Category Archives: PIC Projects


Calibrating a thermistor for temperature measurements

Posted on by Leave a comment

A thermistor is a passive device that changes its resistance with temperature. If the temperature-resistance characteristic is known, it can be used as a temperature sensor by measuring the resistance, or more precisely, the voltage across it. Thermistors are classified in to two types: NTC (negative temperature coefficient) and PTC (positive temperature coefficient). A NTC thermistor decreases its resistance while the temperature rises, and a PTC does the opposite. Although the datasheet of a thermistor describes the temperature-resistance relationship, the measurement based on that is not very accurate. Therefore, you may need to calibrate it against a more accurate sensor.

Read more

Single button code entry for a digital lock

Posted on by Leave a comment

Yes, it has got just one push button to enter the code to unlock the system. The author demonstrates how you can just enter multiple code numbers in sequence from a single button input. If the code entered matches with the preset pass code, a relay is turned on. This project uses a PIC16F628A microcontroller that monitors the user inputs from the single button. You can enter a number 3 by pressing the button 3 times. Every time you enter a number, the microcontroller acknowledges by lighting an LED. When you entered all the code numbers correctly in sequence, the

Read more

A Digital temperature meter using an LM35 temperature sensor

Posted on by 84 comments

Introduction A digital thermometer is a good choice of project for beginners who just stepped in to the world of microcontrollers because it provides an opportunity to learn using sensors to measure the real world signals that are analog in nature. This article describes a similar project based on a PIC16F688 microcontroller and an LM35 temperature sensor. LM35 is an analog sensor that converts the surrounding temperature to a proportional analog voltage. The output from the sensor is connected to one of the ADC channel inputs of the PIC16F688 microcontroller to derive the equivalent temperature value in digital format. The

Read more

Microcontroller based Diode and Bipolar Junction Transistor (BJT) tester

Posted on by 32 comments

Introduction Most of the digital multimeters these days have built-in features for testing diodes and sometimes transistors. The purpose of this project is to demonstrate a simple way to construct a testing device for diodes and bipolar junction transitors (BJTs) using a microcontroller. The testing algorithm is based on a simple fact that a working PN junction conducts current in only one direction. A PIC16F688 microcontroller is used in this project that switches the bias voltage across the PN junctions of diode and transistors, and determines if a particular junction is normal, open or short. Theory The logic behind testing

Read more

Lab 3: Four bit binary counter

Posted on by 5 comments

Description Today’s lab session is about binary counting LEDs. The binary 1 and 0 will be represented by turning LEDs on and off. You will make a 4-bit binary counter (using 4 LEDs) that counts from 0 to 15 (0000-1111 binary). The four LEDs are connected to RC0 through RC3 port pins of PIC16F688 with current limiting resistors (470? each) in series. A push button switch is connected to pin RC4 to provide input for the counter. The counter starts from 0, and increase by 1 every time the button is pressed. When the counter reaches 15 (all LEDs on),

Read more
« Older Entries Recent Entries »