A microcontroller-based temperature monitoring system designed to measure temperature continuously and activate visual and audible warnings when a defined thermal limit is exceeded.
The system uses an NTC thermistor as the temperature sensor and an Arduino Uno to process the analog sensor signal.
The calculated temperature is displayed on a 16×2 LCD while an LED and buzzer provide automatic warning outputs when the measured temperature exceeds the programmed threshold.
Circuit Integration, Embedded Logic, Sensor Setup & System Testing
Within the team project, my work focused on integrating the sensing hardware with the Arduino control system and helping validate the operation of the completed device.
- Supported circuit integration between the thermistor, Arduino, LCD, LED, buzzer, and user input.
- Worked with the thermistor sensing circuit used to convert temperature changes into an Arduino analog input.
- Contributed to embedded control logic for temperature monitoring and alarm activation.
- Supported implementation of the temperature threshold used to activate the warning outputs.
- Tested system behavior across changing temperature conditions.
- Verified LCD temperature output and LED/buzzer alarm behavior.
- Supported debugging and validation of the integrated hardware and software system.
- Contributed to technical documentation of the final system.
The complete temperature alarm system was developed collaboratively by the project team. This section highlights my individual work in circuit integration, control logic, testing, and documentation.
The system follows a simple sense-process-display-alert architecture centered around the Arduino Uno.
The NTC thermistor changes resistance as temperature changes.
Arduino converts the analog reading into resistance and temperature.
The calculated temperature appears on the LCD in Celsius or Fahrenheit.
LED and buzzer activate when temperature exceeds the programmed threshold.
Electronic components combine sensing, processing, user feedback, and alarm functionality.
Processes the thermistor signal and executes the temperature monitoring program.
Provides a resistance that varies with temperature.
Displays the calculated temperature to the user.
Provides a visible indication when the temperature limit is exceeded.
Generates an audible warning during an over-temperature condition.
Toggles the displayed temperature between Celsius and Fahrenheit.
The Arduino reads the thermistor through analog input A0 and converts the measured voltage into thermistor resistance.
The program then applies the Steinhart-Hart relationship to calculate temperature in degrees Celsius.
Analog input measures the thermistor circuit voltage.
ADC output is converted into a corresponding voltage.
Voltage-divider behavior is used to determine thermistor resistance.
Steinhart-Hart coefficients convert resistance into temperature.
The Arduino continuously executes a closed monitoring loop approximately every 500 milliseconds.
Acquire the current thermistor analog signal.
Convert the sensor measurement to a temperature value.
Display temperature using the selected temperature unit.
Compare measured temperature against the programmed limit.
Activate the LED and buzzer when the limit is exceeded.
The alarm threshold was programmed at 31°C.
LED + buzzer activate when the measured temperature exceeds this limit.
LED off
Buzzer off
Temperature displayed
LED on
Buzzer on
Temperature displayed
The system provides both continuous information and immediate warning feedback to the user.
Displays the current calculated temperature to two decimal places.
Changes the display mode between Celsius and Fahrenheit.
Indicates an over-temperature condition.
Immediately alerts the user when the threshold is exceeded.
Testing focused on verifying that sensor readings, display behavior, user input, and alarm outputs operated together as one integrated system.
- Verified temperature readings changed in response to thermistor conditions.
- Checked LCD updates during continuous sensor monitoring.
- Tested Celsius and Fahrenheit display switching.
- Confirmed the LED and buzzer responded to the programmed temperature threshold.
- Debugged hardware and program behavior during system integration.
This project demonstrated how a physical sensor measurement can be converted into meaningful digital information and used to trigger automated system behavior.
Integrating the thermistor, Arduino, LCD, button, LED, and buzzer required both hardware and software components to operate together reliably.
The project strengthened my experience with sensor interfacing, embedded programming, circuit integration, threshold-based control logic, and mechatronic system testing.
Arduino Temperature Alarm Project
The project documentation contains the circuit schematic, physical prototype, system flowchart, Arduino program, and video demonstration references.