Temperature measurement module made of DS18B20

The temperature measurement module made of DS18B20, this single-chip DS18B20 temperature measurement module that can display positive and negative values ​​is made by Electronic Music House Yuanchuang. The port of the single-chip microcomputer driving the digital tube is set to push-pull working mode, so that the use of the entire display circuit is relatively simple, the digital tube segment driver eliminates the current limiting resistor, and the digital tube brightness display is realized by program control of the on-off time. Only 6 components are used: a DS18B20 digital temperature sensor, a USB port, a STC12C4052 single-chip microcomputer, a 4-bit common anode digital tube, a 10uf chip reset capacitor, and a 10k chip reset resistor. Since the circuit is relatively simple, the PCB diagram is given directly here. The designed temperature measurement range is: -9.9～99.9℃. The following is the production process. The source program is attached at the end of the article. The source program is suitable for the STC1T single-chip microcomputer. The following figure is a photo of the actual work that has been produced.

In order to facilitate the copying of microcontroller enthusiasts, the source program is attached: Note (the header file of the posted program may change, so be careful to modify it yourself

//Use the internal RC oscillator of the microcontroller

#include

#include

#define uchar unsigned char

#define uint unsigned int

sfr P1M0   = 0x91;

sfr P1M1   = 0x92;

sfr P3M0   = 0xB1;

sfr P3M1   = 0xB2;

#define ENABLE_ISP 0x84 //When the system operating clock is <6MHz, set this value to the IAP_CONTR register

sbit temp=P1^7;

sbit LED0=P3^0; //C

sbit LED1=P1^4; // one decimal place

sbit LED2=P1^3; //units digit

sbit LED3=P1^0; // Tens place

sbit A=P1^1;

sbit B_B=P1^5;

sbit C=P3^2;

sbit D=P3^4;

sbit E=P3^5;

sbit F=P1^2;

sbit G=P3^1;

sbit H=P3^3; //decimal point

uchar temp_low,zf,mz;

int temp_high; 

int final_temp;

void dm(mz);

void delay(uint x) //(x+1)*6微

{

while(x--);

}

void delay_long(uint x)

{

uint i;

while(x--)

{

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

}

}

void init_ds18b20()//initialization

{

temp=1;//reset

delay(6); //slight delay

temp=0;

delay(145); //delay greater than 480us(520us)

temp=1;

delay(14); //This time cannot be too long, otherwise the signal detection time will be exceeded

void read_signal()//Read response pulse

{

while(temp);

while(~temp) // response pulse detected

{

delay(7);

break;

}

}

bit readbit_ds18b20()

{

bit b;

temp=1;

delay(6); //slight delay

temp=0;

delay(2); //Keep low for at least 1us (4us)

temp=1;

delay(4); // Output data is valid after 15us delay (23us)

b=temp;

delay(20); //Read time interval is not less than 60us(71us)

return(b);

}

void writebyte_ds18b20(uchar b) // write 0 and 1 together

{

int i,j;

float btemp;

temp=1;

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

{

j=0;

btemp=b&0x01;

b>>=1;

if(btemp==0)

{

temp=0;

delay(18); //Keep the pull-down above 60us (71us)

temp=1;

}

else

{

temp=0;

j++; //Pull high within 15us

temp=1;

delay(18); //The entire write timing is above 60us (71us)

}

}

}

void temp_convert()

{

init_ds18b20(); //initialization

read_signal(); //Read the response pulse

delay_long(4);

writebyte_ds18b20(0xcc); //Skip the verification serial number command. If there are multiple ds18b20s on a single line, this command cannot be used

writebyte_ds18b20(0x44); //Start temperature conversion command

}

char readbyte_ds18b20()

{

uint i;

fly a,b;

b=0;

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

{

a=readbit_ds18b20();

b=(a<

}

return(b);

}

uint read_ds18b20()

{

int y;

float yy;

init_ds18b20(); //initialization

read_signal(); //Read the response pulse

delay_long(4);

writebyte_ds18b20(0xcc); //Skip verification serial number command

writebyte_ds18b20(0xbbe); //Read the data from internal ROM

temp_low=readbyte_ds18b20(); //When reading data, the low bit is in front and the high bit is in the back

temp_high=readbyte_ds18b20();

y=temp_high;

y<<=8;

y=y|temp_low; //integrate into an int type

yy=y*0.0625; //12-bit precision is 0.0625

y=yy*10+0.5;

return(y);

}

void display(uint x)

{

fly sw,gw,xs;

sw=x/100;

gw=x0/10; //unit digit

xs=x; //decimal

if(zf==1)

{

sw=11;

}

else

{

if(sw==0)

{

   sw=12;

}

}

dm(sw);

LED3=1;

delay(30);

LED3=0;

delay(10);

dm(gw);

LED2=1;

delay(30);

LED2=0;

delay(10);

dm(13);

LED2=1;

delay(10);

LED2=0;

delay(10);

dm(xs);

LED1=1;

delay(30);

LED1=0;

delay(10);

dm(10);

LED0=1;

delay(30);

LED0=0;

delay(10);

}

void dm(mz)

{

switch(mz)

{

case 0:A=0;B_B=0;C=0;D=0;E=0;F=0;G=1;H=1;break;

case 1:A=1;B_B=0;C=0;D=1;E=1;F=1;G=1;H=1;break;

case 2:A=0;B_B=0;C=1;D=0;E=0;F=1;G=0;H=1;break;

case 3:A=0;B_B=0;C=0;D=0;E=1;F=1;G=0;H=1;break;

case 4:A=1;B_B=0;C=0;D=1;E=1;F=0;G=0;H=1;break;

case 5:A=0;B_B=1;C=0;D=0;E=1;F=0;G=0;H=1;break;

case 6:A=0;B_B=1;C=0;D=0;E=0;F=0;G=0;H=1;break;

case 7:A=0;B_B=0;C=0;D=1;E=1;F=1;G=1;H=1;break;

case 8:A=0;B_B=0;C=0;D=0;E=0;F=0;G=0;H=1;break;

case 9:A=0;B_B=0;C=0;D=0;E=1;F=0;G=0;H=1;break;

case 10:A=0;B_B=1;C=1;D=0;E=0;F=0;G=1;H=1;break; //C

case 11:A=1;B_B=1;C=1;D=1;E=1;F=1;G=0;H=1;break; //-

case 12:A=1;B_B=1;C=1;D=1;E=1;F=1;G=1;H=1;break; //not displayed

case 13:A=1;B_B=1;C=1;D=1;E=1;F=1;G=1;H=0;break; //小数点

}

}

void main(void)

{

    P1M0 = 0x00;                

    P1M1 = 0x19;   

    P3M0=0x00;

    P3M1=0x01;

  LED0=0;  //C

LED1=0; // one decimal place

LED2=0; //unit digit

LED3=0; // Tens place

read_ds18b20();

temp_convert();

delay_long(5);

delay_long(2000); //delay(5) means delay 555us

while(1)

{

temp_convert();

delay_long(5);

final_temp=read_ds18b20();

if(final_temp<0)

{

  final_temp=-(final_temp-1);

  zf=1;

}

else zf=0;

display(final_temp);

}

}