Latest Microcontroller Based Electronic Project Circuits in 2014

A microcontroller is a small computer on a single integrated chip that is programmed to control the devices. Most of the embedded-based projects require knowledge about programming the microcontroller. Once students get an idea about the circuit, schematics and their operations, it becomes really easy to program a microcontroller.

This article provides a list of simple microcontroller-based electronic project circuits.

1. Biometric Fingerprint Based Security System

A biometric security system can recognize a person based on their fingerprint and uses a fingerprint scanner for the same. Traditional security systems can be inconvenient and time consuming and sometimes even error prone. The biometric-security systems are most secure and accurate than the traditional password security systems, and can be used at many places like industries, offices, collages, etc.

The process involves taking the image of the fingerprint and processing the stored image to get the data, and then comparing this data with the existing information in the database.

Circuit Diagram

Biometric Fingerprint circuit Based Security System

Hardware Components

• Fingerprint sensor
• Microcontroller
• LCD display
• Buzzer
• Keyboard
• Resistors
• Capacitors
• Transistors

Circuit Connections

• This electronic project circuit is constructed with a fingerprint module, an LCD, a Buzzer, a relay and switches.
• The fingerprint scanner is a 4-pin device with VCC, TX, RX and Ground pins. It is connected to pins 10, 11, 16 of the microcontroller.
• The LCD is an output device interfaced to the PORT0 pins of the microcontroller.
• A buzzer is connected to the pin number 24 of the microcontroller through a transistor.
• The switches are input devices interfaced to input pins: 1, 2, and 3 of the microcontroller. The relay is connected to the pin 25 of the microcontroller through a relay driver IC.

Circuit Explanation

• The 230v AC voltage is converted into a 12v AC with the help of a step-down transformer and the 12v AC is converted to a 12v DC with the help of the rectifiers to drive the circuit.
• The microcontroller develops the output logic signals and the load (DC motor) is switched on and off.
• The fingerprint scanner gives high and low-logic signals at the input of the microcontroller. The microcontroller is programmed to transfer the data to be displayed on the microcontroller, and also generates the corresponding output signal.
• When the microcontroller output pin goes high, the transistor conducts, and the relay coil is energized. This drives the DC motor to rotation in the forward and backward direction.

2. GSM-based Highway Vehicle Monitoring System

The vehicle monitoring system is designed for tracking the location or geographical position of any vehicle on the highways by using GPS navigation system and GSM features.The GSM modem and GPS receiver are both interfaced to 8051 microcontroller. The GPS modem gets the longitude and latitude data, indicating the position of the vehicle, and the GSM modem sends this data to the concerned authority.

Upon receiving a request from a user to the modem, the system sends the information about the position of the vehicle in terms of longitude and latitude.

Circuit Diagram

Vehicle Monitoring System

Hardware Components

• LCD
• GSM Modem
• GPS receiver
• Max-232
• Microcontroller 8051 family
• Flash Memory
• Resistors
• Capacitors
• Crystal

Circuit Connections

• The transmitter (Tx) and receiver (Rx) pins of the GSM modem are connected to the microcontroller port pins 10 and 11, respectively.
• LCD display is interfaced to the port 0 pins of the microcontroller.
• The flash device is connected to the 24 and 25 pins of the microcontroller.

Circuit Explanation

• The GPS receiver of the circuit receives the longitude and latitude information from the satellites.
• The microcontroller receives the location information from the GPS receiver.
• The microcontroller is programmed in order to send the location information to the GSM modem.
• The GSM modem transmits this information to the concerned authority.

3. RFID-based Electronic Toll Plaza System

These days electronic toll plaza system is fast replacing the traditional toll plaza system that involves manual force for toll collection. The advanced system consists of a RFID system that stores the details about the payment and vehicles.

The user ID card, which is also an RFID tag is scanned through the reader and the information present in the card, is accordingly processed, i.e., the toll amount is deducted from the account of the user.

Circuit Diagram

Electronic Toll plaza system

Hardware Components

• LCD display
• Max-232
• Resistors
• Capacitors
• Microcontroller
• RFID sensor

Circuit Connections

• The LCD is interfaced with the help of the pull-up resistors at PORT0 pins of the microcontroller 8051.
• The RFID sensor is interfaced to the pins 10 and 11 of the microcontroller through a max-232 dev.
• The crystal circuit is connected to the pins 18 and 19 of the microcontroller.

