Wireless Temperature Monitoring System using Arduino, DS18B20, 433 MHz RF, and I2C LCD

This project builds a practical wireless temperature monitoring system using two Arduino UNO boards. One Arduino reads temperature from a DS18B20 sensor and sends it wirelessly through a 433 MHz RF transmitter, while the second Arduino receives the data and shows the live temperature on a 16x2 I2C LCD.

Project overview

The system is divided into two sections:

• Transmitter unit: Arduino UNO + DS18B20 + 433 MHz RF transmitter.
• Receiver unit: Arduino UNO + 433 MHz RF receiver + 16x2 LCD with I2C module.

The DS18B20 sensor works with the OneWire and DallasTemperature libraries in Arduino projects. The 433 MHz RF modules can be used with the VirtualWire library, and the data pin can be connected to an Arduino digital pin. A common 16x2 I2C LCD on Arduino UNO typically uses SDA on A4 and SCL on A5.

Components required

Component	Quantity	Purpose
Arduino UNO	2	One for transmitter, one for receiver
DS18B20 temperature sensor	1	Measures temperature
4.7 kOhm resistor	1	Pull-up resistor for DS18B20 data line
433 MHz RF transmitter module	1	Sends temperature data wirelessly
433 MHz RF receiver module	1	Receives transmitted data
16x2 LCD with I2C backpack	1	Displays received temperature
Breadboard	2	Circuit prototyping
Jumper wires	As needed	Electrical connections
USB cable / 5V supply	2	Power for both Arduinos

Required libraries

Install these libraries from the Arduino IDE Library Manager before uploading the code:

• OneWire
• DallasTemperature for DS18B20 support.
• VirtualWire for 433 MHz RF communication.
• Wire for I2C communication with the LCD.
• LiquidCrystal_I2C for the 16x2 I2C LCD.

Circuit connections

Transmitter wiring

Arduino UNO pin	Connected to	Notes
5V	DS18B20 VCC	Sensor power
GND	DS18B20 GND	Common ground
D2	DS18B20 DATA	OneWire data pin
5V	433 MHz TX VCC	RF transmitter power
GND	433 MHz TX GND	RF transmitter ground
D12	433 MHz TX DATA	RF transmit data pin
D13	Onboard LED	Status blink during transmission

Important: Connect a 4.7 kOhm resistor between DS18B20 DATA and 5V as a pull-up resistor. The DS18B20 requires OneWire communication support and is commonly used this way in Arduino examples.

Receiver wiring

Arduino UNO pin	Connected to	Notes
5V	433 MHz RX VCC	RF receiver power
GND	433 MHz RX GND	RF receiver ground
D11	433 MHz RX DATA	RF receive data pin
5V	LCD VCC	LCD power
GND	LCD GND	LCD ground
A4	LCD SDA	I2C data line on UNO.
A5	LCD SCL	I2C clock line on UNO.
D13	Onboard LED	Status blink on packet receive

How the system works

1. The DS18B20 sensor measures temperature and sends the reading to the transmitter Arduino using the OneWire protocol.
2. The transmitter Arduino converts the temperature value into text format and sends it through the 433 MHz RF transmitter using VirtualWire.
3. The RF receiver module captures the wireless data and passes it to the receiver Arduino through a digital input pin.
4. The receiver Arduino decodes the received text and displays it on the 16x2 I2C LCD.
5. The loop repeats continuously, so the displayed temperature keeps updating in real time.

Arduino code structure

Transmitter code features

• Reads temperature from DS18B20 every 1 second.
• Detects sensor disconnection and sends ERR if the sensor fails.
• Sends temperature as ASCII text over 433 MHz RF.
• Toggles the onboard LED on every successful transmission.

Receiver code features

• Listens continuously for incoming RF packets.
• Shows Waiting... during startup.
• Displays temperature in Celsius on the LCD when data arrives.
• Shows Sensor Error if transmitter reports a fault.
• Shows No Signal if no packet is received for 3 seconds.

File list

• transmitter.ino — code for the temperature sensing and RF transmission unit.
• receiver.ino — code for the RF receiving and LCD display unit.

Upload steps

1. Open transmitter.ino in Arduino IDE and select Arduino UNO board.
2. Install all required libraries.
3. Upload transmitter code to the first Arduino UNO.
4. Open receiver.ino and upload it to the second Arduino UNO.
5. Power both boards.
6. Adjust the LCD I2C address if your display does not use 0x27; many modules use 0x27 or 0x3F.

Troubleshooting

1. LCD shows nothing

• Check LCD power and GND.
• Verify SDA is connected to A4 and SCL to A5 on Arduino UNO.
• Confirm the I2C address; scan for 0x27 or 0x3F if needed.
• Make sure the contrast potentiometer on the LCD backpack is adjusted correctly.

2. Receiver shows No Signal

• Check RF module wiring carefully.
• Confirm transmitter DATA pin matches vw_set_tx_pin() and receiver DATA pin matches vw_set_rx_pin().
• Verify both sketches use the same VirtualWire bit rate, here 2000 bps.
• Keep both modules powered properly; some hobby examples note shared ground and stable supply are important for reliable operation.

3. Temperature shows Sensor Error

• Check the DS18B20 pin order.

• Verify the 4.7 kOhm pull-up resistor between DATA and 5V.

• Make sure the sensor data wire is connected to pin D2 in the sketch.

• Recheck OneWire and DallasTemperature library installation.### 4. Code compilation errors

• Install missing libraries from Sketch > Include Library > Manage Libraries.

• Make sure the included library names match the code exactly.

• If LiquidCrystal_I2C.h is missing, install a compatible LiquidCrystal_I2C library.

Practical notes

• These simple 433 MHz RF modules are low-cost and easy to use, but they are not highly robust in noisy environments.
• Keep antenna wires attached for better range.
• Avoid placing the RF modules too close to switching power supplies.
• Start by testing the DS18B20 and LCD separately before combining the full system.

Wokwi Simulation

This project was partially simulated using Wokwi.

Components Simulated

• Arduino UNO
• DS18B20 Temperature Sensor
• 16x2 I2C LCD Display

Limitation

Wokwi currently does not support 433 MHz RF transmitter and receiver modules directly, so only the sensor and LCD section were simulated.

Simulation Preview

Future improvements

• Add checksum or packet framing for stronger communication reliability.
• Send both Celsius and Fahrenheit values.
• Add min/max temperature logging.
• Use an ESP32 receiver and upload readings to Wi-Fi or cloud dashboards.
• Replace 433 MHz ASK modules with LoRa for longer range and better reliability.
• Add buzzer or relay output for over-temperature alarm.
• Add battery supply and low-power mode for remote sensing nodes.

Resume description

Wireless Temperature Monitoring System using Arduino and RF Communication
Designed and developed a wireless temperature monitoring system using two Arduino UNO boards, a DS18B20 digital temperature sensor, 433 MHz RF transmitter/receiver modules, and a 16x2 I2C LCD. Implemented real-time wireless data transmission, live temperature display, sensor fault handling, and signal-loss indication using Embedded C / Arduino programming.

One line project summary

Built a real-time wireless temperature monitoring system using Arduino UNO, DS18B20 sensor, RF modules, and I2C LCD for wireless data transmission and live temperature display.