Programming based on single chip microcomputer application AVR 18B20

#include //Includes model header file #include //Includes "bit" operation header file #include //Standard input and output header file #include //Includes custom constant header file #include "SMG.C" //Includes digital tube display function /********************************************

#include//Include model header file

#include //Include "bit" operation header file

#include //Standard input and output header files

#include《AVR_PQ1A.h》//Includes custom constant header file

#include "SMG.C" //Includes digital tube display function

/*******************************************

Function name: B20_init

Function: Reset DS18B20

Parameters: None

Return value: None

/************************************************/

void B20_init(void)

{

DDRA|=BIT(DS18B20); //Configure as output

PORTA|=BIT(DS18B20);

Delayus (10);

PORTA&=~BIT(DS18B20); //pull low

Delayus(750); //Wait for 600 microseconds

PORTA|=BIT(DS18B20); //Release the bus

Delayus(60); //Wait for 60 microseconds

DDRA&=~BIT(DS18B20); //Configure as input

while(( PI NA & (BIT(DS18B20)))); //Wait for DS18B20 to pull low

while(!(PINA&(BIT(DS18B20)))); //Wait for DS18B20 to release the bus

}

/*******************************************

Function name: B20_readB

Function: Read one byte of data

Parameters: None

Return value: retd - one byte of data returned

/************************************************/

ucharB20_readB(void)

{

uchari,retd=0;

for (i = 0; i < 8; i ++) // bit count value

{

retd》》=1; //Shift right, ready to receive new data bits

DDRA|=BIT(DS18B20); //Configure as output

PORTA&=~BIT(DS18B20); //Pull low to start reading data bit

PORTA|=BIT(DS18B20); //Release the bus

Delayus(5); //Wait for 5 microseconds

DDRA&=~BIT(DS18B20); //Configure as input, start reading data bits

if (PINA & BIT (DS18B20)) // Is the bit high?

{

retd|=0x80; //Yes, set this position high

}

Delayus(50); //Wait for 50 microseconds

}

returnretd; //Return the read byte

}

/*******************************************

Function name: B20_write B

Function: Write one byte of data

Parameter: wrd--data to be written

Return value: None

/************************************************/

void B20_writeB(ucharwrd)

{

uchari;

for (i = 0; i < 8; i ++) // bit count value

{

DDRA|=BIT(DS18B20); //Configure as output

PORTA&=~BIT(DS18B20); //Pull low to start writing data bit

Delayus(1); //Wait for 1 microsecond

if (wrd & 0x01) // Is this bit data high?

{

PORTA|=BIT（DS18B20）; //If it is high, pull the single bus high

}

else

{

PORTA&=~BIT(DS18B20); //If it is low, pull the single bus low

}

Delayus(50); //Wait for 50 microseconds

PORTA|=BIT(DS18B20); //Release the bus

wrd》》=1; //Shift right to prepare for writing new data bits

}

Delayus(50); //Wait for 50 microseconds

}

/*******************************************

Function Name: Read_temp

Function: Read temperature value

Parameters: None

Return value: rettemp--returned temperature value

/************************************************/

uintRead_temp(void)

{

uchartempl,temph;

uinttemp;

B20_init(); // Initialization, each write command starts from initialization

B20_writeB(0xCC); //skip ROM

B20_writeB(0x44); //Start temperature conversion

B20_init(); // Initialization, each write command starts from initialization

B20_writeB(0xcc); //skip ROM

B20_writeB(0xbe); //read register

templ=B20_readB(); //read temperature low byte

temph=B20_readB(); //read temperature high byte

temp=templ+temph*256; //Organize the temperature into a 16-bit variable

returntemp; //Return 16-bit variable

}

/*******************************************

Function name: Num_BCD

Function: Convert a one-byte integer into a three-digit BCD code

Parameter: num - the integer to be converted

Return value: chr - three-digit BCD code array pointer

/************************************************/

uchar* Num_BCD(uint num)

{

uchari,chr［3］;

uchar*rept;

rept=&(chr［0］); //Return pointer to BCD code array

for (i=0;i<3;i++)

{

chr［2-i］=num%10; //Remainder of 10 (actually modulus, but for positive numbers, remainder and modulus are equal)

num/=10; // Divide by 10 to prepare for taking out the next digit

}

returnrept; //Return pointer

}

/*******************************************

Function name : main

Function: Complete temperature reading and display

Parameters: None

Return value: None

/************************************************/

voi dma in (void)

{

uintt;

uchar*temppt;

uchari, temp［3］;

Board_init(); //Initialize the development board

while(1)

{

t=Read_temp(); //Read temperature value

t*=0.625; //Convert to 10 times the actual temperature

while(t==850)

{

t=Read_temp(); //Read temperature value

t*=0.625;

}

temppt=Num_BCD(t); //Convert 10 times the actual temperature into BCD code

for (i=0;i<3;i++) //Store the converted BCD code in the display array

{

temp［i］=*（temppt+i）;

}

for (i = 0; i < 3; i++) // display temperature

{

if (i == 1)

{

temp［1］+=16; //If it is the same as the digits, add a decimal point (the decoding array of the digital tube has changed, the reader can see the SMG.C file in the 10_DS18B20 folder)

}

One_smg_display(temp［i］，i+1);

Delayms(5);

}

}

}