Circuit Explanation

• The RFID tag consisting of the user information and account details is swiped on the RFID reader.
• The RFID reader receives the information from the tag in the form of a 12-bit serial data.
• The serial data is fed to the microcontroller through the Max-232.
• The microcontroller is programmed in order to process the received data and display the processed result on the LCD display.

4. Quiz Buzzer Using Microcontroller

Quiz Buzzer systems are commonly used in schools and colleges during competitions. The process involves giving priority to the person who presses the buzzer at the earliest. However, the problem arises with the conventional buzzer systems if the buttons are pressed simultaneously by two or more persons. In such cases, it is difficult to make a choice, and sometimes the decision can be biased with the human intervention.

The quiz-buzzer system proposed here consists of 8 switches corresponding to eight teams. The output is displayed on the 7-segment display. The buzzer is also devised to give an alarm sound for an infinitesimally small duration of time.

Circuit Diagram

Quick Buzzer circuit

Hardware Components

• Switches
• Seven-segment display
• Microcontroller
• Speaker
• Resistors
• Capacitors
• Crystal

Circuit Connections

• The 8-push button switches are connected to the PORT1 of the microcontroller.
• The speaker is connected to the pin 32 of the microcontroller.
• The seven-segment display is connected to the PORT2 pins of the microcontroller.
• The 11.0952 MHz crystal is interfaced to the pins 18 and 19 of the microcontroller.

Circuit Explanation

• When any of the switch or any two switches are pressed, the microcontroller input pins receive a low-logic signal.
• The microcontroller is programmed in order to display the corresponding number of the switch on the 7-segment display, based on the timer values.
• At the same time, microcontroller is also programmed in order to give signals to ring the buzzer.

5. Electronic Token Number Display

The electronic token-number-display system is designed to eliminate the problems of conventional queue system that is quite time consuming and inconvenient. Each person is assigned a token number and once their token is displayed, the person is supposed to get the task done.

This system is used mainly in banks, hospitals, restaurants and many other public places.The system requires the user to type the number on the keyboard and press the button in order for the number to be displayed on the LCD screen.

It is possible to serially increment and decrease the numbers from the present number. A short duration of sound is buzzed for every changing of a number.

Circuit Diagram

Electronic Token Number Display

Hardware Components

• LCD display
• Crystal
• Capacitors
• Max-232
• Resistors
• 8051 microcontroller

Circuit Connections

• The LCD display is interfaced to the PORT0 pins of the microcontroller.
• The max-232 is connected to the pins 10 and 11 of the microcontroller.
• The crystal oscillator is interfaced to the pins 18, 19 of the microcontroller.

Circuit Explanation

• The serial data from the computer is sent to the microcontroller through the Max 232.
• The microcontroller is programmed in order to display the data or the token number on the LCD screen.
• The serial port of the microcontroller is connected to the PC and incoming and outgoing data is monitored using a software that is a serial window.
• The user can send the data from the PC HyperTerminal to the microcontroller serial port though a serial cable.
• Once the task is completed, button corresponding to the next token number is pressed and the above process is repeated.
• The data is incremented and decremented using a computer key board.

6. Electronic Code Lock with a User-defined Password

The electronic lock is a device with a control assembly to control the lock by a password. The password is entered from a key board. A user can also set his password to ensure better protection.

A 4 by 3 matrix keypad and a 16 by 2 LCD display are used here. A four-digit predefined password needs to be specified by the user. The password is then stored in the system. While unlocking, if the entered password from the keypad matches with the stored password, then the lock opens and a message is displayed on the LCD.

Circuit Diagram

Electronic code Lock system

Hardware Components

• 4*4 keypad
• LCD display
• Resistors
• Capacitors
• Crystal

Circuit Connections

• The PORT2 of the microcontroller is used as a data-input port, and is connected to the data pins of the LCD.
• The RS, RW and EN pins of the LCD are connected to the P2.0, P2.1, and P2.2 pins of the microcontroller.
• The 4*4 matrix keypad is interfaced to the PORT1 of the microcontroller.
• The crystal circuit is connected to the pins 18, 19 of the microcontroller.

