Interfacing Multiple DS18B20 Temperature Sensors to Arduino:
In this project we will learn about Interfacing Multiple DS18B20 Temperature Sensors to Arduino. Simply we will connect Multiple DS18B20 Temperature Sensors to Arduino and display the temperature values of all the sensors in degree celsius or Fahrenheit. Only one digital pin of Arduino is required to connect several temperature sensor. We can connect maximum of 1024 sensors using I2C Protocol. But here i have shown connecting 3 DS18B20 Temperature Sensors to Arduino.
The DS18B20 temperature sensor is a 1-wire digital temperature sensor. This comes with sealed package lets precisely measure temperatures in wet environments with a simple 1-Wire interface. It communicates on common bus. It means it can connect several devices and read their values using just one digital pin of the Arduino.
DS18B20 Waterproof Digital Temperature Sensor:
This is a pre-wired and waterproofed version of the DS18B20 sensor. Handy for when you need to measure something far away, or in wet conditions. The Sensor can measure the temperature between -55 to 125°C (-67°F to +257°F). The cable is jacketed in PVC.
Because it is digital, there is no any signal degradation even over long distances. These 1-wire digital temperature sensors are fairly precise, i.e ±0.5°C over much of the range. It can give up to 12 bits of precision from the onboard digital-to-analog converter. They work great with any microcontroller using a single digital pin.
The only downside is they use the Dallas 1-Wire protocol, which is somewhat complex and requires a bunch of code to parse out the communication. We toss in a 4.7k resistor, which is required as a pullup from the DATA to the VCC line when using the sensor.
Components Required:
1. Arduino UNO Board
2. Multiple DS18B20 Waterproof Temperature Sensor
3. 16*2 LCD Display
4. 4.7K Resistor
5. Breadboard
6. Connecting Jumper Wires
Circuit Diagram & Connections:
Connect pin 11,12,5,4,3,2 of Arduino to pin 4,6,11,12,13,14 of LCD.
Connect VDD pin of DS18B20 to 5V and GND Pin to Ground. Connect the data pin of all DS18B20 to digital pin 9 of Arduino and also to 4.7K Resistor (Connect other end of 4.7K Resistor to 5V) as shown in the figure below.
Hardware & Design:
By connecting all the sensors to one digital pin of Arduino we have simply designed Digital Thermometer for measuring multiple temperature. So the below picture tells how we have Interfaced Multiple DS18B20 Temperature Sensors to Arduino and how the temperature is being displayed.
Source Code/Program:
For interfacing Multiple DS18B20 Temperature Sensors to Arduino you need two different library
1. Download 1 Wire Library
2. Download Dallas Temperature Library
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#include <LiquidCrystal.h> LiquidCrystal lcd(11, 12, 5, 4, 3, 2); #include <OneWire.h> #include <DallasTemperature.h> #define ONE_WIRE_BUS 9 // Data wire is plugged into port 9 on the Arduino #define precision 12 // OneWire precision Dallas Sensor int sen_number = 0; // Counter of Dallas sensors OneWire oneWire(ONE_WIRE_BUS); DallasTemperature sensors(&oneWire); // Pass our oneWire reference to Dallas Temperature. DeviceAddress T1, T2, T3, T4, T5, T6, T7, T8; // arrays to hold device addresses void setup(void) { lcd.begin(16,2); Serial.begin(9600); //Start serial port Serial.println("Dallas Temperature IC Control Library"); // Start up the library sensors.begin(); // locate devices on the bus Serial.print("Found: "); Serial.print(sensors.getDeviceCount(), DEC); Serial.println(" Devices."); // report parasite power requirements Serial.print("Parasite power is: "); if (sensors.isParasitePowerMode()) Serial.println("ON"); else Serial.println("OFF"); // Search for devices on the bus and assign based on an index. if (!sensors.getAddress(T1, 0)) Serial.println("Not Found Sensor 1"); if (!sensors.getAddress(T2, 1)) Serial.println("Not Found Sensor 2"); if (!sensors.getAddress(T3, 2)) Serial.println("Not Found Sensor 3"); if (!sensors.getAddress(T4, 3)) Serial.println("Not Found Sensor 4"); if (!sensors.getAddress(T5, 4)) Serial.println("Not Found Sensor 5"); if (!sensors.getAddress(T6, 5)) Serial.println("Not Found Sensor 6"); if (!sensors.getAddress(T7, 6)) Serial.println("Not Found Sensor 7"); if (!sensors.getAddress(T8, 7)) Serial.println("Not Found Sensor 8"); // show the addresses we found on the bus for (int k =0; k < sensors.getDeviceCount(); k++) { Serial.print("Sensor "); Serial.print(k+1); Serial.print(" Address: "); if (k == 0) { printAddress(T1); Serial.println(); } else if (k == 