Skip to content
Branch: master
Find file Copy path
Find file Copy path
4 contributors

Users who have contributed to this file

@cmaglie @facchinm @alfran @Fede85
123 lines (101 sloc) 5.13 KB
Servo.h - Interrupt driven Servo library for Arduino using 16 bit timers- Version 2
Copyright (c) 2009 Michael Margolis. All right reserved.
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.
#ifndef Servo_h
#define Servo_h
#include <inttypes.h>
* Defines for 16 bit timers used with Servo library
* If _useTimerX is defined then TimerX is a 16 bit timer on the current board
* timer16_Sequence_t enumerates the sequence that the timers should be allocated
* _Nbr_16timers indicates how many 16 bit timers are available.
// Architecture specific include
#if defined(ARDUINO_ARCH_AVR)
#include "avr/ServoTimers.h"
#elif defined(ARDUINO_ARCH_SAM)
#include "sam/ServoTimers.h"
#elif defined(ARDUINO_ARCH_SAMD)
#include "samd/ServoTimers.h"
#elif defined(ARDUINO_ARCH_STM32F4)
#include "stm32f4/ServoTimers.h"
#elif defined(ARDUINO_ARCH_NRF52)
#include "nrf52/ServoTimers.h"
#include "megaavr/ServoTimers.h"
#elif defined(ARDUINO_ARCH_MBED)
#include "mbed/ServoTimers.h"
#error "This library only supports boards with an AVR, SAM, SAMD, NRF52 or STM32F4 processor."
#define Servo_VERSION 2 // software version of this library
#define MIN_PULSE_WIDTH 544 // the shortest pulse sent to a servo
#define MAX_PULSE_WIDTH 2400 // the longest pulse sent to a servo
#define DEFAULT_PULSE_WIDTH 1500 // default pulse width when servo is attached
#define REFRESH_INTERVAL 20000 // minumim time to refresh servos in microseconds
#define SERVOS_PER_TIMER 12 // the maximum number of servos controlled by one timer
#define MAX_SERVOS (_Nbr_16timers * SERVOS_PER_TIMER)
#define INVALID_SERVO 255 // flag indicating an invalid servo index
#if !defined(ARDUINO_ARCH_STM32F4)
typedef struct {
uint8_t nbr :6 ; // a pin number from 0 to 63
uint8_t isActive :1 ; // true if this channel is enabled, pin not pulsed if false
} ServoPin_t ;
typedef struct {
ServoPin_t Pin;
volatile 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 failure
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
You can’t perform that action at this time.