/*************************此部分為18B20的驅動程序*************************************/

#include <reg52.H>
#include <intrins.h>

sbit    D18B20=P3^7;
#define  NOP()   _nop_()   /* 定義空指令 */
#define  _Nop()  _nop_()   /*定義空指令*/

void TempDelay (unsigned char idata us);
void Init18b20 (void);
void WriteByte (unsigned char idata wr);  //單字節寫入
void read_bytes (unsigned char idata j);
unsigned char CRC (unsigned char j);
void GemTemp (void);
void Config18b20 (void);
void ReadID (void);
void TemperatuerResult(void);


bit  flag;
unsigned int  idata Temperature;
unsigned char idata temp_buff[9]; //存儲讀取的字節，read scratchpad為9字節，read rom ID為8字節
unsigned char idata id_buff[8];
unsigned char idata *p,TIM;
unsigned char idata crc_data;


unsigned char code CrcTable [256]={
0,  94, 188,  226,  97,  63,  221,  131,  194,  156,  126,  32,  163,  253,  31,  65,
157,  195,  33,  127,  252,  162,  64,  30,  95,  1,  227,  189,  62,  96,  130,  220,
35,  125,  159,  193,  66,  28,  254,  160,  225,  191,  93,  3,  128,  222,  60,  98,
190,  224,  2,  92,  223,  129,  99,  61,  124,  34,  192,  158,  29,  67,  161,  255,
70,  24,  250,  164,  39,  121,  155,  197,  132,  218,  56,  102,  229,  187,  89,  7,
219,  133, 103,  57,  186,  228,  6,  88,  25,  71,  165,  251,  120,  38,  196,  154,
101,  59, 217,  135,  4,  90,  184,  230,  167,  249,  27,  69,  198,  152,  122,  36,
248,  166, 68,  26,  153,  199,  37,  123,  58,  100,  134,  216,  91,  5,  231,  185,
140,  210, 48,  110,  237,  179,  81,  15,  78,  16,  242,  172,  47,  113,  147,  205,
17,  79,  173,  243,  112,  46,  204,  146,  211,  141,  111,  49,  178,  236,  14,  80,
175,  241, 19,  77,  206,  144,  114,  44,  109,  51,  209,  143,  12,  82,  176,  238,
50,  108,  142,  208,  83,  13,  239,  177,  240,  174,  76,  18,  145,  207,  45,  115,
202,  148, 118,  40,  171,  245,  23,  73,  8,  86,  180,  234,  105,  55,  213, 139,
87,  9,  235,  181,  54,  104,  138,  212,  149,  203,  41,  119,  244,  170,  72,  22,
233,  183,  85,  11,  136,  214,  52,  106,  43,  117,  151,  201,  74,  20,  246,  168,
116,  42,  200,  150,  21,  75,  169,  247,  182,  232,  10,  84,  215,  137,  107,  53}; 
//
/************************************************************
*Function:延時處理
*parameter:
*Return:
*Modify:
*************************************************************/
void TempDelay (unsigned char idata us)
{
	while(us--);
}

/************************************************************
*Function:18B20初始化
*parameter:
*Return:
*Modify:
*************************************************************/
void Init18b20 (void)
{
	D18B20=1;
	_nop_();
	D18B20=0;
	TempDelay(80);   //delay 530 uS//80
	_nop_();
	D18B20=1;
	TempDelay(14);   //delay 100 uS//14
	_nop_();
	_nop_();
	_nop_();
	
	if(D18B20==0)
		flag = 1;   //detect 1820 success!
	else
		flag = 0;    //detect 1820 fail!
	TempDelay(20);       //20
	_nop_();
	_nop_();
	D18B20 = 1;
}

/************************************************************
*Function:向18B20寫入一個字節
*parameter:
*Return:
*Modify:
*************************************************************/
void WriteByte (unsigned char idata wr)  //單字節寫入
{
	unsigned char idata i;
	for (i=0;i<8;i++)
	{
		D18B20 = 0;
		_nop_();
		D18B20=wr&0x01;
		TempDelay(3);   //delay 45 uS //5
		_nop_();
		_nop_();
		D18B20=1;
		wr >>= 1;
	}
}

/************************************************************
*Function:讀18B20的一個字節
*parameter:
*Return:
*Modify:
*************************************************************/
unsigned char ReadByte (void)     //讀取單字節
{
	unsigned char idata i,u=0;
	for(i=0;i<8;i++)
	{
		D18B20 = 0;
		u >>= 1;
		D18B20 = 1;
		if(D18B20==1)
		u |= 0x80;
		TempDelay (2);
		_nop_();
	}
	return(u);
}

/************************************************************
*Function:讀18B20
*parameter:
*Return:
*Modify:
*************************************************************/
void read_bytes (unsigned char idata j)
{
	 unsigned char idata i;
	 for(i=0;i<j;i++)
	 {
		  *p = ReadByte();
		  p++;
	 }
}

/************************************************************
*Function:CRC校驗
*parameter:
*Return:
*Modify:
*************************************************************/
unsigned char CRC (unsigned char j)
{
   	unsigned char idata i,crc_data=0;
  	for(i=0;i<j;i++)  //查表校驗
    	crc_data = CrcTable[crc_data^temp_buff[i]];
    return (crc_data);
}

/************************************************************
*Function:讀取溫度
*parameter:
*Return:
*Modify:
*************************************************************/
void GemTemp (void)
{
   read_bytes (9);
   if (CRC(9)==0) //校驗正確
   {
	    Temperature = temp_buff[1]*0x100 + temp_buff[0];
//	    Temperature *= 0.625;
		Temperature /= 16;
		TempDelay(1);
    }
}

/************************************************************
*Function:內部配置
*parameter:
*Return:
*Modify:
*************************************************************/
void Config18b20 (void)  //重新配置報警限定值和分辨率
{
     Init18b20();
     WriteByte(0xcc);  //skip rom
     WriteByte(0x4e);  //write scratchpad
     WriteByte(0x19);  //上限
     WriteByte(0x1a);  //下限
     WriteByte(0x7f);     //set 11 bit (0.125)
     Init18b20();
     WriteByte(0xcc);  //skip rom
     WriteByte(0x48);  //保存設定值
     Init18b20();
     WriteByte(0xcc);  //skip rom
     WriteByte(0xb8);  //回調設定值
}

/************************************************************
*Function:讀18B20ID
*parameter:
*Return:
*Modify:
*************************************************************/
void ReadID (void)//讀取器件 id
{
	Init18b20();
	WriteByte(0x33);  //read rom
	read_bytes(8);
}

/************************************************************
*Function:18B20ID全處理
*parameter:
*Return:
*Modify:
*************************************************************/
void TemperatuerResult(void)
{
  	p = id_buff;
  	ReadID();
  	Config18b20();
	Init18b20 ();
	WriteByte(0xcc);   //skip rom
	WriteByte(0x44);   //Temperature convert

	Init18b20 ();
	WriteByte(0xcc);   //skip rom
	WriteByte(0xbe);   //read Temperature
	p = temp_buff;
	GemTemp();
}


void GetTemp()
{       
     if(TIM==1)
	{  TIM=0;
	   TemperatuerResult();
	}

}

/*************************************
 [ t1 (0.5ms)中斷] 中斷中做 PWM 輸出
  ------------1000/(0.02ms*250)=200Hz
*************************************/
void T1zd(void) interrupt 3 
{
   TH1 = 0xfe;    //11.0592
   TL1 = 0x33;
   TIM++;

}