DIY Electronic Project: Creating a Simple Temperature Logger with the PIC16F628A-I/P
Microcontrollers have revolutionized the world of DIY electronics, offering a compact and powerful way to control various aspects of a project. Today, we’ll explore how to build a simple temperature logger using the PIC16F628A-I/P, a popular 8-bit microcontroller from Microchip Technology. This project will introduce you to basic microcontroller programming and sensor interfacing, resulting in a functional temperature logger.

What is the PIC16F628A-I/P?
The PIC16F628A-I/P is an 8-bit microcontroller that offers 1k words of Flash program memory, 64 bytes of SRAM, and 128 bytes of EEPROM. It features a 16-bit timer, a 10-bit ADC (Analog-to-Digital Converter), and a range of I/O pins, making it ideal for small to medium complexity projects. Its ease of use and extensive support make it a great choice for beginners and hobbyists.

Components and Tools Needed
Before starting the project, gather the following components and tools:

PIC16F628A-I/P Microcontroller – The core of the project.
LM35 Temperature Sensor – To measure temperature.
16x2 LCD Display – For displaying temperature readings.
Resistors (various values) – For pull-ups and current limiting.
Capacitors (10µF, 100nF) – For power stabilization and filtering.
Breadboard and Jumper Wires – For prototyping.
Power Supply – Typically 5V DC.
Programmer – For programming the PIC16F628A-I/P.
Software – MPLAB X IDE and XC8 Compiler.
Building the Circuit
Prepare the Breadboard: Place the PIC16F628A-I/P on the breadboard. Ensure there's enough space for connections.

Connect the Power Supply: Connect the VDD (pin 14) to the positive terminal of your power supply (5V) and VSS (pin 5) to ground. Add a 10µF capacitor between VDD and VSS to stabilize the power supply.

Set Up the Temperature Sensor: Connect the LM35 temperature sensor to the microcontroller. The LM35 has three pins: VCC (to +5V), GND (to ground), and VOUT (which outputs the temperature in millivolts). Connect VOUT to the AN0 pin (RA0) of the PIC16F628A-I/P for analog-to-digital conversion.

Connect the LCD Display: Interface the 16x2 LCD to the microcontroller for displaying temperature readings. Connect the LCD’s VSS pin to ground, VCC to +5V, and the V0 pin to a potentiometer (10kΩ) for contrast adjustment. Connect RS and E pins of the LCD to GP0 and GP1 of the PIC16F628A-I/P, respectively. Connect the data pins D4 to D7 to GP2 to GP5 of the microcontroller.

Add Pull-Up Resistors: Place 10kΩ resistors between the microcontroller’s MCLR pin (pin 4) and +5V to ensure proper reset operation.

Programming the Microcontroller
Write the Code: Using MPLAB X IDE and XC8 Compiler, write a program to read analog values from the LM35 and convert them to temperature readings. The code will also handle displaying these readings on the LCD.

Program the PIC16F628A-I/P: Connect the microcontroller to the programmer and upload the code.

Testing and Calibration
Once programmed, power up the circuit. The LCD should display the temperature read from the LM35. Adjust the contrast using the potentiometer if necessary. Verify the temperature readings by comparing them to a known thermometer to ensure accuracy.

Conclusion
Creating a temperature logger with the PIC16F628A-I/P is an excellent way to get hands-on experience with microcontrollers, analog-to-digital conversion, and LCD interfacing. This project not only provides a practical tool for monitoring temperature but also introduces you to fundamental concepts in embedded systems. As you build and test your temperature logger, you’ll gain valuable skills that can be applied to more complex projects in the future. So, gather your components, fire up MPLAB X IDE, and start logging temperatures with your DIY creation!
www.utsource.net