单总线控制DS18B20温度传感器

单总线控制DS18B20温度传感器一DS18B20通过单总线初始化时序如下:由上图可见,当主机要操作DS18B20时,需要把总线打底,并持续480us以960us 然后释放总线(即拉高),当时间流逝15-60us的时候,DS18B20若存在且没有坏的话,它会把总线拉低,并持续60-240us .在这段时间主机可以查看总线状态,来确定初始化完成 .二DS18B20通过单总线读写时序如下:由上图可以看出,主机要读或写DS18B20时,需要要将总线接低并持续15us,上面的两个时序是写的时序,主机在接低总线的15us后继续拉低总线,持续15-30us. 在这个时间内DS18B20采样0,完成0的写入.主机拉低总线15us后拉高总线然后持续15-30us等待DS18B20采样完成 1的写入.下面的两个图是读的时序图.主机拉低总线并持续15us后,释放总线.如果DS18B20要输出0就继续拉低总线,若要输出1 就拉高总线,并持续15-30us,等待主机查询总线状态完成 0或者1的读写.三DS18B20的ROM操作命令如下:四DS18B20的存储器操作命令如下:五DS18B20内部9个字节存储器以及E2RAM:六DS18B20内部存储温度字节格式:七DS18B20操作的C语言程序:/*************************此部分为18B20的驱动程序*************************************/#include <reg52.H>#include <intrins.h>sbit D18B20=P3^7;#define NOP() _nop_() /* 定义空指令 */#define _Nop() _nop_() /*定义空指令*/void TempDelay (unsigned char idata us);void Init18b20 (void);void WriteByte (unsigned char idata wr); //单字节写入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,D[10];unsigned char idata temp_buff[9]; //存储读取的字节，read scratchpad为9字节，read rom ID为8字节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, 1 96, 154,217, 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, 2 31, 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, 2 13, 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:延时处理*parameter:*Return:*Modify:*************************************************************/void TempDelay (unsigned char idata us){while(us--);}/*************************************************************Function:18B20初始化*parameter:*Return:*Modify:*************************************************************/void Init18b20 (void){_nop_();D18B20=0;TempDelay(50); //delay 530 uS//80_nop_();D18B20=1;TempDelay(10); //delay 100 uS//14_nop_();_nop_();_nop_();if(D18B20==0)flag = 1; //detect 1820 success!elseflag = 0; //detect 1820 fail!TempDelay(15); //20_nop_();_nop_();D18B20 = 1;}/************************************************************ *Function:向18B20写入一个字节*parameter:*Return:*Modify:*************************************************************/ void WriteByte (unsigned char idata wr) //单字节写入{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:读18B20的一个字节*parameter:*Return:*Modify:*************************************************************/ unsigned char ReadByte (void) //读取单字节{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:读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校验*parameter:*Return:*Modify:*************************************************************/ unsigned char CRC (unsigned char j){unsigned char idata i,crc_data=0;for(i=0;i<j;i++) //查表校验crc_data = CrcTable[crc_data^temp_buff[i]];return (crc_data);}/************************************************************ *Function:读取温度*parameter:*Return:*Modify:*************************************************************/ void GemTemp (void){read_bytes (9);if (CRC(9)==0) //校验正确{Temperature = temp_buff[1]*0x100 + temp_buff[0];// Temperature *= 0.625;Temperature /= 16;TempDelay(1);}}/************************************************************ *Function:内部配置*parameter:*Return:*Modify:*************************************************************/ void Config18b20 (void) //重新配置报警限定值和分辨率{Init18b20();WriteByte(0xcc); //skip romWriteByte(0x4e); //write scratchpadWriteByte(0x19); //上限WriteByte(0x1a); //下限WriteByte(0x7f); //set 11 bit (0.125)Init18b20();WriteByte(0xcc); //skip romWriteByte(0x48); //保存设定值Init18b20();WriteByte(0xcc); //skip romWriteByte(0xb8); //回调设定值}/************************************************************ *Function:读18B20ID*parameter:*Return:*Modify:*************************************************************/ void ReadID (void)//读取器件 id{Init18b20();WriteByte(0x33); //read romread_bytes(8);}/************************************************************ *Function:18B20ID全处理*parameter:*Return:*Modify:*************************************************************/ void TemperatuerResult(void){p = id_buff;ReadID();Config18b20();Init18b20 ();WriteByte(0xcc); //skip romWriteByte(0x44); //Temperature convertInit18b20 ();WriteByte(0xcc); //skip romWriteByte(0xbe); //read Temperaturep = temp_buff;GemTemp();}unsigned int TempTick=0;void GetTemp(){if(TIM==1){ TIM=0;TemperatuerResult();D[5]=Temperature;}}/*************************************[ t1 (0.5ms)中断] 中断中做 PWM 输出------------1000/(0.02ms*250)=200Hz*************************************/void T1zd(void) interrupt 3{TH1 = 0xfe; //11.0592TL1 = 0x33;TIM++;}。