//Program function: Test the current ambient temperature through DS18B20, and display the current temperature value through the digital tube

#include "reg52.h"

#include

#include //The absolute value function abs() is used

#define uchar unsigned char

#define uint unsigned int

sbit we=P2^7;//Nigital tube bit selection

sbit du=P2^6; //Nigital tube segment selection

sbit dio=P2^5;

sbit ds=P2^2;

int tempValue1;

unsigned int temp;

uchar code th0=(65535-3000)/256;

uchar code tl0=(65535-3000)%256;

uchar dispbuf[6];

uchar code disptab[]={0x3f,0x6,0x5b,0x4f,0x66,

0x6d,0x7d,0x27,0x7f,0x6f,0x77,0x7c,0x39,0x5e,

0x79,0x71,0x0};

uchar code disptabwithdot[]={0xbf,0x86,0xdb,0xcf,0xe6,0xed,0xfd,0xa7,0xff,0xef,0xf7,

0xfc,0xb9,0xf9,0xf1};

uchar code dispbit[]={0xfe,0xfd,0xfb,0xf7,0xef,0xdf};

//Delay function, for 11.0592MHz clock, for example i=10, the delay is about 10ms.

void delay(unsigned int i)

{

unsigned int j;

p>

while(i--)

{

for(j = 0; j < 125; j++);

}

}

void dsInit()

{

//For 11.0592MHz clock, unsigned int type i, the time to perform an i++ operation Greater than ?us

unsigned int i;

ds = 0;

i = 100; //Pull down about 800us, more than 480us in line with the protocol requirements< /p>

while(i>0) i--;

ds = 1; //Generate a rising edge and enter the waiting response state

i = 4;< /p>

while(i>0) i--;

}

void dsWait()

{

unsigned int i;

while(ds);

while(~ds); //Response pulse detected

i = 4;

while(i > 0) i--;

}

//Read one bit of data from DS18B20

//Read one bit, Let DS18B20 be at low level for a short period, and then be at high level for two small periods,

//After that, DS18B20 will output one bit of data for a period of time

bit readBit()< /p>

{

unsigned int i;

bit b;

ds = 0;

i++; // The delay is about 8us, and the delay is at least 1us if it meets the protocol requirements

ds = 1;

i++; i++; //The delay is about 16us, and the delay is at least 15us if it meets the protocol requirements< /p>

b = ds;

i = 8;

while(i>0) i--; //The delay is about 64us, which is consistent with the read time slot. Less than 60us requirement

return b;

}

//Read one byte of data, achieved by calling readBit()

{

unsigned int i;

unsigned char j, dat;

dat = 0;

for(i=0; i<8; i++)

{

j = readBit();

//most The lowest bit of data is read out first

dat = (j << 7) | (dat >> 1);

}

return dat;< /p>

}

//Write one byte of data to DS18B20

void writeByte(unsigned char dat)

{

unsigned int i;

unsigned char j;

bit b;

for(j = 0; j < 8; j++)

{

b = dat & 0x01;

dat >>= 1;

//Write "1", pull DQ low for 15us After that, pull DQ high within 15us~60us to complete writing 1

if(b)

{

ds = 0;

i++; i++; // Pull down about 16us, the symbol must be within 15~60us

ds = 1;

i = 8; while(i>0) i- -; //The delay is about 64us, which meets the requirement of writing time slot not less than 60us

}

else //Write "0", pull DQ low for 60us~120us

ds = 0;

i = 8; while(i>0) i--; // Pull down about 64us, symbol requirements

ds = 1;

i++; i++; //The entire process of writing a 0 time slot has exceeded 60us, so there is no need to delay another 64us like writing a 1

}

}

//Send temperature conversion command to DS18B20

void sendChangeCmd()

{

dsInit(); //Initialization DS18B20, no matter what command, initialization must be initiated first

dsWait(); //Wait for DS18B20 response

delay(1); //Delay 1ms, because DS18B20 will pull low DQ 60~240us as response signal

writeByte(0xcc); //Write skip sequence number command word Skip Rom

writeByte(0x44); //Write temperature conversion command Word Convert T

}

//Send read data command to DS18B20

void sendReadCmd()

{ EA=0; //Turn off interrupts because entering the display interrupt will affect the read and write timing of DS18B20

dsInit();

dsWait();

delay(1) ;

writeByte(0xcc); //Write skip sequence number command word Skip Rom

writeByte(0xbe); //Write read data command word Read Scratchpad

EA=1;

}

//Get the current temperature value

int getTmpValue()

{< /p>

unsigned int tmpvalue;

int value; //Storage temperature value

float t;

unsigned char low, high;

EA=0;

sendReadCmd();

//Continuously read two bytes of data

low = readByte();

high = readByte();

//Combine the high and low bytes into an integer variable

//Computers use complement codes to calculate negative numbers. Represented

//If it is a negative value, the read value is expressed in complement and can be directly assigned to an int value

tmpvalue = high;

tmpvalue <<= 8;

tmpvalue |= low;

value = tmpvalue;

//Use the default resolution of DS18B20, 12 bits, The accuracy is 0.0625 degrees, that is, the lowest bit of the read back data represents 0.0625 degrees

t = value * 0.0625;

//Enlarge it 100 times so that the decimal point can be displayed during display The last two digits, and round the third decimal point by 4 or 5

//For example, t=11.0625, after counting, we get value = 1106, which is 11.06 degrees

// For example, t=-11.0625, after counting, we get value = -1106, which is -11.06 degrees

value = t * 100 + (value > 0 ? 0.5 : -0.5); //If it is greater than 0, add 0.5 , less than 0 minus 0.5

return value;

EA=1;

}

void Init_timer0()

TMOD=0x01;

TH0=th0;

TL0=tl0;

EA=1;

ET0=1;

TR0=1;

}

void timer0() interrupt 1

{ uchar tmp ;

uchar tmp1;

static uchar count;

P0|=0x3f;

we=1;

tmp1=tmp;

P0&=tmp;

we=0;

du =1;

tmp=dispbuf[count];

if(tmp1==0xfb)

{

tmp=disptabwithdot[ tmp];

}

else

{

tmp=disptab[tmp];

}< /p>

P0=tmp;

du=0;

count++;

if(count==6)

{

count=0;

}

//unsigned int temp = abs(tempValue);

dispbuf[0] = temp/ 10000;

dispbuf[1] = temp % 10000 / 1000;

dispbuf[2] =temp % 1000 / 100;

dispbuf[ 3] = temp % 100 / 10;

dispbuf[4] = temp % 10;

TH0=th0;

TL0=tl0;

}

void main()

{ dio=0;

Init_timer0();

/*dispbuf[ 5]=0xf;

dispbuf[4]=0xf;

dispbuf[3]=0xf;

dispbuf[2]=0;

dispbuf[1]=0;

dispbuf[0]=0;*/

while(1)

{

//Start temperature conversion

sendChangeCmd();

tempValue1 = getTmpValue();

temp = abs(tempValue1);

// temp=getTmpValue();

}

}