Circuit Explanation

• The input is fed to the microcontroller from the keypad.
• The microcontroller is programmed to compare the input data received with an already stored data.
• If the input data matches the stored data, the microcontroller output pin goes high, i.e., a high logic output is obtained from the microcontroller to the LCD module.
• The LCD screen displays the “Lock open” message.
• If the entered data doesn’t match the stored data, the microcontroller output pin goes low and a message ‘Wrong Password’ is printed on the LCD screen.

7. Sensor-Based Digital Monitoring and Controlling of the Power Transformer

This project is designed to protect a power transformer from burning due to over load, over temperature, and input high voltage. It ensures that the power transformer is working in a smooth condition.

An LCD and a temperature sensor are interfaced to the microcontroller. The microcontroller is programmed in order to monitor each parameter’s values and display them on the LCD screen and protect the transformer by implementing a control action. For instance, if the transformer temperature increases more than the required value, then the controller disconnects the load.

Circuit Diagram

Digital monitoring system

Hardware Components

• Temperature sensor
• Relay
• LCD display
• Transformers
• Resistors
• Capacitors
• Buzzer
• Transistors
• Crystal

Circuit Connections

• This electronic project circuit consists of three main circuit blocks: a temperature circuit block, a current sensing circuit block, and a voltage sensing circuit block, which give analog inputs to the microcontroller.
• The temperatures sensing circuit interfaced to the pin number 2 of the microcontroller. The voltage sensing circuit output is connected to the input pin 4 of the microcontroller.
• The current sensing circuit output is connected to the pin 3 of the microcontroller.
• The LCD is interfaced to the microcontroller using pins numbered from 21 to 27.
• The buzzer is connected to the 15th pin of the microcontroller. The crystal circuit is interfaced to the microcontroller at pins 9 and 10.

Circuit Explanation

• Input from each sensor is given to the microcontroller.
• The microcontroller is programmed in order to compare the sensor inputs with the stored values in the database.
• If the stored value exceeds the input value, the microcontroller output pin goes high.
• The transistor is driven to conduction and acts as a switch that connects one terminal of the buzzer to the ground.
• The buzzer gets the supply and starts ringing.
• The normal and exceeding parameter values are displayed on the LCD screen.

8. Servo Motor Control through a Keypad

The project is designed to control a servo motor through a key pad. The servo motor is a small motor that we can accurately position at any angle. It contains internal circuits that automatically maintain that particular angle.

The servomotor receives input pulses from the microcontroller and starts rotating. The desired angle of the rotation is provided through a keypad matrix to the microcontroller. An LCD screen displays the angle of rotation entered by the user.

Circuit Diagram

Servomotor control system

Hardware Components

• Microcontroller
• 4*4 matrix key pad
• Relay
• Servomotor
• Resistors
• Capacitors

Circuit Connections

• The microcontroller PORT0 is used as data input port, which is connected to the data pins of the LCD.
• The RS, RW and EN pins of the LCD are connected to the P2.0, P2.1, and P2.2 pins of the microcontroller.
• The 4*4 matrix key pad is interfaced to the PORT1 of the microcontroller. The crystal circuit is interfaced to the pins 18 and 19 of the microcontroller.
• The relay is interfaced to the pins 23 and 24 of the microcontroller.

Circuit Explanation

• When the electronic project circuit is switched on, the LCD prompts the user to enter the angle of rotation.
• The user enters the angle in degrees from the keypad. The angle entered by the user is also displayed on the LCD display.
• The microcontroller is programmed for a fixed time delay. The input from the keypad is fed to the input of the microcontroller.
• The microcontroller recognizes that data and releases corresponding pulses to drive the servomotors.

So, these are the simplest, yet interesting electronic project circuits to be implemented using a microcontroller. All a student or a hobbyist needs to have is, the knowledge of circuit designing and microcontroller programming.

We hope this article will help the readers to get an idea for developing their own projects. Furthermore, we would feel glad if you find these embedded system projects worth to be implemented and choose any one. Please don’t forget to mention your choice, and also your feedback about this article in the comment section below.