PIC microcontroller temperature sensor DS18B20 C language program code

/*This temperature sensor
is written by myself, the timing has been corrected, and the self-test delay time
uses the Tianxiang temperature conversion module algorithm
*/

#include

__CONFIG(0x3B31);

#define uint unsigned int

#define uchar unsigned char

#define DQ RC1

#define DQ_DIR TRISC1

#define DQ_HIGH() TRISC1=1

#define DQ_LOW() DQ=0;TRISC1=0

unsigned char shi; // tens digit

unsigned char ge; // integer digit

unsigned char shifen; //tenths place

unsigned char baifen; //percentile

unsigned char qianfen; //thousandths

unsigned char wanfen; //ten thousandth place

const uchar table[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f}; //Display array 0

void delayus(char x,char y) //us level delay provided by Huijing

{

char z; //define Z

do { //Execute do once first

  z=y; //Give the value of Y to Z

  do{;}while(--z); //do empty statement, wait for --z, until z=0 ends, do--while statement, delay occurs here

  }     

while (--x); //Similarly, x is in--, and a delay is generated again

}

void delay(uint x)

{

uint a,b;

for(a=x;a>0;a--)

for(b=110;b>0;b--);

}

void display(char shi,char ge,char shifen,char baifen,char qianfen)

{

PORTD=table[shi];

PORTA=0x02;

delay(2);

PORTD=table[ge]|0x80; //or 0x80 to display the decimal point

PORTA=0x04;

delay(2);

PORTD=table[shifen];

PORTA=0x06;

delay(2);

PORTD=table[baifen];

PORTA=0x08;

delay(2);

PORTD=table[qianfen];

PORTA=0x0a;

delay(2);

}

void init(void)

{

TRISA=0;PORTA=0x00;

TRISC=0xf0;PORTC=1;

TRISD=0;

}

void reset(void)

{

char pe=1;

while(pe)

{

DQ_LOW();

delayus(2,81); //delay 502us

DQ_HIGH();

delayus(4,4); //delay 71us

if(DQ==1)pe=1; //Judge whether to respond (pull to low level when responding), set to 1 and resend in a loop if no response

else pe=0; //Otherwise it is a response, set to 0 to exit the loop

delayus(2,81); //delay 502us

}

}

void write_byte(char val)

{

uchar i,temp;

for(i=8;i>0;i--) //Loop 8 times to form a byte

{

temp=val&0x01; //Take out the lowest bit, and take out 1

DQ_LOW();

delayus(1,1); //delay 15us

if(temp==1)DQ_HIGH(); //If the value taken out is 1, pull it to high level and send it out

delayus(3,3); //Delay 45us, if the taken out is 0, also send it

DQ_HIGH(); //Pull up to high level

NOP();NOP(); //Delay 2us

val=val>>1; //Move right once for next extraction

}

}

uchar read_byte(void)

{

uchar i,val=0;

static bit j; //static bit variable, a status bit, cannot be a byte

for(i=8;i>0;i--)

{

val=val>>1; //Move one position first

DQ_LOW(); //Pull to low level

NOP();NOP();NOP();NOP();NOP();NOP(); //Delay 6us

DQ_HIGH();   

NOP();NOP();NOP();NOP(); //Delay 4us

j=DQ; //Read the state of the data line to get a state bit for data processing //So we need to define static bit j;

if(j==1)val=val|0x80; //Data processing: If the value read is 1, put it in the highest bit first, and then shift it back one by one to form a byte

delayus(1,6); //Delay 30us to repeat the above steps

}

return(val); //Construct 1 byte and return

}

void get_temp(void) //01:40:26 //Get temperature, device matching (multiple temperature sensors)

{

uchar TLV,THV,num; //tem1/tem2; there are also 2 bytes of temperature instructions

float aaa;

uint temper;

reset(); //Reset

write_byte(0xCC); //skip ROM

write_byte(0x44); //Temperature conversion, delay required

for(num=100;num>0;num--) //Originally, delay(1000) was used to delay the time for 1 second. But the effect disappears after a short shake.

  display(shi,ge,shifen,baifen,qianfen); //So use the display to replace the delay, display 100 times is about 750ms or more

reset(); //Before each RAM operation, reset 18B20 and match

write_byte(0xCC); //skip ROM

write_byte(0xBE); //Tell it that I will read your temperature next, read the register

TLV=read_byte(); //RAM has 9 bytes (we only need 2 bytes, LSB and MSB), it reads from the lowest bit

THV=read_byte(); //01:45:10 + Ruizhi at 58:52

DQ_HIGH(); //Release the bus

aaa=(THV*256+TLV)*0.0625*1000; //(16-bit temperature data)*0.0625 is the actual temperature (decimal number)

temper=(int)aaa; //Because of the compile-time warning; there is a decimal point, it is a floating point to integer conversion; we use forced conversion to integer to get the value of the decimal point (the decimal point is not easy to get, use multiplication by 100 to get it)

shi=temper/10000; //Distribute the tens to five digital tubes. It feels weird to display four digits, so use five digital tubes; at 1:51:00

ge=temper%10000/1000; //I want to use five digital tubes to display, so it is 10000 five-digit number

shifen=temper%1000/100; //

baifen=temper%100/10; //

qianfen=temper%10; // 

}

void main()

{

init();

while(1)

{

get_temp();

display(shi,ge,shifen,baifen,qianfen); //The compiler will not pass without formal parameters, and it will not pass with class parameters either

}

}