1. INTRODUCTION:
The mini project is” PASSWORD ACCESS USING UART”. The main theme of this project is accessing the password in pc using uart.
In this project we used the keyboard to control the uart. With the use of this keyboard we can access password easily with press of single key.
Security is a prime concern in our day-today life. Everyone wants to be as much
secure as possible. An access control for doors forms a vital link in a security chain. The
password based access control system is a digital lock for doors that allows only authorized persons to access a restricted area. The system is fully controlled by the 16-bit ATMEGAmicrocontroller. The four digit password is stored in the ARRAY external to the ATMEGA16. The system has a keypad by which the password can be entered through it. When the entered password equals with the password stored in the memory then the relay gets on and so that the door is opened. If we entered a wrong password for more than five times then the alarm is switched on.
The user can type the password issued to him and if the entered password is correct
the LCD displays “Access Granted; Door is open”. An LED glow indicates that the relay
used for opening the door goes on. For an incorrect password entry, LCD displays “Invalid Password; Try Again !!!”. If the entered password is wrong for five consecutive trials, an alarm starts to sound. Now only a reset can make the system to the initial state.
At the time of each successful login, the currently entered password and time will be
sent to a PC through UART interface. The hyper terminal displays this and the same PC can be converted to a server data base for storing the log file.
In this project we used the keyboard to control the uart. With the use of this keyboard we can access password easily with press of single key.
The user can type the password issued to him and if the entered password is correct
the LCD displays “Access Granted; Door is open”. An LED glow indicates that the relay
used for opening the door goes on. For an incorrect password entry, LCD displays “Invalid Password; Try Again !!!”. If the entered password is wrong for five consecutive trials, an alarm starts to sound. Now only a reset can make the system to the initial state.
2.COMPONENTS:
· Pc
· Programming cable
· At mega 16 l board
· AMS 1117 board
· UART board
· Resisters, capacitors
· Burk sheet pins
· Connecting wires
· 9 volts batteries
· Connecting wires
· Multi meter
3.UART
UniversalAsynchronousReceiver/Transmitter
UniversalAsynchronousReceiver/Transmitter (UART), to function properly. The UART chip takes the parallel output of the computer's system bus and transforms it into serial form for transmission through the serial port. In order to function faster, most UART chips have a built-in buffer of anywhere from 16 to 64 kilobytes. This buffer allows the chip to cache data coming in from the system bus while it is processing data going out to the serial port. While most standard serial ports have a maximum transfer rate of 115 Kbps (kilobits per second), high speed serial ports, such as Enhanced Serial Port (ESP) and Super Enhanced Serial Port (Super ESP), can reach data transfer rates of 460 Kbps.
3.1 UART interfacing
All computer operating systems in use today support serial ports, because serial ports have been around for decades. Parallel ports are a more recent invention and are much faster than serial ports. USB ports are only a few years old, and will likely replace both serial and parallel ports completely over the next several years.
The name "serial" comes from the fact that a serial port "serializes" data. That is, it takes a byte of data and transmits the 8 bits in the byte one at a time. The advantage is that a serial port needs only one wire to transmit the 8 bits (while a parallel port needs 8). The disadvantage is that it takes 8 times longer to transmit the data than it would if there were 8 wires. Serial ports lower cable costs and make cables smaller.
Before each byte of data, a serial port sends a start bit, which is a single bit with a value of 0. After each byte of data, it sends a stop bit to signal that the byte is complete. It may also send a parity bit.
Serial ports, also called communication (COM) ports, are bi-directional. Bi-directional communication allows each device to receive data as well as transmit it. Serial devices use different pins to receive and transmit data -- using the same pins would limit communication to half-duplex, meaning that information could only travel in one direction at a time. Using different pins allows for full-duplex communication, in which information can travel in both directions at once.
The Universal Asynchronous Receiver/Transmitter (UART) takes bytes of data and transmits the individual bits in a sequential fashion. At the destination, a second UART re-assembles the bits into complete bytes. Each UART contains a shift register which is the fundamental method of conversion between serial and parallel forms. Serial transmission of digital information (bits) through a single wire or other medium is much more cost effective than parallel transmission through multiple wires.
Here we use max232 IC board .
