An ARM7-based embedded system built with the LPC2148 to automate examination timing, monitor room temperature, provide visual status indication, and handle examination interruptions.
The Smart Exam Hall Monitoring and Management System integrates several LPC2148 peripherals into one embedded application. It provides real-time examination timing, temperature monitoring, a countdown display, pause/resume control, and an examination-completion indication.
This project was developed as a practical application for understanding and implementing LPC2148 peripherals.
The diagram below shows the keypad, switches, and LM35 sensor connected to the LPC2148, along with the display, LEDs, and buzzer driven by the controller.
- Real-time date and time display using the RTC
- Examination-duration configuration using a 4×4 matrix keypad
- Examination countdown timer
- Remaining examination time on two multiplexed 7-segment displays
- Room-temperature monitoring using the LM35 and ADC
- Temperature display on the 16×2 LCD
- Three-level examination-status indication:
- Green LED — more than 70% of examination time remaining
- Yellow LED — between 30% and 70% remaining
- Red LED — 30% or less remaining
- Pause/Resume functionality using an external interrupt
- Automatic recording of examination start and end times
- Buzzer indication when the examination reaches zero
- LCD-based status and configuration interface
- LPC2148 ARM7TDMI microcontroller
- 16×2 LCD
- 4×4 matrix keypad
- LM35 temperature sensor
- 10-bit ADC
- RTC
- Two 7-segment displays
- Green, yellow, and red LEDs
- Buzzer
- Push switches
- USB-UART / DB-9 interface
- GPIO
- RTC
- ADC
- External Interrupts (EINT0/EINT1)
- VIC (Vectored Interrupt Controller)
- LCD interfacing
- Keypad interfacing
- Timer/delay functions
- 7-segment multiplexing
After power-up, the LCD displays the current RTC time and room temperature.
Time: 12:30:45
Temp: 28°C
The LM35 produces an analog voltage proportional to temperature. The LPC2148 ADC converts this voltage into a digital value, which is then converted into a temperature reading.
The administrator enters configuration mode using the keypad and can configure the following:
- RTC date and time
- Examination start time
- Examination duration
When the configured examination time is reached, the system:
- Records the examination start time using the RTC.
- Starts the examination countdown.
- Displays the remaining time on the multiplexed 7-segment displays.
- Updates the LED status according to the remaining time.
The two 7-segment displays show the remaining examination time in minutes:
30 → 29 → 28 → ... → 02 → 01 → 00
The displays are multiplexed using shared segment lines.
The LEDs provide a quick visual indication of the remaining examination time.
| Remaining time | Indication |
|---|---|
| More than 70% of examination duration | Green LED |
| More than 30% and up to 70% | Yellow LED |
| 30% or less | Red LED |
| 00 minutes | Buzzer |
An external interrupt provides pause/resume functionality:
Running → Paused → Running
The countdown resumes from the remaining time.
When the countdown reaches 00, the system activates the buzzer, marks the examination as complete, records the end time using the RTC, and displays the relevant information on the LCD.
This project demonstrates how multiple microcontroller peripherals can be integrated into an examination-management application for automated timing, environmental monitoring, status indication, and interruption handling.
Note: This project was developed as a practical LPC2148 peripheral-integration exercise, with the objective of understanding and implementing the individual hardware peripherals through a single application.
Pravin Patil
Embedded Systems / ARM7 Project