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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.

How to interface RFID with 8051 microcontroller (AT89C51)

 

An RFID (Radio-frequency identification and detection) reader is a device which is used to communicate with RFID tags by receiving and transmitting signals. Interface RFID with 8051 These signals use radio waves for wireless communication. RFID tag is applied to products, individuals or animals to identify and track them. The identification is done through a unique serial number. This topic covers the interfacing of a passive RFID system with AT89C51. The code of RFID tag is also displayed on an LCD interface. The free source code for the program is available in C. An RFID module basically consists of two parts, namely, a tag and a reader. A typical RFID system consists of an antenna, a transceiver and a transponder (RF tag). The radio frequency is read by the transceiver and the information is transferred to a device for further processing. The information (the unique serial number) to be transmitted is stored in the RF tag or transponder. The transponder contains a chip and an antenna mounted on a substrate. The chip transmits the relevant information through antenna. 

Microcontrollers

Written By: 
RoseMary

A microcontroller is a small and low-cost computer built for the purpose of dealing with specific tasks, such as displaying information in a microwave LED or receiving information from a television’s remote control. MicrocontrollerMicrocontrollers are mainly used in products that require a degree of control to be exerted by the user.

Microcontroller has an input device in order to get the input and an output device (such as LED or LCD Display) to exhibit the final process.  The architecture of a microcontroller depends on the application it is built for. For example, some designs include usage of more than one RAM, ROM and I/O functionality integrated into the package.

Digital clock using DS12C887 and 8051 microcontroller (AT89C51) in 12 hour mode

This article is an improved version of LCD based clock using RTC DS12C887 and 8051 microcontroller (AT89C51) using update interrupt. DS12C887 has two modes Clock Using RTC of operation i.e., 12 hour and 24 hour mode. In our earlier articles we explained how to use 24 hour mode. This article explores how we can use the 12 hour mode of RTC. This is done by making a clock using RTC and 8051 microcontroller (AT89C51) with 12 hour mode operation. The clock time is displayed on a 16x2 LCD interface. The free source code for the program is available in C.

Port P2 is used as data port for LCD while port P0 of the microcontroller AT89C51 is used as data port for the RTC DS12C887. The pins P1^0 - P1^7 of the microcontroller are configured as reset, rs, rw, e, dig_hr1, dig_min1, start, setmode, am_pm pins respectively.

Clock using RTC DS12C887 & 8051 microcontroller (AT89C51) with alarm set function

 

DS12C887 is a real time clock (RTC) IC from Dallas Semiconductors. The RTCs provide precise time and date information. This article explains the making of a [[wysiwyg_imageupload::]]digital clock with alarm setting functionalities. RTC has been interfaced with AT89C51 to perform desired operations. This project is an improvement over Digital clock using RTC DS12C887 and 8051 microcontroller (AT89C51) with time set and has the alarm setting function also. The alarm setting function allows user to set the alarm. The clock time is displayed on the LCD.  The free source code for the program is available in C.

The circuit for interfacing the RTC and 16x2 LCD with the microcontroller 8051 is shown in the circuit diagram. Port P2 is set as data port for LCD to send the data on the LCD while port P0 is set as data port for the RTC DS12C887

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