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Arduino with a temperature sensor DS18B20

Arduino in combination with temperature sensor DS18B20

A tutorial is a method of processing a temperature sensor using Arduino.

 

In this example we used the following elements:

 

Connection

At the beginning of the library you want to add to the environment of the Arduino (Sketch -> Include Library -> Add .ZIP Library...). Then connect the contacts of the sensor according to the following table:

 

Pin ArduinoPin Sensor
GNDGND
Pin 10DQ
5 VVdd

 

 

In addition, the sensor requires a 4.7 kω resistor podciągającego between DQ and power 5 Volts - this does not apply to modules that already have this resistor built in.

 

 

 

The scheme of connection of temperature sensor.

 

Service

In order to obtain the temperature from the sensor, we will use the example program DS18x20_Temperature come from the supplied library (File -> Examples -> OneWire -> DS18x20_Temperature).

 

// OneWire DS18S20, DS18B20, DS1822 Temperature Example 
// 
// http://www.pjrc.com/teensy/td_libs_OneWire.html 
// 
// The DallasTemperature library can do all this work for you! 
// http://milesburton.com/Dallas_Temperature_Control_Library 

OneWire ds(10); // on pin 10 (a 4.7 K resistor is necessary) 

void setup(void) { 
 Serial.begin(9600); 
} 

void loop(void) { 
 byte i; 
 byte present = 0; 
 byte type_s; 
 byte data[12]; 
 byte addr[8]; 
 float Celsius, Fahrenheit; 

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

 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 is not valid!"); 
 return; 
 } 
 Serial.println();

// 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; } reset(); select(addr); issues write(0x44, 1); // start conversion, with parasite power on at the end delay(1000); // maybe 750ms is enough, maybe not // we might do a depower() here, but the reset will take care of it. present = reset(); select(addr); issues write(0xBE); // Read Scratchpad Serial.print(" date = "); Serial.print(present, HEX); Serial.print(" "); for ( i = 0; i < 9; i++) { // we need 9 bytes data[i] = 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"); }

 

The results of the program you can see in the following screenshot.

 

 

A screenshot of the serial monitor.