51 single chip microcomputer-temperature PID algorithm (C program)

#include "reg51.h"

#include "intrins.h"

#include "math.h"

#include "string.h"

struct PID 

{ 

unsigned int SetPoint; // Set the desired value 

unsigned int Proportion; // Proportional Const 

unsigned int Integral; // Integral Const 

unsigned int Derivative; // differential constant Derivative Const 

unsigned int LastError; // Error[-1] 

unsigned int PrevError; // Error[-2] 

unsigned int SumError; // Sums of Errors 

}; 

struct PID spid; // PID Control Structure 

unsigned int rout; //PID Response (Output) 

unsigned int rin; // PID Feedback (Input) 

sbit data1=P1^0; 

sbit clk=P1^1; 

sbit plus=P2^0; 

sbit subs=P2^1; 

sbit stop=P2^2; 

sbit output=P3^4; 

sbit DQ=P3^3; 

unsigned char flag, flag_1 = 0; 

unsigned char high_time,low_time,count=0; //duty cycle adjustment parameters 

unsigned char set_temper=25; 

unsigned char temper; 

unsigned char i; 

unsigned char j=0; 

unsigned int s; 

void delay(unsigned char time) 

{ 

unsigned char m,n; 

for(n=0;n

for(m=0;m<2;m++){} 

} 

void write_bit(unsigned char bitval) 

{ 

EA=0; 

DQ=0;  

if(bitval==1) 

{ 

_nop_(); 

DQ=1;  

} 

delay(5);  

DQ=1;  

_nop_(); 

_nop_(); 

EA=1; 

} 

void write_byte(unsigned char val) 

{ 

unsigned char i; 

unsigned char temp; 

EA=0; 

TR0=0; 

for(i=0;i<8;i++)  

{ 

temp=val>>i;  

temp=temp&1; 

write_bit(temp);  

} 

delay(7);  

//TR0=1; 

EA=1; 

} 

unsigned char read_bit() 

{ 

unsigned char i,value_bit; 

EA=0; 

DQ=0;  

_nop_(); 

_nop_(); 

DQ=1;  

for(i=0;i<2;i++){} 

value_bit=DQ; 

EA=1; 

return(value_bit); 

} 

unsigned char read_byte() 

{ 

unsigned char i,value=0; 

EA=0; 

for(i=0;i<8;i++) 

{ 

if(read_bit())  

value|=0x01<delay(4);  

} 

EA=1; 

return(value); 

} 

unsigned char reset() 

{ 

unsigned char presence; 

EA=0; 

DQ=0;  

delay(30);  

DQ=1;  

delay(3); 

presence=DQ;  

delay(28);  

EA=1; 

return(presence);  

} 

void get_temper() 

{ 

unsigned char i,j; 

do 

{ 

i=reset();  

} while(i!=0);  

i=0xcc;  

write_byte(i); 

i=0x44;  

write_byte(i); 

delay(180);  

do 

{ 

i=reset();  

} while(i!=0); 

i=0xcc;  

write_byte(i); 

i=0xbe;  

write_byte(i); 

j=read_byte(); 

i=read_byte(); 

i=(i<<4)&0x7f; 

s=(unsigned int)(j&0x0f); //Get the decimal part 

s=(s*100)/16; 

j=j>>4; 

temper=i|j;  

} 

void PIDInit (struct PID *pp) 

{ 

memset ( pp,0,sizeof(struct PID)); // initialize all to 0 

} 

unsigned int PIDCalc(struct PID *pp, unsigned int NextPoint) 

{ 

unsigned int dError,Error; 

Error = pp->SetPoint - NextPoint; // Deviation 

pp->SumError += Error; // integral 

dError = pp->LastError - pp->PrevError; // Current differential 

pp->PrevError = pp->LastError; 

pp->LastError = Error; 

return (pp->Proportion * Error // Proportional term 

+ pp->Integral * pp->SumError // Integral term 

+ pp->Derivative * dError); // differential term 

} 

void compare_temper() 

{ 

unsigned char i; 

if(set_temper>temper) //Is the set temperature greater than the actual temperature? 

{ 

if(set_temper-temper>1) // Is the set temperature greater than the actual temperature by 1 degree? 

