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microcontroller

AVR Microcontroller

Written By: 
Akshay Daga

There are number of popular families of microcontrollers which are used in different applications as per their capability and feasibility to perform the desired task, mostAVR Microcontroller common of these are 8051, AVR and PIC microcontrollers. This article introduces the AVR family of microcontrollers.

AVR was developed in the year 1996 by Atmel Corporation. AVR is an 8-bit microcontroller belonging to the family of Reduced Instruction Set Computer (RISC). In RISC architecture the instruction set of the computer are not only fewer in number but also simpler and faster in operation.

Interrupts & Programming 8051 Hardware Interrupts

Written By: 
Himanshu Choudhary
 

How to interface GSM Module with 8051 microcontroller (AT89C51) using PC

GSM is widely used mobile communication architecture used in most of the countries. This project demonstrates the interfacing of [[wysiwyg_imageupload::]]microcontroller AT89C51 with HyperTerminal and GSM module. It aims to familiarize with the syntax of AT Commands and their Information Response and Result Codes. The ASCII values of characters in the Information Response, Result Codes and their syntax can be monitored by an LED array. For the basic concepts, working and operation of AT commands and GSM module refer GSM/GPRS Module. The project explains interfacing of the AT89C51 microcontroller with the GSM module and the HyperTerminal. HyperTerminal is a Windows application. TheAT commands are sent by the HyperTerminal to the GSM module. The Information Response and/or Result Codes are received at the microcontroller and retransmitted to the HyperTerminal by the controller. Read on to understand how does this circuit work and how its microcontroller can be programmed. 

How to interface GSM Module with 8051 microcontroller (AT89C51) using PC and LCD

This project is an extension of interfacing microcontroller with hyperterminal and GSM module. The previous project explained a way to interface a GSM [[wysiwyg_imageupload::]]module with 8051 microcontroller where the information response and result codes received by the controller were sent back to computer to display them at HyperTerminal. In this project, the same output is displayed on a 16x2 LCD interface. This project is first step towards making and independent system using the GSM module and a microcontroller. Here the HyperTerminal (computer) has been replaced with LCD at the output end. In the next project (MC076), the AT Commands will be transmitted to the GSM module by the microcontroller itself thus avoiding the need of using HyperTerminal entirely. This project adds a feature to display the information response and result codes on a 16x2 LCD in response to the AT commands sent through the HyperTerminal of computer. The characters typed at HyperTerminal get transmitted serially through the transmit pin (Tx) of RS232 interface. 

Timers & 8051 Timer Programming

Written By: 
Himanshu Choudhary

 

EEPROM (24C02) Memory Reset using 8051 microcontroller (AT89C51)

AT24C02 is two-wire serially programmable EEPROM. This means that for programming, the data and control signals are provided serially along with clock Memory Reset signals from the other wire. The read-write operations are accomplished by sending a set of control signals including the address and/or data bits from a microcontrollerThis project demonstrates the memory reset operation of a 24C02 IC by using AT89C51. For basic operations of AT24C02, refer interfacing serial EEPROM with 8051. It writes & reads a byte to/from the EEPROM displaying it on a 16x2 LCD, and then resets the memory. The results can be monitored on the LCD display.

AT24C02 is a two-wire serial EEPROM from Atmel. 24C02 is an 8 pin IC and reads 8 bit data serially. Its memory size is 2KB. Pins 1- 3 are address pins which are connected to ground. Pin 4 is GND; Pin 5 is SDA (serial data); and pin 6 is SCL (serial clock input). Pin 7 is WP (write protect) pin and is connected to GND. Pin 8 is Vcc for providing power supply. 

How to Interface Serial EEPROM 24C02 with 8051 microcontroller (AT89C51)

 

EEPROM stands for electrically erasable programmable read only memory. It is a secondary storage device that once written (programmed) can hold data even [[wysiwyg_imageupload::]]when the power is removed. The EEPROM is a class of read only memory that can be electrically erased and reprogrammed.

AT24C02 is a two wire 2Kbits serial EEPROM by Atmel. The memory is organized in 256 words of single byte each arranged in 32 pages of 8 bytes each. The addressing of memory locations requires eight bit addresses.

