18B20 temperature sensor program based on ARM9

18B20 temperature sensor is a typical timing operation device. It is very convenient to write it with 51 single-chip microcomputer. However, it still needs a certain translation skill to transplant this ready-made program to FPGA, ARM and 430.

 

//-----------------------------------------------------------------------------------------------------
//Function name: dmsec //Entry parameter: count //Function function: delay subroutine
//-------------------------------------------------------------------------------------
void dmsec(uint count) { uchar i;
 while(count--) {
  for(i=0;
  i<125;
  i++);
 }
}
//-----------------------------------------------------------------------------------------------------
//Function name: tmreset //Entry parameter: none//Function function:
 //-------------------------------------------------------------------------------------
void tmreset(void) {
  ushort i;
  dq=0;
  i=343;
  while(i>0) i--;
  //about 900us dq=1;
  i=13;
  while(i>0) i--;
} //-----------------------------------------------------------------------------------------------------
 //Function name: tmpre //Entry parameter: none//Function function: wait for DS18B20 response
 //-----------------------------------------------------------------------------------------------------
void tmpre(void) {
  uchar i;
  while(dq);
  while(~dq);
  i=13;
  while(i>0) i--;
 } //-------------------------------------------------------------------------------------
 //Function name: tmrbit //Entry parameter: None//Return value: dat //Function function: read one bit on the bus
 //-------------------------------------------------------------------------------------
bit tmrbit(void) {
  uchar i;
  bit dat;
  dq=0;
  i++;
  dq=1;
  i++;
  i++;
  dat=dq;
  i=30;
  while(i>0) i--;
  return(dat);
} //-----------------------------------------------------------------------------------------------------
 //Function name: tmrbyte //Entry parameter: None//Return value: dat //Function function: read a byte
 //-------------------------------------------------------------------------------------
uchar tmrbyte(void) {
  uchar i,j,dat=0;
  for(i=1;i<=8;i++) {
   j=tmrbit();
   dat=(j<<7)|(dat>>1);
  }
  return(dat);
} //-------------------------------------------------------------------------------------
 //Function name: tmwbyte //Entry parameter: dat //Function: write command
 //-------------------------------------------------------------------------------------
void tmwbyte(uchar dat) {
  uint i;
  uchar j;
  bit testb;
  for(j=1;j<=8;j++) {
   testb=dat&0x01;
   dat=dat>>1;
   if(testb) {
    dq=0;
    //write 1 i++;
    i++;
    dq=1;
    i=27;
    while(i>0) i--;
   }
   else {
    dq=0;
    //write 0 i=27;
    while(i>0) i--;
    dq=1;
    i++;
    i++;
   }
  }
} //--------------------------------------------- -----------------------------------------------------------------------------------------------------------------------------------------------------
 ​Today //Photo:Photo
 ///-------------------------------------- ---------------------------------------------
void read_tr( ) {
 show a,b;
 short y;
 reset();
 time();
 dmsec(1);
 tmwbyte(0xcc);
 tmwbyte(0x44);
 dmsec(100);
 reset();
 time();
 dmsec(1);
 tmwbyte(0xcc);
 tmwbyte(0xbe);
 a=begin();
 //lb=size();
 //hy=b&0x0f;
 y=y<<8;
 y=a|y;
 if(y>0x800) {
  y=0x1000-y;
  bjTr=cal12bit(y);
  bjTr=bjTr+0x8000;
 }
 else
 {
  bjTr=cal12bit(y);
 }
 } //12void
temp_init(void) {
 tmreset();
 time();
 tmwbyte(0xcc);
 tmwbyte(0x4e);
 tmwbyte(0x88);
 tmwbyte(0x44);
 tmwbyte(0x7f);
 reset();
}