1-wire protocol project to read temparature

Program to provide 1msec Delay Delay.h

void Delayus(unsigned int);
void Delayms(unsigned int);


void Delayms(unsigned int m)
{
unsigned int i,j;
for(i=0;i<m;i++)
for(j=0;j<1275;j++);
}

DS18b20 Temparature Sensor Ds18b20.h

sbit DQ  =  P3^5; // connect with DS1820 Data pin

void DelayMs(unsigned int);
bit ResetDS1820(void);
void DelayUs(int);
bit ReadBit(void);
void WriteBit(bit);
unsigned char ReadByte(void);
void WriteByte(unsigned char);
int ReadTemp(void);
void Delayus(int);


void DelayUs(int us)
{
 int i;
 for (i=0; i<us; i++);
}


//----------------------------------------
// Reset DS1820
//----------------------------------------
bit ResetDS1820(void)
{
 bit presence;
 DQ = 0;   //pull DQ line low
 DelayUs(29);  // leave it low for about 490us
 DQ = 1;   // allow line to return high
 DelayUs(3);  // wait for presence 55 uS
 presence = DQ;  // get presence signal
 DelayUs(25);  // wait for end of timeslot 316 uS 
 return(presence); // presence signal returned
}  // 0=presence, 1 = no part

//-----------------------------------------
// Read one bit from DS1820
//-----------------------------------------
bit ReadBit(void)
{
 unsigned char i=0;
 DQ = 0;  // pull DQ low to start timeslot
 DQ=1;
 for (i=0; i<3; i++); // delay 17 us from start of timeslot
 return(DQ); // return value of DQ line
}

//-----------------------------------------
// Write one bit to DS1820
//-----------------------------------------
void WriteBit(bit Dbit)
{
 unsigned char i=0; 
    DQ=0; 
 DQ = Dbit ? 1:0;
 DelayUs(5);    // delay about 39 uS
 DQ = 1;
}

//-----------------------------------------
// Read 1 byte from DS1820
//-----------------------------------------
unsigned char ReadByte(void)
{
 unsigned char i;
 unsigned char Din = 0;
 for (i=0;i<8;i++)
 {
  Din|=ReadBit()? 0x01<<i:Din;
  DelayUs(6); 
 }
 return(Din);
}

//-----------------------------------------
// Write 1 byte
//-----------------------------------------
void WriteByte(unsigned char Dout)
{
 unsigned char i;
 for (i=0; i<8; i++) // writes byte, one bit at a time
 {     
  WriteBit((bit)(Dout & 0x1));   // write bit in temp into
  Dout = Dout >> 1;
 }
 DelayUs(5);
}

//-----------------------------------------
// Read temperature
//-----------------------------------------
int ReadTemp(void)
{
 unsigned char n,buff[2];
 int temp;
 
 EA=0; // disable all interrupt
 ResetDS1820();
    WriteByte(0xcc);  // skip ROM
    WriteByte(0x44);  // perform temperature conversion
    while (ReadByte()==0xff); // wait for conversion complete 
    ResetDS1820();
    WriteByte(0xcc);  // skip ROM
    WriteByte(0xbe);  // read the result
    
    for (n=0; n<2; n++)     // read 9 bytes but, use only one byte
    {
       buff[n]=ReadByte();  // read DS1820
    }
 EA=1;
 temp=buff[1];
 temp=temp<<8;
 temp=temp|buff[0];
 return(temp);
}

Program to roll a string on LCD LCD.h

#define lcd P0 //LCD Data lines connected to Port 0
sbit rs=P2^0;  //RS bit connected to Port 2.0
sbit rw=P2^1;  //RW bit connected to Port 2.1
sbit en=P2^2;  //En bit connected to Port 2.2

void init_lcd(void);
void writecmd(unsigned char);
void lcd_char(unsigned char);
void lcd_str(unsigned char*,unsigned char);
void lcd_int(char);
void Delayus(int);

//----------------------------------------
// Initlise LCD
//----------------------------------------
void init_lcd()
{
writecmd(0x38);
writecmd(0x0c);
writecmd(0x06);
writecmd(0x01);
}
//----------------------------------------
// Writing command to LCD
//----------------------------------------
void writecmd(unsigned char c)
{
lcd=c;
rs=rw=0;
en=1;
Delayus(400);
en=0;
}

//----------------------------------------
// Writing Char on LCD
//----------------------------------------
void lcd_char(unsigned char d)
{
lcd=d;
rs=1;
rw=0;
en=1;
Delayus(400);
en=0;
}

//----------------------------------------
// Writing String 
//----------------------------------------
void lcd_str(unsigned char *s,unsigned char l)
{
writecmd(l);
while(*s)
lcd_char(*s++);
}

//----------------------------------------
// Writing Integer
//----------------------------------------
void lcd_int(char i)
{
char d=0,t=0,h=0;
if(i)
{
 d=(i%10)+48;
 i=i/10;
 if(i)
 {
  t=(i%10)+48;
  i=i/10;
  if(i)
  h=i+48;
 }
}
if(h)
lcd_char(h);
if(t)
lcd_char(t);
if(d)
lcd_char(d);
}

Serial Data Transmission Serial.h

void init_serial(void);
void ser_char(unsigned char);
void ser_str(unsigned char *);
void ser_int(char);

//----------------------------------------
// Initlise Serial communication 
//----------------------------------------
void init_serial()
{
TMOD=0x20;
TH1=-3;
SCON=0x40;
}

//----------------------------------------
// Sending Character
//----------------------------------------
void ser_char(unsigned char c)
{
TR1=1;
SBUF=c;
while(!TI);
TR1=0;
TI=0;
}

//----------------------------------------
// Sending String
//----------------------------------------
void ser_str(unsigned char *s)
{
while(*s)
ser_char(*s++);
}

//----------------------------------------
// Sending integer
//----------------------------------------
void ser_int(char i)
{
char d=0,t=0,h=0;
if(i)
{
 d=(i%10)+48;
 i=i/10;
 if(i)
 {
  t=(i%10)+48;
  i=i/10;
  if(i)
  h=i+48;
 }
}
if(h)
ser_char(h);
if(t)
ser_char(t);
if(d)
ser_char(d);
}

Main Program To Calculate Temparature by Using 1-wire Protocol Main.c

#include<reg51.h>
#include"lcd.h"
#include"serial.h"
#include"ds18b20.h"


void Delayms(unsigned int);

main()
{
int temp;
char tp,tpd,n=0;
init_lcd();
init_serial();
lcd_str("Temperature:",0x80);
//ser_str("Temperature: ");
while(1)
 {
 n++;
 temp=ReadTemp();        
 tp  = temp>>4;
 tpd=temp&0x08?0x35:0x30;
 writecmd(0xc0);
 lcd_int(tp);
 lcd_char('.');
 lcd_char(tpd);
 lcd_str(" Degree C",0xc4);
 ser_int(n);
   ser_str(" Temperature= ");
 ser_int(tp);
 ser_char('.');
 ser_char(tpd);
 ser_str(" Degree C\r\n ");
 Delayms(200);
 }
}

void Delayms(unsigned int m)
{
unsigned int i,j;
for(i=0;i<m;i++)
for(j=0;j<1275;j++);
}

Categories: Embedded C, EmbeddedSystems