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Servo.h - Interrupt driven Servo library for Arduino using 16 bit timers
Copyright (c) 2009 Michael Margolis. All right reserved.
Revision date: 08/18/2011(Michelle Yu)
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
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
A servo is activated by creating an instance of the Servo class passing the desired pin to the attach() method.
The servos are pulsed in the background using the value most recently written using the write() method
Note that analogWrite of PWM on pins associated with the timer are disabled when the first servo is attached.
Timers are seized as needed in groups of 12 servos - 24 servos use two timers, 48 servos will use four.
The sequence used to sieze timers is defined in timers.h
The methods are:
Servo - Class for manipulating servo motors connected to Arduino pins.
attach(pin ) - Attaches a servo motor to an i/o pin.
attach(pin, min, max ) - Attaches to a pin setting min and max values in microseconds
default min is 544, max is 2400
write() - Sets the servo angle in degrees. (invalid angle that is valid as pulse in microseconds is treated as microseconds)
writeMicroseconds() - Sets the servo pulse width in microseconds
read() - Gets the last written servo pulse width as an angle between 0 and 180.
readMicroseconds() - Gets the last written servo pulse width in microseconds. (was read_us() in first release)
attached() - Returns true if there is a servo attached.
detach() - Stops an attached servos from pulsing its i/o pin.
This library has been modified to support the PIC32 architecture.
NOTE: On 09/18/2012 the code to disable a UART on pins 0 and 1 when
assigning a servo to those pins was removed, since not all boards have
UARTs on pins 0 and 1. You must be careful to disable any other function
on a given pin before you start using a servo output on that pin. For
example, if you have the standard UART on pins 1 and 0 and you want to use
those pins for servo output, you would need to disable the UART first.
Version history:
See Servo.cpp
#ifndef Servo_h
#define Servo_h
#ifndef WProgram_h
#include "WProgram.h"
#include <inttypes.h>
#define Servo_VERSION 3 // software version of this library
#define SERVOS_PER_TIMER 8 // the maximum number of servos controlled by one timer
#define MAX_SERVOS 24 // Maximum number of servos this library can support at once
#define MIN_PULSE_WIDTH 544 // the shortest pulse sent to a servo (us)
#define MAX_PULSE_WIDTH 2400 // the longest pulse sent to a servo (us)
#define DEFAULT_PULSE_WIDTH 1500 // default pulse width when servo is attached (us)
#define REFRESH_INTERVAL 20000 // minumim time to refresh servos in microseconds
#define INVALID_SERVO 255 // flag indicating an invalid servo index
typedef struct {
uint8_t nbr :7 ; // a pin number from 0 to 127
uint8_t isActive :1 ; // true if this channel is enabled, pin not pulsed if false
} ServoPin_t ;
typedef struct {
ServoPin_t Pin;
unsigned int ticks;
} servo_t;
class Servo
uint8_t attach(int pin); // attach the given pin to the next free channel, sets pinMode, returns channel number or 0 if failur
uint8_t attach(int pin, int min, int max); // as above but also sets min and max values for writes.
void detach();
void write(int value); // if value is < 200 its treated as an angle, otherwise as pulse width in microseconds
void writeMicroseconds(int value); // Write pulse width in microseconds
int read(); // returns current pulse width as an angle between 0 and 180 degrees
int readMicroseconds(); // returns current pulse width in microseconds for this servo (was read_us() in first release)
bool attached(); // return true if this servo is attached, otherwise false
uint8_t servoIndex; // index into the channel data for this servo
int8_t min; // minimum is this value times 4 added to MIN_PULSE_WIDTH
int8_t max; // maximum is this value times 4 added to MAX_PULSE_WIDTH
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