DS18B20温度传感器 - arduino

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DS18B20测量温度范围是-55℃至125℃，精度为0.5℃。采用单总线进行数据及命令传输，可在同一总线上连接多个DS18B20,并采用地址进行器件选择与数据传输
产品封装
DS18B20产品封装
时序图
DS18B20时序图
典型应用电路

典型电路
寄生供电方式

支持命令集

复位时序

读写时序

arduino 程序

#ifndef DS18B20_h#define DS18B20_h#include <inttypes.h>#if ARDUINO >= 100#include "Arduino.h"       // for delayMicroseconds, digitalPinToBitMask, etc#else#include "WProgram.h"      // for delayMicroseconds#include "pins_arduino.h"  // for digitalPinToBitMask, etc#endif// You can exclude certain features from DS18B20.  In theory, this// might save some space.  In practice, the compiler automatically// removes unused code (technically, the linker, using -fdata-sections// and -ffunction-sections when compiling, and Wl,--gc-sections// when linking), so most of these will not result in any code size// reduction.  Well, unless you try to use the missing features// and redesign your program to not need them!  DS18B20_CRC8_TABLE// is the exception, because it selects a fast but large algorithm// or a small but slow algorithm.// You can exclude CRC checks altogether by defining this to 0#ifndef DS18B20_CRC#define DS18B20_CRC 1#endif// Select the table-lookup method of computing the 8-bit CRC// by setting this to 1.  The lookup table enlarges code size by// about 250 bytes.  It does NOT consume RAM (but did in very// old versions of DS18B20).  If you disable this, a slower// but very compact algorithm is used.#ifndef DS18B20_CRC8_TABLE#define DS18B20_CRC8_TABLE 1#endif#define FALSE 0#define TRUE  1class DS18B20{  private:    uint8_t PIN;    byte bitmask;    // global search state    byte ROM_NO[8];//search到的最新地址暂存    uint8_t LastDiscrepancy;    uint8_t LastDeviceFlag;    byte search_new();    byte senser_number;     void write(uint8_t v);        void write_bytes(const uint8_t *buf, uint16_t count);    // Read a byte.    uint8_t read(void);    void read_bytes(uint8_t *buf, uint16_t count);    // Write a bit. The bus is always left powered at the end, see    // note in write() about that.    void write_bit(uint8_t v);    // Read a bit.    uint8_t read_bit(void);    // Issue a 1-Wire rom select command, you do the reset first.    void select(const uint8_t rom[8]);    // Perform a 1-Wire reset cycle. Returns 1 if a device responds    // with a presence pulse.  Returns 0 if there is no device or the    // bus is shorted or otherwise held low for more than 250uS    uint8_t reset(void);    // Clear the search state so that if will start from the beginning again.    void reset_search();    void search();      public:    void set(byte n);    byte getNumber();    void search_again();//重新搜索          byte senser_addr[8][8];//地址储存，最多8个          DS18B20( uint8_t pin,byte sn);    float get(byte n);    void start(byte n);    void start();    boolean ready();    // Look for the next device. Returns 1 if a new address has been    // returned. A zero might mean that the bus is shorted, there are    // no devices, or you have already retrieved all of them.  It    // might be a good idea to check the CRC to make sure you didn't    // get garbage.  The order is deterministic. You will always get    // the same devices in the same order.#if DS18B20_CRC    // Compute a Dallas Semiconductor 8 bit CRC, these are used in the    // ROM and scratchpad registers.    static uint8_t crc8(const uint8_t *addr, uint8_t len);#endif};#endif

