temperature.c

本代码是DS18B20的驱动程序源代码

#include "config.h"
extern void Delay_xus(uint xus);
extern uchar SCRATCHPAD_MAP[8];

//if return value euqal to 0, then get the DS18B20 presence pulse, else erro
uchar DS18B20_Reset(void)
{
	uchar tmp;
	DQ_OUTPUT;
	DQ_L;
	Delay_xus(550);		//the parameter should be more than 480us
	DQ_INPUT;
	Delay_xus(90);		//wait for DS18B20 delay, the delay should be more than 60us, and less than 120us
	if((PINC&(1<<PC0)) == 0x00)
	{
		tmp = 0x00;
	}
	else tmp = 0x01;
	Delay_xus(220);		//wait for present delay, the value will be more than 300us
	return tmp;
}

//extern uchar buf[16];
void Write0Slot(void)
{
	DQ_OUTPUT;
	DQ_L;
	Delay_xus(80);		//the parameter should be more than 60 and less than 120us
	DQ_INPUT;	
	Delay_xus(2);		//2us recovery
}

void Write1Slot(void)
{
	DQ_OUTPUT;
	DQ_L;
	Delay_xus(2);
	DQ_INPUT;
	Delay_xus(80);		//the parameter should be more than 60 and less than 120us
}

uchar ReadSlot(void)
{
	uchar tmp; // read a bit
	DQ_OUTPUT;
	DQ_L;
	Delay_xus(2);
	DQ_INPUT;
	Delay_xus(10);
	if(PINC&(1<<PC0)) tmp = 0x01;
	else tmp = 0x00;
	Delay_xus(80);		//the parameter should be more than 60us and less than 120us
	return tmp;
}

void Transfer_Byte(uchar data)
{	
	uchar i, tmp;
	tmp = data;
	for(i=0; i<8; i++)
	{
	    //if((tmp&0x80) == 0x80)
	    if((tmp&0x01) == 0x01)
	    {
	    	Write1Slot();
	    }
		else
		{
			 Write0Slot();
		}
		//tmp = (tmp<<1);
		tmp = (tmp>>1);
	}
}
	


uchar DS18B20_Initialize(void)
{
	uchar tmp, data, i, j;
	tmp = DS18B20_Reset();
	if(tmp != 0x00) return 1;	//the DS18B20 is absent
	Transfer_Byte(SKIP_ROM);
	Transfer_Byte(WRITE_SCRATCHPAD);
	Transfer_Byte(TH_LIMIT);
	Transfer_Byte(TL_LIMIT);
	Transfer_Byte(Config_REG);
	
	tmp = DS18B20_Reset();
	if(tmp != 0x00) return 1;	//the DS18B20 is absent
	Transfer_Byte(SKIP_ROM);
	Transfer_Byte(READ_SCRATCHPAD);
	for(j=0; j<8; j++)
	{
		data = 0;
		for(i=0; i<8; i++)
		{
			tmp =ReadSlot(); 
			if(tmp == 0x01) data |= 0x80;
			//if(tmp == 0x01) data |= 0x01;
			if(i != 0x07) data = data>>1;
			//if(i != 0x07) data = data<<1;
		}
		SCRATCHPAD_MAP[j] = data;
	}
	
	tmp = DS18B20_Reset();
	if(tmp != 0x00) return 1;	//the DS18B20 is absent
	Transfer_Byte(SKIP_ROM);
	Transfer_Byte(COPY_SCRATCHPAD);
	
	Delay_xus(5000);	//delay 5ms
	Delay_xus(5000);	//delay 5ms
	Delay_xus(5000);	//delay 5ms
	return 0;
}


uint Read_Temperature(void)
{
	uchar tmp, i, j, data;
	uint T_RESULT;
	tmp = DS18B20_Reset();
	if(tmp != 0x00) return 0xffff;	//the DS18B20 is absent
	Transfer_Byte(SKIP_ROM);
	Transfer_Byte(CONVERT_T);
	while(1)		//waiting for the convert complishment
	{
		tmp = ReadSlot();
		if(tmp == 0x01) break;
	}
	
	tmp = DS18B20_Reset();
	if(tmp != 0x00) return 1;	//the DS18B20 is absent
	Transfer_Byte(SKIP_ROM);
	Transfer_Byte(READ_SCRATCHPAD);
	for(j=0; j<8; j++)
	{
		data = 0;
		for(i=0; i<8; i++)
		{
			tmp =ReadSlot(); 
			if(tmp == 0x01) data |= 0x80;
			if(i != 0x07) data = data>>1;
		}
		SCRATCHPAD_MAP[j] = data;
	}
	T_RESULT = SCRATCHPAD_MAP[1];
	T_RESULT = T_RESULT << 8;
	T_RESULT |= SCRATCHPAD_MAP[0];
	return T_RESULT;
}