單片機(jī)高效率代碼讀取18B20 顯示在LCD1602上

ID:529657 · 發(fā)表于 2020-8-5 21:02

#include <STC89C5xRC.H>
#include <intrins.h>

sbit DATA_IO = P3^2;

/* 軟件延時(shí)函數(shù)，延時(shí)時(shí)間(t*10)us */
void DelayX10us(unsigned char t)
{
do {
      _nop_();
      _nop_();
      _nop_();
      _nop_();
      _nop_();
      _nop_();
      _nop_();
      _nop_();
} while (--t);
}

bit GetACK()
{
      bit ack;
      EA = 0;
      DATA_IO = 0;
      DelayX10us(60);
      DATA_IO = 1;
      DelayX10us(6);
      ack = DATA_IO;
      while(!DATA_IO);
      EA = 1;
      return ack;
}

void DS18B20_Write(unsigned char dat)
{
      unsigned char mask;
      EA = 0;
      for(mask=0x01;mask!=0;mask<<=1)
      {
            DATA_IO = 0;
            _nop_();
            _nop_();
            if((dat&mask)!= 0)
                     DATA_IO = 1;
            else
                     DATA_IO = 0;
            DelayX10us(6);
            DATA_IO = 1;
      }
      EA = 1;
}
unsigned char DS18B20_Read()
{
      unsigned char dat;
      unsigned char mask;
      EA = 0;
      for(mask=0x01;mask!=0;mask<<=1)
      {
            DATA_IO = 0;
            _nop_();
            _nop_();
            DATA_IO = 1;
            _nop_();
            _nop_();
            if(!DATA_IO)
                     dat &= ~(mask);
            else
                     dat |= mask;
            DelayX10us(6);
      }
      EA = 1;
      return dat;
}

bit DS18B20_Start()
{
      bit ack;
      ack = GetACK();
      if(ack == 0)
      {
            DS18B20_Write(0xCC);
            DS18B20_Write(0x44);
      }
      return ~ack;
}

bit GetTemp(int *temp)
{
      bit ack;
      unsigned char LSB,MSB;
      ack = GetACK();
      if(ack==0)
      {
            DS18B20_Write(0xCC);
            DS18B20_Write(0xBE);
            LSB = DS18B20_Read();
            MSB = DS18B20_Read();
      }
      *temp = ((int)MSB<<8) + LSB;
      return ~ack;
}