{ 

high_time=100; //If yes, heat at full speed 

low_time=0; 

} 

else //If it is within 1 degree, run PID calculation 

{ 

for(i=0;i<10;i++) 

{ 

get_temper(); //Get temperature 

rin = s; // Read Input 

rout = PIDCalc ( &spid,rin ); // Perform PID Interation 

} 

if (high_time<=100) 

high_time=(unsigned char)(rout/800); 

else 

high_time=100; 

low_time = (100-high_time); 

} 

} 

else if (set_temper<=temper) 

{ 

if(temper-set_temper>0) 

{ 

high_time=0; 

low_time=100; 

} 

else 

{ 

for(i=0;i<10;i++) 

{ 

get_temper(); 

rin = s; // Read Input 

rout = PIDCalc ( &spid,rin ); // Perform PID Interation 

} 

if (high_time<100) 

high_time=(unsigned char)(rout/10000); 

else 

high_time=0; 

low_time = (100-high_time); 

} 

} 

// else 

// {} 

} 

void serve_T0() interrupt 1 using 1 

{ 

if(++count<=(high_time)) 

output=1; 

else if(count<=100) 

{ 

output=0; 

} 

else 

count=0; 

TH0=0x2f; 

TL0=0xe0; 

} 

void serve_sio() interrupt 4 using 2 

{ 

} 

void disp_1(unsigned char disp_num1[6]) 

{ 

unsigned char n,a,m; 

for(n=0;n<6;n++) 

{ 

// k=disp_num1[n]; 

for(a=0;a<8;a++) 

{ 

clk=0; 

m=(disp_num1[n]&1); 

disp_num1[n]=disp_num1[n]>>1; 

if(m==1) 

data1=1; 

else 

data1=0; 

_nop_(); 

clk=1; 

_nop_(); 

} 

} 

} 

void display() 

{ 

unsigned char code number[]={0xfc,0x60,0xda,0xf2,0x66,0xb6,0xbe,0xe0,0xfe,0xf6}; 

unsigned char disp_num[6]; 

unsigned int k,k1; 

k=high_time; 

k=k00; 

k1=k/100; 

if(k1==0) 

disp_num[0]=0; 

else 

disp_num[0]=0x60; 

k=k0; 

disp_num[1]=number[k/10]; 

disp_num[2]=number[k]; 

k=temper; 

k=k0; 

disp_num[3]=number[k/10]; 

disp_num[4]=number[k]+1; 

disp_num[5]=number[s/10]; 

disp_1(disp_num); 

} 

void main() 

{ 

unsigned char z; 

unsigned char a,b,flag_2=1,count1=0; 

unsigned char phil[]={2,0xce,0x6e,0x60,0x1c,2}; 

TMOD=0x21; 

TH0=0x2f; 

TL0=0x40; 

SCON=0x50; 

PCON=0x00; 

TH1=0xfd; 

TL1=0xfd; 

PS=1; 

EA=1; 

EX1=0; 

ET0=1; 

ES=1; 

TR0=1; 

TR1=1; 

high_time=50; 

low_time=50; 

PIDInit ( &spid ); // Initialize Structure 

spid.Proportion = 10; // Set PID Coefficients Proportional Const 

spid.Integral = 8; //Integral constant Integral Const 

spid.Derivative =6; //Derivative constant Derivative Const 

spid.SetPoint = 100; // Set PID Setpoint Set the desired value 

while(1) 

{ 

if(plus==0) 

{ 

EA=0; 

for(a=0;a<5;a++) 

for(b=0;b<102;b++){} 

if(plus==0) 

{ 

set_temper++; 

flag=0; 

} 

} 

else if(subs==0) 

{ 

for(a=0;a<5;a++) 

for(b=0;a<102;b++){} 

if(subs==0) 

{ 

set_temper--; 

flag=0; 

} 

} 

else if(stop==0) 

{ 

for(a=0;a<5;a++) 

for(b=0;b<102;b++){} 

if(stop==0) 

{ 

flag=0; 

break; 

} 

EA=1; 

} 

get_temper(); 

b=temper; 

if(flag_2==1) 

a=b; 

if((abs(ab))>5) 

temper=a; 

else 

temper=b; 

a=temper; 

flag_2=0; 

if(++count1>30) 

{ 

display(); 

count1=0; 

} 

compare_temper(); 

} 

TR0=0; 

z=1; 

while(1) 

{ 

EA=0; 

if(stop==0) 

{ 

for(a=0;a<5;a++) 

for(b=0;b<102;b++){} 

if(stop==0) 

disp_1(phil); 

// break; 

} 

EA=1; 

} 

}