Arduino Data Logger Shield & Sensor Test using ATmega328P with Proteus Simulation

Introduction

This microcontroller project demonstrates a simple yet practical Arduino data logger shield sensor test using an ATmega328P in Proteus simulation.
The system reads light intensity from an LDR and temperature from a TMP36 sensor, then sends real-time data to a serial terminal.
It’s a beginner-friendly embedded systems project that explains analog sensing, external voltage reference usage, and serial monitoring.
Designed for DIY electronics learners, this project shows how sensors behave before moving to real hardware.
Proteus makes it easy to test, debug, and understand the working principle without physical components.

How the Project Works (Overview)

The ATmega328P continuously samples two analog sensors:

• An LDR for light intensity

• A TMP36 for temperature measurement

Using a 3.3V external analog reference (AREF), the microcontroller converts sensor voltages into digital values via its internal ADC.
The processed data is categorized (light levels) and converted into Celsius and Fahrenheit for temperature, then transmitted over UART to a serial terminal.

Block Diagram / Workflow Explanation

1. LDR + Resistor Divider produces a voltage proportional to light intensity

2. TMP36 Sensor outputs an analog voltage based on temperature

3. ATmega328P ADC reads both sensor voltages using external AREF

4. Firmware Logic converts raw ADC values into readable units

5. UART (Serial Monitor) displays live sensor data every second

Key Features

• Uses external analog reference for accurate sensor readings

• Simultaneous monitoring of temperature and light

• Real-time serial output for debugging and logging

• Threshold-based light intensity classification

• Fully testable in Proteus VSM simulation

• Minimal hardware with clean firmware logic

Components Used

• ATmega328P microcontroller

• TMP36 analog temperature sensor

• LDR (Light Dependent Resistor)

• 10kΩ resistor (voltage divider)

• 3.3V reference source

• Crystal oscillator (32.768 kHz for RTC shield context)

• Serial terminal (UART)

Applications

• Environmental monitoring systems

• Temperature and light data logging

• Smart room or greenhouse monitoring

• Embedded systems learning labs

• Sensor calibration testing

• Arduino-based IoT prototypes

Explanation of the Code (High-Level)

The firmware initializes serial communication for data output and configures the ADC to use an external AREF voltage.
Inside the main loop:

• The LDR is read using ADC channel A0 and classified into brightness levels

• The TMP36 is read using ADC channel A1

• Voltage is calculated from raw ADC values

• Temperature is converted into Celsius and Fahrenheit

• Data is printed to the serial terminal every second

The code avoids complexity and focuses on clarity, making it ideal for learning sensor interfacing.

Source Code

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/* Sensor test sketch
  for more information see http://www.ladyada.net/make/logshield/lighttemp.html
  */
 
#define aref_voltage 3.3         // we tie 3.3V to ARef and measure it with a multimeter!
 
int photocellPin = 0;     // the cell and 10K pulldown are connected to a0
int photocellReading;     // the analog reading from the analog resistor divider
 
//TMP36 Pin Variables
int tempPin = 1;        //the analog pin the TMP36's Vout (sense) pin is connected to
                        //the resolution is 10 mV / degree centigrade with a
                        //500 mV offset to allow for negative temperatures
int tempReading;        // the analog reading from the sensor

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Proteus Simulation

In Proteus, the circuit runs exactly like real hardware.
Adjusting the LDR light level changes the brightness classification, while modifying the TMP36 temperature value updates Celsius and Fahrenheit readings instantly.
The serial terminal displays continuous, readable sensor data, making debugging and learning straightforward.

FAQs

Conclusion

This project is a clean and practical introduction to sensor-based embedded systems using Proteus simulation.
It helps learners understand ADC usage, sensor voltage conversion, and serial communication in a real-world context.
Perfect for students and hobbyists, this project bridges the gap between theory and hands-on DIY electronics experimentation.

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Arduino Data Logger Shield & Sensor Test using ATmega328P with Proteus Simulation

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