1) { printAddress(T2); Serial.println(); } else if (k == 2) { printAddress(T3); Serial.println(); } else if (k == 3) { printAddress(T4); Serial.println(); } else if (k == 4) { printAddress(T5); Serial.println(); } else if (k == 5) { printAddress(T6); Serial.println(); } else if (k == 6) { printAddress(T7); Serial.println(); } else if (k == 7) { printAddress(T8); Serial.println(); } } // set the resolution to 12 bit per device sensors.setResolution(T1, precision); sensors.setResolution(T2, precision); sensors.setResolution(T3, precision); sensors.setResolution(T4, precision); sensors.setResolution(T5, precision); sensors.setResolution(T6, precision); sensors.setResolution(T7, precision); sensors.setResolution(T8, precision); for (int k =0; k < sensors.getDeviceCount(); k++) { Serial.print("Sensor "); Serial.print(k+1); Serial.print(" Resolution: "); if (k == 0) { Serial.print(sensors.getResolution(T1), DEC); Serial.println(); } else if (k == 1) { Serial.print(sensors.getResolution(T2), DEC); Serial.println(); } else if (k == 2) { Serial.print(sensors.getResolution(T3), DEC); Serial.println(); } else if (k == 3) { Serial.print(sensors.getResolution(T4), DEC); Serial.println(); } else if (k == 4) { Serial.print(sensors.getResolution(T5), DEC); Serial.println(); } else if (k == 5) { Serial.print(sensors.getResolution(T6), DEC); Serial.println(); } else if (k == 6) { Serial.print(sensors.getResolution(T7), DEC); Serial.println(); } else if (k == 7) { Serial.print(sensors.getResolution(T8), DEC); Serial.println(); } } } // function to print a device address void printAddress(DeviceAddress deviceAddress) { for (uint8_t i = 0; i < 8; i++) { // zero pad the address if necessary if (deviceAddress[i] < 16) Serial.print("0"); Serial.print(deviceAddress[i], HEX); } } // function to print the temperature for a device void printTemperature(DeviceAddress deviceAddress) { float tempC = sensors.getTempC(deviceAddress); Serial.print("Temp : "); Serial.print(tempC); Serial.print(" Celcius degres "); // Serial.print(" Temp F: "); // Serial.print(DallasTemperature::toFahrenheit(tempC)); } // function to print a device's resolution void printResolution(DeviceAddress deviceAddress) { } void printData(DeviceAddress deviceAddress) { Serial.print("Device Address: "); printAddress(deviceAddress); Serial.print(" "); printTemperature(deviceAddress); Serial.println(); } void loop(void) { // call sensors.requestTemperatures() to issue a global temperature request to all devices on the bus Serial.print("Reading DATA..."); sensors.requestTemperatures(); Serial.println("DONE"); // print the device information for (int k =0; k < sensors.getDeviceCount(); k++) { Serial.print("Sensor "); Serial.print(k+1); Serial.print(" "); if (k == 0) { printData(T1); } else if (k == 1) { printData(T2); } else if (k == 2) { printData(T3); } else if (k == 3) { printData(T4); } else if (k == 4) { printData(T5); } else if (k == 5) { printData(T6); } else if (k == 6) { printData(T7); } else if (k == 7) { printData(T8); } } if (sen_number == sensors.getDeviceCount()) { sen_number = 0; // reset counter // lcd.clear(); // clear screen on LCD } lcd.setCursor(0,0); lcd.print("Sensor Number "); lcd.print(sen_number+1); lcd.setCursor(0,1); lcd.print(" Temp: "); if (sen_number == 0) { lcd.print(sensors.getTempC(T1)); lcd.write((char)223); lcd.print("C "); } else if (sen_number == 1) { lcd.print(sensors.getTempC(T2)); lcd.write((char)223); lcd.print("C "); } else if (sen_number == 2) { lcd.print(sensors.getTempC(T3)); lcd.write((char)223); lcd.print("C "); } else if (sen_number == 3) { lcd.print(sensors.getTempC(T4)); lcd.write((char)223); lcd.print("C "); } else if (sen_number == 4) { lcd.print(sensors.getTempC(T5)); lcd.write((char)223); lcd.print("C "); } else if (sen_number == 5) { lcd.print(sensors.getTempC(T6)); lcd.write((char)223); lcd.print("C "); } else if (sen_number == 6) { lcd.print(sensors.getTempC(T7)); lcd.write((char)223); lcd.print("C "); } else if (sen_number == 7) { lcd.print(sensors.getTempC(T8)); lcd.write((char)223); lcd.print("C "); } Serial.print("Sensor Number="); Serial.println(sen_number); delay(2000); sen_number++ ; } |
Working of Multiple DS18B20 Temperature Sensors with Arduino:
The DS18B20 provides 9 to 12-bit (configurable) temperature readings which indicate the temperature of the device. It communicates over a 1-Wire bus that by definition requires only one data line (and ground) for communication with a central microprocessor. In addition, it can derive power directly from the data line (“parasite power”), eliminating the need for an external power supply.
