ESP8266 - Температурный датчик DS18B20

abdurino

New member
Считывание температуры с DS18B20,
первое значение почему-то 85, остальные норм.

Подключение
черный - GND
красный - 3V
желтый - pin 14
дополнительно между красным и желтым ставим резистор 4.7К

код заработал с ардуино без изменений.
при компиляции ругается, мол работа OneWire на ESP не гарантирована. Но всё ОК.
Код:
// -- temperature
#include <OneWire.h>
#define TempPin 14
OneWire  ds(TempPin);

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:

  String str;

  if (Serial.available() > 0) {
    str = Serial.readStringUntil('\n');
    if (str == "temp") {
      float temp = 0;
      bool is_get_tmp = get_temp(&temp);
      if (is_get_tmp) {
        //Serial.print(getTimeStr());
        Serial.print("Temperature:");
        Serial.print(" ");
        Serial.println(float_to_string(temp));
      }
    }
  }

}


String float_to_string(float f) {
  char charVal[10];
  dtostrf(f, 4, 1, charVal);
  String temp_str = String(charVal);
  return temp_str;
}


bool get_temp(float *temp) {
  byte i;
  byte present = 0;
  byte type_s;
  byte data[12];
  byte addr[8];
  float celsius, fahrenheit;

  if ( !ds.search(addr)) {
    Serial.println("No more addresses.");
    ds.reset_search();
    delay(250);
    return false;
  }

  /*Serial.print("ROM =");
  for( i = 0; i < 8; i++) {
    Serial.write(' ');
    Serial.print(addr[i], HEX);
  }*/

  if (OneWire::crc8(addr, 7) != addr[7]) {
    Serial.println("CRC error");
    return false;
  }

  // the first ROM byte indicates which chip
  switch (addr[0]) {
    case 0x10:
      //Serial.println("  Chip = DS18S20");  // or old DS1820
      type_s = 1;
      break;
    case 0x28:
      //Serial.println("  Chip = DS18B20");
      type_s = 0;
      break;
    case 0x22:
      //Serial.println("  Chip = DS1822");
      type_s = 0;
      break;
    default:
      //Serial.println("Device is not a DS18x20 family device.");
      return false;
  }

  ds.reset();
  ds.select(addr);
  ds.write(0x44, 1);        // start conversion, with parasite power on at the end

  //delay(1000);     // maybe 750ms is enough, maybe not
  // we might do a ds.depower() here, but the reset will take care of it.


  present = ds.reset();
  ds.select(addr);
  ds.write(0xBE);         // Read Scratchpad

  /*Serial.print("  Data = ");
  Serial.print(present, HEX);
  Serial.print(" ");*/
  for ( i = 0; i < 9; i++) {           // we need 9 bytes
    data[i] = ds.read();
    //Serial.print(data[i], HEX);
    //Serial.print(" ");
  }
  /*Serial.print(" CRC=");
  Serial.print(OneWire::crc8(data, 8), HEX);
  Serial.println();*/

  // Convert the data to actual temperature
  // because the result is a 16 bit signed integer, it should
  // be stored to an "int16_t" type, which is always 16 bits
  // even when compiled on a 32 bit processor.
  int16_t raw = (data[1] << 8) | data[0];
  if (type_s) {
    raw = raw << 3; // 9 bit resolution default
    if (data[7] == 0x10) {
      // "count remain" gives full 12 bit resolution
      raw = (raw & 0xFFF0) + 12 - data[6];
    }
  } else {
    byte cfg = (data[4] & 0x60);
    // at lower res, the low bits are undefined, so let's zero them
    if (cfg == 0x00) raw = raw & ~7;  // 9 bit resolution, 93.75 ms
    else if (cfg == 0x20) raw = raw & ~3; // 10 bit res, 187.5 ms
    else if (cfg == 0x40) raw = raw & ~1; // 11 bit res, 375 ms
    //// default is 12 bit resolution, 750 ms conversion time
  }
  celsius = (float)raw / 16.0;
  /*fahrenheit = celsius * 1.8 + 32.0;
  Serial.print("  Temperature = ");
  Serial.print(celsius);
  Serial.print(" Celsius, ");
  Serial.print(fahrenheit);
  Serial.println(" Fahrenheit");*/

  ds.reset_search();

  *temp = celsius;
  return true;
}
 
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