实现文件

/*Base on OneWire v2.2Edit by savage 2014-05-07*/#include "DS18B20.h"DS18B20::DS18B20(uint8_t pin,byte sn){    PIN=pin;    pinMode(pin, OUTPUT);    digitalWrite(PIN,1);    delayMicroseconds(1000);//初始化的时候，先要保证以高电平开始,顺便充电    senser_number=0;    byte li=10;     while(senser_number<sn){//查找传感器，直到数量超过设定值    search_again();     if(!li--)break;//最多10次  }  set(0x3F);//设定为10位模式（默认是12位模式）}void DS18B20::set(byte n){    reset();        write(0xCC);//skip      write(0x4E);//write    write(0);//Th    write(0);//Tl    write(n);//seting 10bit mode B00111111 10位模式}   // Returns 1 if a device asserted a presence pulse, 0 otherwise.//uint8_t DS18B20::reset()    {       uint8_t r;    pinMode(PIN,OUTPUT);// 把总线设置成输出    digitalWrite(PIN,0); // 把总线拉低    delayMicroseconds(480);//拉低电位至少480um，reset      pinMode(PIN,INPUT); // 把总线设置成输入    noInterrupts();     delayMicroseconds(70);          r=!digitalRead(PIN);//传感器回应    interrupts();    delayMicroseconds(410);    return r;}//// Write a bit. Port and bit is used to cut lookup time and provide// more certain timing.//void DS18B20::write_bit(uint8_t v){  pinMode(PIN,OUTPUT);  // 总线设置输出    if (v & 1) {        //写1        noInterrupts();     digitalWrite(PIN,0); // 先把总线拉低        delayMicroseconds(5); // 延迟5us        digitalWrite(PIN,1); // 写入数据        interrupts();        delayMicroseconds(55);    } else {     //写0        noInterrupts();        digitalWrite(PIN,0);        delayMicroseconds(60);          digitalWrite(PIN,1);    interrupts();        delayMicroseconds(5);    }}//// Read a bit. Port and bit is used to cut lookup time and provide// more certain timing.//uint8_t DS18B20::read_bit(){    uint8_t r;      pinMode(PIN,OUTPUT);    noInterrupts();    digitalWrite(PIN,0);//拉低电位1us以上    delayMicroseconds(2);    pinMode(PIN,INPUT);             delayMicroseconds(10);// let pin float, pull up will raise    r = digitalRead(PIN);//必须在15us内采样    interrupts();    delayMicroseconds(50);    return r;}//写void DS18B20::write(uint8_t v) {      noInterrupts();       uint8_t bitMask;    for (bitMask = 0x01; bitMask; bitMask <<= 1) {      DS18B20::write_bit( (bitMask & v)?1:0);    }    interrupts(); }void DS18B20::write_bytes(const uint8_t *buf, uint16_t count) {  for (uint16_t i = 0 ; i < count ; i++)    write(buf[i]);}// Read uint8_t DS18B20::read() {      noInterrupts();       uint8_t bitMask;    uint8_t r = 0;    for (bitMask = 0x01; bitMask; bitMask <<= 1) {      if ( DS18B20::read_bit()) r |= bitMask;    }    interrupts();    return r;}void DS18B20::read_bytes(uint8_t *buf, uint16_t count) {  for (uint16_t i = 0 ; i < count ; i++)    buf[i] = read();}//// Do a ROM select//void DS18B20::select(const uint8_t rom[8]){    uint8_t i;    write(0x55);           // Choose ROM    for (i = 0; i < 8; i++) write(rom[i]);}// 开始温度转换void DS18B20::start(byte n){     reset();   select(senser_addr[n]);   write(0x44);}void DS18B20::start(){     reset();   write(0xCC);//skip   write(0x44);}boolean DS18B20::ready(){      return read()&0x01;}float DS18B20::get(byte n){    if(n>=senser_number)return 210;//超过范围    reset();        select(senser_addr[n]);     write(0xBE); // 写入要求读取温度的命令到DS18B20    byte data[9];    byte i;    for ( i = 0; i < 9; i++) {           // we need 9 bytes    data[i] = read(); // 每次读取1个字节..总共读取9个字节  }  if(crc8(data, 8)!=data[8])return 250;//crc 错误  int raw = (data[1] << 8) | data[0];     return raw*0.0625;        }// You need to use this function to start a search again from the beginning.// You do not need to do it for the first search, though you could.//void DS18B20::reset_search(){  // reset the search state  LastDiscrepancy = 0;  LastDeviceFlag = FALSE;  for(int i = 7; ; i--) {    ROM_NO[i] = 0;    if ( i == 0) break;  }}//// Perform a search. If this function returns a '1' then it has// enumerated the next device and you may retrieve the ROM from the// DS18B20::address variable. If there are no devices, no further// devices, or something horrible happens in the middle of the// enumeration then a 0 is returned.  If a new device is found then// its address is copied to newAddr.  Use DS18B20::reset_search() to// start over.//// --- Replaced by the one from the Dallas Semiconductor web site ---//--------------------------------------------------------------------------// Perform the 1-Wire Search Algorithm on the 1-Wire bus using the existing// search state.