The core functionality of the DS18B20 is its direct-to-digital temperature sensor. The resolution of the temperature sensor is user-configurable to 9, 10, 11, or 12 bits, corresponding to increments of 0.5°C, 0.25°C, 0.125°C, and 0.0625°C, respectively. The default resolution at power-up is 12-bit.
Each and every DS18B20 has particular device address in HEX format like { 0x28, 0x1D, 0x39, 0x31, 0x2, 0x0, 0x0, 0xF0 }. So the program is designed on the basis of reading temperature from particular device address. So first the Arduino scans the number of sensors. Let us assume 3 sensors are connected here. So it will just displays values of 3 different reading. If more sensors are connected, the reading will switch to multiple values. The value of temperature read by each sensors is displayed after interval of 2 seconds as Sensor Number 1 Temperature, Sensor Number 2 Temperature and upto the value of number of sensor connected.
To learn more about the code you can go through the video below. Or simply read the code as I have commented each and every thing about each line in code.
Video Tutorial & Explanation:
22 Comments
Wonderful project…. I have seen several months ago (don’t remember where..) a similar project but displaying the indoor and few seconds after the outdoor temperatures on a seven segment display since it is designated to be installed in a living room.
Is it possible to modify the current project as described above ?
Check this https://www.how2electronics.com/ds18b20-based-thermometer-using-arduino/
it uses one sensor not two (for indoor/outdoor temperature).
i have made it . it is excellent .
i made it .it is practical and perfect .
I have built this circuit as a test. It works great. The one thing that I cannot figure out is how to make the LCD display Celcius and Fahrenheit at the same time. I was able to figure out the code to display both temps on the serial monitor and My serial monitor shows both temps. I am new to coding and cannot make the code work to show the same information on the LCD. Is there a “quick” explanation of the code to make the LCD Display both temps? Thank You in advance.
Use this formula to convert F to C
C= (F-32)/1.8
Use lcd.print command to display the required temperature. Learn about lcd arduino interfacing code more from google.
If u want to display both temperature at the same time.
I recomend u to use 20×4 LCD.
I have the 20 x 4 display, that is not an issue. I know the math for the conversion. It is the code to make it happen on this particular sketch. This is different code than the other sketches I have done that display both C and F. I will do some more research. Thanks for the reply!
MWL
Hello,
This code works well for 3 sensors when i try to use more than 3 sensors Zero devices is found
This code works for 8 sensors. I have already done the testing
Hi Mostafa. I have same problem. Did you solve this problem?
it works on a arduino uno but for some reason arduino nano not receiving values
hi alex, i’m having a problem .. what if i use dht22 sensor?
DHT22 can be used and interfacing DHT22 with Arduino is more easier.
is it possible to use the program with multiple DHT22?
Can I download the source code somewhere. I can’t seem to copy and paste. Thanks
Hi, I have the display 20×4 but i don´t now how to modify the code to see the 2 sensors. Help me pleaseeeeeeee
Thanks
Hi, I have the display 20×4 but i don´t now how to modify the code to see the 2 sensors. Help me pleaseeeeeeee
Thanks
Hi I need this project with all hardware and with three sensor only difference is each sensor should have a specific name like Hot Water Temperature, Cold Water Temperature, Room Temperature.
Power supply we have is of 12v where we want to place it .
I dont have time to built this so any one who have made this project can contact me at [email protected]
Dear all,
How you fix the initial value in all sensors to measure variation of temperatures?, looks like every ds18b20 has different initial temperatures, are they calibrated wrong or in different regions.
Bonjour, je suis débutant et j’aimerais attribuer un relais à chaque sonde pour déclencher un ventilateur , pouvez vous m’aider svp
merci
Great!!
Can we add RTD/PT100 instead of mentioned Sensor? if yes what all changes in codes to be done.
Thanks.