angle, in degrees. This will
* lie inside the range specified at attach() time.
*
* @see Servo::attach()
*/
int read() const;
/**
* @brief Set the pulse width, in microseconds.
*
* @param pulseWidth Pulse width to send to the servomotor, in
* microseconds. If outside of the range
* specified at attach() time, it is clamped to
* lie in that range.
*
* @see Servo::attach()
*/
void writeMicroseconds(uint16 pulseWidth);
/**
* Get the current pulse width, in microseconds. This will
* lie within the range specified at attach() time.
*
* @see Servo::attach()
*/
uint16 readMicroseconds() const;
private:
int16 pin;
uint16 minPW;
uint16 maxPW;
int16 minAngle;
int16 maxAngle;
void resetFields(void);
};
#endif /* _SERVO_H_ */
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