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9b437d7c5e
* The default timings were chosen vastly outside specification. On COTS servos, this causes much confusion for the user, because a wide range of angle starting from 0 degress, and a just a large range of angle leading up to 180 degrees, is dead - in fact, the servo doesn't move at all, from any position. Not investigated further for obvious reasons, as this may have also destroyed servos that ran hot trying to abide by the PWM signal but could not mechanically! * Change timing limits to safe values. With previous default timings and safety limits, popular servos could force against internal physical endstops, which could overload and destroy them. * Review action: revert changes to hard boundary for min/max duty cycle timings. Internal review, fix/drop legacy comments. * A Servo on each available ESP8266 GPIO (D0-D8), no observed interference. * Remove possible jerk due to force-cancelling duty cycle. * Overload attach: can specify initial angle for servo, too. * Stricter checks for configured, and default, bounded timings. * Missed the min/max in a comment. * Default microsecond lower bound of 1000 causes confusing behavior - 200 is minimum enforced elsewhere, so use it here too as nearest multiple of 100 from 180. * Comment rationale for changed defaults of min/max pulse widths. Comment rationale for changed defaults of min/max pulse widths.
96 lines
4.4 KiB
C++
96 lines
4.4 KiB
C++
/*
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Servo.h - Interrupt driven Servo library for Esp8266 using timers
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Original Copyright (c) 2015 Michael C. Miller. All right reserved.
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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// A servo is activated by creating an instance of the Servo class passing
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// the desired pin to the attach() method.
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// The servos are pulsed in the background using the value most recently
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// written using the write() method.
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//
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// The methods are:
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//
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// Servo - Class for manipulating servo motors connected to Arduino pins.
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//
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// attach(pin) - Attaches a servo motor to an i/o pin.
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// attach(pin, min, max) - Attaches to a pin setting min and max values in microseconds
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// default min is 1000, max is 2000
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//
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// write() - Sets the servo angle in degrees. (invalid angle that is valid as pulse in microseconds is treated as microseconds)
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// writeMicroseconds() - Sets the servo pulse width in microseconds
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// read() - Gets the last written servo pulse width as an angle between 0 and 180.
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// readMicroseconds() - Gets the last written servo pulse width in microseconds. (was read_us() in first release)
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// attached() - Returns true if there is a servo attached.
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// detach() - Stops an attached servos from pulsing its i/o pin.
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#ifndef Servo_h
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#define Servo_h
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#include <Arduino.h>
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// The following values are in us (microseconds).
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// Since the defaults can be overwritten in the new attach() member function,
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// they were modified from the Arduino AVR defaults to be in the safe range
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// of publically available specifications. While this implies that many 180°
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// servos do not operate the full 0° to 180° sweep using these, it also prevents
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// unsuspecting damage. For Arduino AVR, the same change is being discussed.
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#define DEFAULT_MIN_PULSE_WIDTH 1000 // uncalibrated default, the shortest duty cycle sent to a servo
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#define DEFAULT_MAX_PULSE_WIDTH 2000 // uncalibrated default, the longest duty cycle sent to a servo
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#define DEFAULT_NEUTRAL_PULSE_WIDTH 1500 // default duty cycle when servo is attached
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#define REFRESH_INTERVAL 20000 // classic default period to refresh servos in microseconds
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#define MAX_SERVOS 9 // D0-D8
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#if !defined(ESP8266)
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#error "This library only supports esp8266 boards."
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#endif
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class Servo
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{
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public:
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Servo();
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~Servo();
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// attach the given pin to the next free channel, sets pinMode, returns channel number or 0 if failure.
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// returns channel number or 0 if failure.
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uint8_t attach(int pin);
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// attach the given pin to the next free channel, sets pinMode, min, and max values for write().
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// returns channel number or 0 if failure.
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uint8_t attach(int pin, uint16_t min, uint16_t max);
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// attach the given pin to the next free channel, sets pinMode, min, and max values for write(),
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// and sets the initial value, the same as write().
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// returns channel number or 0 if failure.
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uint8_t attach(int pin, uint16_t min, uint16_t max, int value);
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void detach();
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void write(int value); // if value is < 200 its treated as an angle, otherwise as pulse width in microseconds
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void writeMicroseconds(int value); // Write pulse width in microseconds
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int read(); // returns current pulse width as an angle between 0 and 180 degrees
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int readMicroseconds(); // returns current pulse width in microseconds for this servo (was read_us() in first release)
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bool attached(); // return true if this servo is attached, otherwise false
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private:
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static uint32_t _servoMap;
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bool _attached;
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uint8_t _pin;
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uint16_t _minUs;
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uint16_t _maxUs;
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uint16_t _valueUs;
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};
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#endif
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