/*
	main.c
	LM75A數(shù)字溫度計(jì)
*/


#include "Disp.h"
#include "I2C.h"
#include <reg51.h>
#include <string.h>


/*
函數(shù)：Delay()
功能：延時(shí)1ms～65.536s
參數(shù)：
	t>0時(shí)，延時(shí)(t*0.001)s
	t=0時(shí)，延時(shí)65.536s
*/
void Delay(unsigned int t)
{
	do
	{
		TH0 = 0xFC;
		TL0 = 0x66;
		TR0 = 1;
		while ( !TF0 );
		TR0 = 0;
		TF0 = 0;
	} while ( --t != 0 );
}


/*
函數(shù)：SysInit()
功能：系統(tǒng)初始化
*/
void SysInit()
{
	TMOD &= 0xF0;
	TMOD |= 0x01;	//設(shè)置T0為16位定時(shí)器
	DispInit();		//數(shù)碼管掃描顯示初始化
	I2C_Init();		//初始化I2C總線
}


/*
函數(shù)：LM75A_GetTemp
功能：讀出LM75A的溫度值
返回：LM75A溫度寄存器的數(shù)值（乘以0.125可得到攝氏度值）
*/
int LM75A_GetTemp()
{
	unsigned char buf[2];
	int t;
	I2C_Gets(0x90,0x00,2,buf);
	t = buf[0];
	t <<= 8;
	t += buf[1];
	t >>= 5;	//去掉無(wú)關(guān)位
	return t;
}


/*
函數(shù)：ByteToStr()
功能：字節(jié)型變量c轉(zhuǎn)換為十進(jìn)制字符串
*/
void ByteToStr(unsigned char idata *s, unsigned char c)
{
	code unsigned char Tab[] = {100,10};
	unsigned char i;
	unsigned char t;
	for ( i=0; i<2; i++ )
	{
		t = c / Tab[i];
		*s++ = '0' + t;
		c -= t * Tab[i];
	}
	*s++ = '0' + c;
	*s = '\0';
}


/*
函數(shù)：DispTemp()
功能：在數(shù)碼管上顯示出溫度值
參數(shù)：
	t：補(bǔ)碼，除以8以后才是真正溫度值
*/
void DispTemp(int t)
{
	code unsigned char Tab[8][4] =
	{
		"000",
		"125",
		"250",
		"375",
		"500",
		"625",
		"750",
		"875"
	};
	unsigned char buf[4];
	bit s;	//符號(hào)位
	unsigned char i;	//整數(shù)部分
	unsigned char d;	//小數(shù)部分
	unsigned char x;	//臨時(shí)變量
//分離出符號(hào)
	s = 0;
	if ( t < 0 )
	{
		s = 1;
		t = -t;
	}
//分離出整數(shù)和小數(shù)部分
	i = t / 8;
	d = t % 8;
//整數(shù)部分轉(zhuǎn)換成字符串
	ByteToStr(buf,i);
	x = 4 - strlen(buf);
//清除所有顯示
	DispClear();
//顯示符號(hào)
	if ( s ) DispChar(x,'-');
	x++;
//顯示整數(shù)部分
	DispStr(x,buf);
//顯示小數(shù)點(diǎn)
	DispDotOn(4);
//顯示小數(shù)部分
	DispStr(5,Tab[d]);
}


void main()
{
	int t;
	SysInit();
	for (;;)
	{
		t = LM75A_GetTemp();
		DispTemp(t);
		Delay(1000);
	}
}