/*!
 *     COPYRIGHT NOTICE
 *     Copyright (c) 2016，晨旭
 *     All rights reserved.
 *     技术讨论：晨旭的博客 http://www.chenxublog.com
 *
 *     除注明出处外，以下所有内容版权均属晨旭所有，未经允许，不得用于商业用途，
 *     修改内容时必须保留晨旭的版权声明。
 *
 * @file       pid.c
 * @brief      PID
 * @author     晨旭
 * @version    v1.0
 * @date       2016-3-7
 */
#include"include.h"

//struct _pid	warm;
//int		process_point, set_point, dead_band;
//float		p_gain, i_gain, d_gain, integral_val, new_integ;

/*
struct _pid    warm;
int process_point  = 30,
    set_point      = 40,
    dead_band      = 2;
float p_gain       = 5.2,
      i_gain       = 0.77,
      d_gain       = 0.18,
      integral_val = 0.01,
      new_integ;




scanf( "%d", &process_point );// 设定PV,SP值

pid_init( &warm, process_point, set_point );// 初始化PID参数值

//PV - 实际的测量值
//SV - 设定的目标值
//SP - 输出的阀开度值（常用 % 表示）

pid_tune( &warm, p_gain, i_gain, d_gain, dead_band, integral_val );// 初始化PID输出值

pid_setinteg( &warm, 0.0 );// Get input value for process point

pid_bumpless( &warm );// how to display output

printf( "%f\n", pid_calc( &warm ) );
*/



/*－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－
*  pid_init DESCRIPTION This function initializes the pointers in the _pid structure to the process variable and the setpoint. *pv and *sp are integer pointers.
*  －－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－*/
void pid_init( struct _pid *warm, int process_point, int set_point )
{
	struct _pid *pid;
	pid	= warm;
	pid->pv = process_point;
	pid->sp = set_point;
}


/*－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－
 * pid_tune DESCRIPTION Sets the proportional gain (p_gain), integral gain (i_gain),
 * derivitive gain (d_gain), and the dead band (dead_band) of a pid control structure _pid.
 *
 * 设定PID参数 －－－－ P,I,D,死区
 * //－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－*/
void pid_tune( struct _pid *pid, float p_gain, float i_gain, float d_gain, int dead_band ,float integral_val )
{
	pid->pgain	= p_gain;
	pid->igain	= i_gain;
	pid->dgain	= d_gain;
	pid->deadband	= dead_band;
	pid->integral	= integral_val;
	pid->last_error = 0;
}


/*－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－
 * pid_setinteg DESCRIPTION Set a new value for the integral term of the pid equation.
 * This is useful for setting the initial output of the pid controller at start up.
 *
 * 设定输出初始值
 * //－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－*/

void pid_setinteg( struct _pid *pid, float new_integ )
{
	pid->integral	= new_integ;
	pid->last_error = 0;
}


/*－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－
 * pid_bumpless DESCRIPTION Bumpless transfer algorithim.
 * When suddenly changing setpoints, or when restarting the PID equation after an extended pause,
 * the derivative of the equation can cause a bump in the controller output. This function will help smooth out that bump.
 * The process value in *pv should be the updated just before this function is used.
 *
 * pid_bumpless 实现无扰切换
 * 当突然改变设定值时，或重新启动后，将引起扰动输出。这个函数将能实现平顺扰动，在调用该函数之前需要先更新PV值
 * //－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－*/

void pid_bumpless( struct _pid *pid )
{
	pid->last_error = (pid->sp) - (pid->pv); /* 设定值与反馈值偏差 */
}


/*－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－
 * pid_calc DESCRIPTION Performs PID calculations for the _pid structure *a.
 * This function uses the positional form of the pid equation, and incorporates an integral windup prevention algorithim.
 * Rectangular integration is used, so this function must be repeated on a consistent time basis for accurate control.
 * RETURN VALUE The new output value for the pid loop. USAGE #include "control.h"
 * 本函数使用位置式PID计算方式，并且采取了积分饱和限制运算
 * PID计算
 * //－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－*/

float pid_calc( struct _pid *pid )
{
	int	err;
	float	pterm, dterm, result, ferror;

/* 计算偏差 */
	err = (pid->sp) - (pid->pv);

/* 判断是否大于死区 */
	if ( abs( err ) > pid->deadband )
	{
		ferror = (float) err; /* do integer to float conversion only once 数据类型转换 */

/* 比例项 */
		pterm = pid->pgain * ferror;

		if ( pterm > 100 || pterm < -100 )
		{
			pid->integral = 0.0;
		}else  {
/* 积分项 */
			pid->integral += pid->igain * ferror;

/*
 * 输出为0－－100%
 * 如果计算结果大于100，则等于100
 */
			if ( pid->integral > 100.0 )
			{
				pid->integral = 100.0;
			}
/* 如果计算结果小于0.0，则等于0 */
			else if ( pid->integral < 0.0 )
				pid->integral = 0.0;
		}

/* 微分项 */
		dterm = ( (float) (err - pid->last_error) ) * pid->dgain;

		result = pterm + pid->integral + dterm;
	}else
		result = pid->integral;  /* 在死区范围内，保持现有输出 */

/* 保存上次偏差 */
	pid->last_error = err;

/* 输出PID值(0-100) */
	return(result);
}


/*
void main( void )
{
	float	display_value;
	int	count = 0;

//
// printf("Enter the values of Process point, Set point, P gain, I gain, D gain \n");
// scanf("%d%d%f%f%f", &process_point, &set_point, &p_gain, &i_gain, &d_gain);
//

// 初始化参数
	process_point	= 30;
	set_point	= 40;
	p_gain		= (float) (5.2);
	i_gain		= (float) (0.77);
	d_gain		= (float) (0.18);
	dead_band	= 2;

	integral_val = (float) (0.01);

	printf( "The values of Process point, Set point, P gain, I gain, D gain \n" );
	printf( " %6d %6d %4f %4f %4f\n", process_point, set_point, p_gain, i_gain, d_gain );
	printf( "Enter the values of Process point\n" );
	while ( count <= 20 )
	{
		scanf( "%d", &process_point );

// 设定PV,SP值
		pid_init( &warm, process_point, set_point );

// 初始化PID参数值
		pid_tune( &warm, p_gain, i_gain, d_gain, dead_band, integral_val );

// 初始化PID输出值
		pid_setinteg( &warm, 0.0 );
// pid_setinteg(&warm,30.0);

// Get input value for process point
		pid_bumpless( &warm );

// how to display output
		display_value = pid_calc( &warm );

		printf( "%f\n", display_value );
// printf("\n%f%f%f%f",warm.pv,warm.sp,warm.igain,warm.dgain);

		count++;
	}
}
*/