AT24C02 is two-wire serially programmable i.e., for programming, the data and control signals are provided serially along with clock signals from the other wire. The read-write operations are accomplished by sending a set of control signals including the address and/or data bits. The control signals must be accompanied with proper clock signals.

The AT24C02 has hard wire addressing of 3 bit length. This facilitates interfacing of a maximum of eight (23) 24C02 devices to a system thereby, incorporating a maximum 16Kbits memory. Multiple 24C02 devices can be connected to a microcontroller/microprocessor based system using I2C interface.

Toll plaza system based on vehicle category interface with 8051 microcontroller (AT89C51)

 

This topic is an extension to Simple toll plaza system. The toll amount is charged based on the category of the vehicle driving through the plaza. The vehicle Toll plaza system based on vehicle category interface with 8051 microcontroller (AT89C51) categories taken here are two-wheeler & four-wheeler. When a user scans his ID at the toll plaza, some amount is charged from his account depending upon his vehicle category. User also has the facility to recharge his account.

The project has been developed by interfacing RFID with AT89C51. The relevant messages are also displayed on a 16x2 LCD. The free source code for the program is available in C.

Simple toll plaza system charges the toll tax from the user irrespective of the type of his vehicle. This project also considers the vehicle type while charging the toll amount. The RFID tag is used as a unique identity for account of a particular user.

 When a vehicle drives through the toll plaza, its driver is prompted to scan his RFID tag. If the identity (serial number of the tag, i.e., 12 byte data) is matched with the one already stored in the system, the toll amount is deducted from his account. After this, the vehicle gets immediate access to drive through. All the features of the Simple toll plaza system are also provided in this project by interfacing RFID with AT89C51.

Simple toll plaza system using low frequency RFID interfaced with 8051 microcontroller (AT89C51)

 

Electronic/automated toll collection systems are very popular these days. They do not require manual collection and operation of toll barriers.  The details about [[wysiwyg_imageupload::]]the vehicles and payment are stored in an RFID based system.

This article explains the working of a simple toll plaza system interfaced with RFID. Each user holds a unique ID for his vehicle. When the user scans his tag while passing through the plaza, a certain amount is deducted from his account. A user may also recharge his account in case of insufficient balance. The project has been developed by interfacing RFID with AT89C51. The relevant messages are also displayed on a 16x2 LCD. The free source code for the program is available in C.

Low frequency RFID work at 125 KHz frequency with radio waves. There is a coil inside the RFID tag and when it is influenced by a magnetic field, it sends a 12 byte identity code to RFID reader for further processing.  The RFID tag is used as a unique identity for account of a particular user. When a vehicle drives through the toll plaza, its driver is prompted to scan his RFID tag. If the identity (serial number of the tag, i.e., 12 byte data) is matched with the one already stored in the system, the toll amount is deducted from his account. After this, the vehicle gets immediate access to drive through.

Interfacing RFID with 8051 microcontroller (AT89C51) using serial interrupt

 

This topic covers the interfacing of RFID system with microcontroller through serial interrupt. An RFID system consists of a reader device and a Interfacing RFID with 8051 transponder. A transponder or tag has a unique serial number which is identified by the reader. RFID tag is applied to products, individuals or animals to identify and track them through this number.

The interfacing has been done through AT89C51. The identification code of the tag is also displayed on a 16x2 LCD. The free source code for the program is available in C.

The RFID system interfaced with AT89C51 requires the controller to continuously scan the input from the RFID reader. In this topic, the program has been made more efficient by incorporating a serial interrupt.

Different RFID tags work on different frequencies. Here low frequency, 125 kHz, RFID tags have been used. These tags work within a range of 10 cm. When an RFID tag comes in this range, the reader detects it and sends a unique code of the tag serially. This serial code, consisting of 12 bytes, is received by the microcontroller.

In the program, Timer1 is configured for serial communication. (Refer Timer programming in 8051) The baud rate is set to 9600bps for data transmission. The LCD is initialized to display the code. When a card/tag comes in the proximity of RFID reader, the microcontroller reads the code and sends it to the LCD module.

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