Overview
The DS18B20 1-Wire digital temperature sensor from Maxim IC reports degrees C with 9 to 12-bit precision, -55C to 125C (+/-0.5C). Each sensor has a unique 64-Bit Serial number etched into it - allows for a huge number of sensors to be used on one data bus.
Wiring the DS18B20
![](/download/attachments/327798/image2018-2-8_23-17-46.png?version=1&modificationDate=1518149867000&api=v2)
Normal Power Mode
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Parasitic Power Mode
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Arduino Sample Code
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language | cpp |
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#include <OneWire.h>
#include <DallasTemperature.h>
int#define DS18S20PIN_Pin = 7; //DS18S20 Signal pin on digital 7
//Temperature chip i/oTEMPERATURE 4
OneWire dsoneWire(DS18S20PIN_PinTEMPERATURE); // on digital pin 7
void setup(void) {
Serial.begin(9600); //Start Serial Communication Baud Rate 9600
}
void loop(void) {
float temperature = getTemp();
Serial.println(temperature);
delay(100); //just here to slow down the output so it is easier to read
}
float getTemp(){
//returns the temperature from one DS18S20 in DEG Celsius
byte data[12];
byte addr[8];
if ( !ds.search(addr)) {
//no more sensors on chain, reset search
ds.reset_search();
return -1000;
}
if ( OneWire::crc8( addr, 7) != addr[7]) {
Serial.println("CRC is not valid!");
return -1000;
}
if ( addr[0] != 0x10 && addr[0] != 0x28) {
Serial.print("Device is not recognized");
return -1000;
}
ds.reset();
ds.select(addr);
ds.write(0x44,1); // start conversion, with parasite power on at the end
byte present = ds.reset();
ds.select(addr);
ds.write(0xBE); // Read Scratchpad
for (int i = 0; i < 9; i++) { // we need 9 bytes
data[i] = ds.read();
}
ds.reset_search();
byte MSB = data[1];
byte LSB = data[0];
float tempRead = ((MSB << 8) | LSB); //using two's compliment
float TemperatureSum = tempRead / 16;
return TemperatureSum;
}
DallasTemperature sensors(&oneWire);
float currentTemp = 0;
void setup() {
Serial.begin(115200);
}
void loop() {
sensors.requestTemperatures();
currentTemp = sensors.getTempCByIndex(0);
Serial.print("Temperature: ");
Serial.println(currentTemp);
delay(500);
}
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References