ServoExt.h

/* Interrupt driven Servo library for Arduino using 16 bit timers - Version 2.
 * This version is extended to support LineDriver interface which allows your hardware
 * to be controlled not only through Arduino pins, but also through shift registers,
 * I2C I/O extenders, or any other I/O bus for which you can implement the LineDriver interface.
 * 
 * Copyright (C) 2009 Michael Margolis
 * Copyright (C) 2011 Artem Borisovskiy (bytefu@gmail.com), http://robocraft.ru
 * 
 * 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
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * 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 SERVOEXT_H_
#define SERVOEXT_H_

#include <inttypes.h>
#include <LineDriver.h>

class Servo
{
public:
  Servo(LineDriver *line_driver = 0);
  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

private:
  LineDriver *pins;
  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   
};

#endif // SERVOEXT_H_