51单片机实现PID算法（温度控制）

//================================================================
// pid.H
// Operation about PID algorithm procedure
// C51编译器Keil 7.08
//================================================================
// 作者:zhoufeng
// Date :2007-08-06
// All rights reserved.
//================================================================

#include
#include
typedef unsigned char uint8;
typedef unsigned int uint16;
typedef unsigned long int uint32;

void PIDOutput ();
void PIDOperation ();

typedef struct PIDValue
{
uint32 Ek_Uint32[3]; //差值保存，给定和反馈的差值
uint8 EkFlag_Uint8[3]; //符号，1则对应的为负数，0为对应的为正数
uint8 KP_Uint8;
uint8 KI_Uint8;
uint8 KD_Uint8;
uint16 Uk_Uint16; //上一时刻的控制电压
uint16 RK_Uint16; //设定值
uint16 CK_Uint16; //实际值
}PIDValueStr;
PIDValueStr PID;
uint8 out ; // 加热输出
uint8 count; // 输出时间单位计数器

void PIDOperation (void)
{
uint32 Temp[3]; //中间临时变量
uint32 PostSum; //正数和
uint32 NegSum; //负数和
Temp[0] = 0;
Temp[1] = 0;
Temp[2] = 0;
PostSum = 0;
NegSum = 0;
if( PID.RK_Uint16 > PID.CK_Uint16 ) //设定值大于实际值否？
{
if( PID.RK_Uint16 - PID.CK_Uint16 >10 ) //偏差大于10否？
{
PID.Uk_Uint16 = 100; } //偏差大于10为上限幅值输出(全速加热)
else
{
Temp[0] = PID.RK_Uint16 - PID.CK_Uint16; //偏差<=10,计算E(k)
PID.EkFlag_Uint8[1]=0; //E(k)为正数
//数值移位
PID.Ek_Uint32[2] = PID.Ek_Uint32[1];
PID.Ek_Uint32[1] = PID.Ek_Uint32[0];
PID.Ek_Uint32[0] = Temp[0];

if( PID.Ek_Uint32[0] >PID.Ek_Uint32[1] ) //E(k)>E(k-1)否？
{
Temp[0]=PID.Ek_Uint32[0] - PID.Ek_Uint32[1]; //E(k)>E(k-1)
PID.EkFlag_Uint8[0]=0; } //E(k)-E(k-1)为正数
else
{
Temp[0]=PID.Ek_Uint32[0] - PID.Ek_Uint32[1]; //E(k) PID.EkFlag_Uint8[0]=1; } //E(k)-E(k-1)为负数

Temp[2]=PID.Ek_Uint32[1]*2 ; // 2E(k-1)
if( (PID.Ek_Uint32[0] PID.Ek_Uint32[2])>Temp[2] ) //E(k-2) E(k)>2E(k-1)否？
{
Temp[2]=(PID.Ek_Uint32[0] PID.Ek_Uint32[2])-Temp[2]; //E(k-2) E(k)>2E(k-1)
PID.EkFlag_Uint8[2]=0; } //E(k-2) E(k)-2E(k-1)为正数
else
{
Temp[2]=Temp[2]-(PID.Ek_Uint32[0] PID.Ek_Uint32[2]); //E(k-2) E(k)<2E(k-1)
PID.EkFlag_Uint8[2]=1; } //E(k-2) E(k)-2E(k-1)为负数

Temp[0] = (uint32)PID.KP_Uint8 * Temp[0]; // KP*[E(k)-E(k-1)]
Temp[1] = (uint32)PID.KI_Uint8 * PID.Ek_Uint32[0]; // KI*E(k)
Temp[2] = (uint32)PID.KD_Uint8 * Temp[2]; // KD*[E(k-2) E(k)-2E(k-1)]

if(PID.EkFlag_Uint8[0]==0)
PostSum = Temp[0];//正数和
else
NegSum = Temp[0];//负数和

if(PID.EkFlag_Uint8[1]==0)
PostSum = Temp[1];//正数和
else
;//空操作，E(K)>0

if(PID.EkFlag_Uint8[2]==0)
PostSum = Temp[2];//正数和
else
NegSum = Temp[2];//负数和

PostSum = (uint32)PID.Uk_Uint16;

if(PostSum > NegSum )// 是否控制量为正数
{ Temp[0] = PostSum - NegSum;
if( Temp[0] < 100 )//小于上限幅值则为计算值输出
PID.Uk_Uint16 = (uint16)Temp[0];
else
PID.Uk_Uint16 = 100;//否则为上限幅值输出
}
else//控制量输出为负数，则输出0(下限幅值输出)
PID.Uk_Uint16 = 0;
}
}
else
{ PID.Uk_Uint16 = 0;}

}

voidPIDOutput (void)
{
staticint i;
i=PID.Uk_Uint16;
if(i==0)
out=1;
else out=0;
if((count )==5)//如定时中断为40MS,40MS*5=0.2S(输出时间单位),加热周期20S(100等份)
{//每20S PID运算一次
count=0;
i--;
}
}