// Return TRUE  : device found, ROM number in ROM_NO buffer//        FALSE : device not found, end of search//byte DS18B20::getNumber(){    return senser_number;    }void DS18B20::search_again(){    reset_search();    search();}   void DS18B20::search(){    byte j=0;//最多8个地址    byte i;    senser_number=0;    byte search_err_count=10;//出错后最多重复10次    while(search_new()){                 if(crc8(ROM_NO, 7) != ROM_NO[7]){//CRC验证错误        reset_search();        j=0;        search_err_count--;        if (!search_err_count)break;      }              for(i=0;i<8;i++){                senser_addr[j][i]=ROM_NO[i];            }                   senser_number++;            j++;            if(j ==8)break;             }}byte DS18B20::search_new(){     byte newAddr[8];   uint8_t id_bit_number;   uint8_t last_zero, rom_byte_number, search_result;   uint8_t id_bit, cmp_id_bit;   byte rom_byte_mask, search_direction;   // initialize for search   id_bit_number = 1;   last_zero = 0;   rom_byte_number = 0;   rom_byte_mask = 1;   search_result = 0;   // if the last call was not the last one   if (!LastDeviceFlag)   {      // 1-Wire reset      if (!reset())      {         // reset the search         LastDiscrepancy = 0;         LastDeviceFlag = FALSE;         return FALSE;      }      // issue the search command      write(0xF0);      // loop to do the search      do      {         // read a bit and its complement         id_bit = read_bit();         cmp_id_bit = read_bit();         // check for no devices on 1-wire         //10->all 1; 01->all 0; 00->have 0 and 1;11->no device         if ((id_bit == 1) && (cmp_id_bit == 1))            break;         else         {            // all devices coupled have 0 or 1            if (id_bit != cmp_id_bit)               search_direction = id_bit;  // bit write value for search            else            {               // if this discrepancy if before the Last Discrepancy               // on a previous next then pick the same as last time               if (id_bit_number < LastDiscrepancy)                  search_direction = ((ROM_NO[rom_byte_number] & rom_byte_mask) > 0);               else                  // if equal to last pick 1, if not then pick 0                  search_direction = (id_bit_number == LastDiscrepancy);               // if 0 was picked then record its position in LastZero               if (search_direction == 0)               {                  last_zero = id_bit_number;               }            }            // set or clear the bit in the ROM byte rom_byte_number            // with mask rom_byte_mask            if (search_direction == 1)              ROM_NO[rom_byte_number] |= rom_byte_mask;            else              ROM_NO[rom_byte_number] &= ~rom_byte_mask;            // serial number search direction write bit            write_bit(search_direction);            // increment the byte counter id_bit_number            // and shift the mask rom_byte_mask            id_bit_number++;            rom_byte_mask <<= 1;            // if the mask is 0 then go to new SerialNum byte rom_byte_number and reset mask            //完成一个周期            if (rom_byte_mask == 0)            {                rom_byte_number++;                rom_byte_mask = 1;            }         }      }      while(rom_byte_number < 8);  // loop until through all ROM bytes 0-7      // if the search was successful then      if (!(id_bit_number < 65))      {         // search successful so set LastDiscrepancy,LastDeviceFlag,search_result         LastDiscrepancy = last_zero;         // check for last device         if (LastDiscrepancy == 0)            LastDeviceFlag = TRUE;         search_result = TRUE;      }   }   // if no device found then reset counters so next 'search' will be like a first   if (!search_result || !ROM_NO[0])   {      LastDiscrepancy = 0;      LastDeviceFlag = FALSE;      search_result = FALSE;   }   for (int i = 0; i < 8; i++) newAddr[i] = ROM_NO[i];   return search_result;  }#if DS18B20_CRC// The 1-Wire CRC scheme is described in Maxim Application Note 27:// "Understanding and Using Cyclic Redundancy Checks with Maxim iButton Products"// Compute a Dallas Semiconductor 8 bit CRC directly.// this is much slower, but much smaller, than the lookup table.//uint8_t DS18B20::crc8(const uint8_t *addr, uint8_t len){    uint8_t crc = 0;        while (len--) {        uint8_t inbyte = *addr++;        for (uint8_t i = 8; i; i--) {            uint8_t mix = (crc ^ inbyte) & 0x01;            crc >>= 1;            if (mix) crc ^= 0x8C;            inbyte >>= 1;        }    }    return crc;}#endif

主程序代码

#include "DS18B20.h"DS18B20  ds(9,1);//pin9，连接1个DS18B20void setup() {  SERIAL_BEGIN();  byte i;  byte j;  for (j = 0; j < ds.getNumber(); j++) {    for (i = 0; i < 8; i++) {      PRINT(ds.senser_addr[j][i]);      PRINT(",");    }    PRINT("CRC=");    PRINT(ds.crc8(ds.senser_addr[j], 7) );    PRINT("\n");  }  println(ds.getNumber(),10,serial_puts);}void loop() {   ds.start();//开始测量（所有传感器）  _delay_ms(200);  float a=ds.get(0);  PRINT("temp = ");  if (a>200)    PRINT("CRC error\n");  else  {    PRINT(a);    PRINT("\n");  }}int main(){  setup();  while(1)    loop();}

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