/**************************************************************************************************
---------------------------------------------------------------------------------------------------
	Copyright (c) 2004-2008, Jonathan Bagg
	All rights reserved.

	 Redistribution and use in source and binary forms, with or without modification, are permitted 
	 provided that the following conditions are met:

    * Redistributions of source code must retain the above copyright notice, this list of 
	  conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright notice, this list of 
	  conditions and the following disclaimer in the documentation and/or other materials provided 
	  with the distribution.
    * Neither the name of Jonathan Bagg nor the names of its contributors may be used to 
	  endorse or promote products derived from this software without specific prior written permission.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR 
  IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY 
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   Project name : Infidigm AVR Drivers
   Processor	: ATMega64, ATMega128
   File name    : pid.h
---------------------------------------------------------------------------------------------------
   Modifications: 

   Revision 1.0  2004/07/23 	Bagg
   - Finished for release
   
   Revision 1.1  2008/04/26 	Bagg
   - Added variable to cap maximum accumulated error
---------------------------------------------------------------------------------------------------
   Created      : 10 April 2004                Author(s) : Jonathan Bagg
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   Pid Controller 
---------------------------------------------------------------------------------------------------
**************************************************************************************************/

/**************************************************************************************************
*   Define PIDFLOAT to make PID have Float gains (Comment out for Char gains)
**************************************************************************************************/
//#define PIDFLOAT

/**************************************************************************************************
*   Structure for PID Variables  (add 'struct pidvars pidMotor1, pidMotor2;' in your application)
**************************************************************************************************/
struct pidvars {
	signed int input;
	signed int output;
	signed int setpoint;
	signed int lasterror;
	signed int limit;
	signed int accumerror;
	signed int max_accum;
	signed int maxout;
	#ifdef PIDFLOAT
	 float pgain;
	 float igain;
	 float dgain;
	#else
	 unsigned char pgain;
	 unsigned char igain;
	 unsigned char dgain;
	#endif
	unsigned char deadband;
 };
 
/**************************************************************************************************
*
*   Function          : pid
*
*   Description       : Proportional Integral Derivative (PID) Controller for Motor Speed Control.
*						This PID Controller is fully "Signed" so 'pidMotor2.setpoint = -75;' will
*						run the motor in reverse and 'pidMotor2.setpoint = 75;' will run the motor
*						forward at 75 pulses/second.
*						Output = Kp*error + Ki*(sum of all errors) + Kd*(lasterror - error)
*
*	Char Gains		  :	When the algorithm is using 'char' gains, it is setup to have a gain from
*						0.0625 to 16.  The gain is = n / 16; where;
*						pgain = 16 would gave Kp = 1
*						pgain = 1 would gave Kp = 1/16 = 0.0625
*						pgain = 255 would gave Kp = 255/16 ~16
*						
*	Execution Time	  : char gains 	= 24 uS
*	  at 15.36 Mhz		float gains = 385 uS
*
*   Parameters        : (&pidMotor2) The Struct that contains the pid variables for the specific motor  
*
*   Functions Called  : None
*
*   Returns           : Calculated output to be passed to motor() function (-1023 to 1023)
*
**************************************************************************************************/
 signed int pid(struct pidvars *piddata);