Description
This module measures the temperature and reports it through the 1-wire bus to the Arduino. It uses the extremely popular DS18b20 digital thermometer.
Specs
The DS18B20 digital thermometer provides 9-bit to 12-bit Celsius temperature measurements and has an alarm function with nonvolatile user-programmable upper and lower trigger points. The DS18B20 communicates over a 1-Wire® bus that by definition requires only one data line (and ground) for communication with a central microprocessor. It has an operating temperature range of -55°C to +125°C and is accurate to ±0.5°C over the range of -10°C to +85°C. In addition, the DS18B20 can derive power directly from the data line (“parasite power”), eliminating the need for an external power supply.
Each DS18B20 has a unique 64-bit serial code, which allows multiple DS18B20s to function on the same 1-Wire bus.
Parts Required
You will require the following
Arduino UNO (or equivalent)
KY-001 Temperature sensor module
USB cable
Connections
Pin – = connect to GND
Pin (middle) = connect to +5V
Pin S = Signal, connect to Arduino Digital port 10
Code
Arduino Example
[codesyntax lang=”cpp”]
#include <OneWire.h> // DS18S20 Temperature chip i/o OneWire ds(10); // on pin 10 void setup(void) { // initialize inputs/outputs // start serial port Serial.begin(9600); } void loop(void) { //For conversion of raw data to C int HighByte, LowByte, TReading, SignBit, Tc_100, Whole, Fract; byte i; byte present = 0; byte data[12]; byte addr[8]; if ( !ds.search(addr)) { Serial.print("No more addresses.\n"); ds.reset_search(); return; } Serial.print("R="); for( i = 0; i < 8; i++) { Serial.print(addr[i], HEX); Serial.print(" "); } if ( OneWire::crc8( addr, 7) != addr[7]) { Serial.print("CRC is not valid!\n"); return; } if ( addr[0] == 0x10) { Serial.print("Device is a DS18S20 family device.\n"); } else if ( addr[0] == 0x28) { Serial.print("Device is a DS18B20 family device.\n"); } else { Serial.print("Device family is not recognized: 0x"); Serial.println(addr[0],HEX); return; } 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("P="); 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(); //Conversion of raw data to C LowByte = data[0]; HighByte = data[1]; TReading = (HighByte << 8) + LowByte; SignBit = TReading & 0x8000; // test most sig bit if (SignBit) // negative { TReading = (TReading ^ 0xffff) + 1; // 2's comp } Tc_100 = (6 * TReading) + TReading / 4; // multiply by (100 * 0.0625) or 6.25 Whole = Tc_100 / 100; // separate off the whole and fractional portions Fract = Tc_100 % 100; if (SignBit) // If its negative { Serial.print("-"); } Serial.print(Whole); Serial.print("."); if (Fract < 10) { Serial.print("0"); } Serial.print(Fract); Serial.print("\n"); //End conversion to C }
[/codesyntax]