19-03-2012, 03:48 PM
digital code lock
DIGITAL CODE LOCK.docx (Size: 735.65 KB / Downloads: 68)
INTRODUCTION
A digital code lock is a device which has a digital control assembly attached to it by using AT89C51 microcontroller. They are provided with an access control system. This system allows the user to unlock the device with a password. The password is entered by making use of a keypad. The user can also set his password to ensure better protection.
A 4x3 matrix keypad and a 16x2 LCD have been used here. Keypad and LCD are very commonly used input & output devices, respectively. A four digit predefined password needs to be specified the user. This password is stored in the system.
While unlocking, if the entered password from keypad matches with the stored password, then the lock opens and a message is displayed on LCD. Also an output pin is made high to be used for further purpose.
POWER SUPPLY
Power supply is used to give 5v regulated constant power to our microcontroller. The main supply is 230v AC which firstly passed through step down transformer. And then after bridge circuit convert it in to DC voltage. Then after voltage regulating IC7805 is used to take 5v constant.
Capacitors are joined parallel to circuit to provide more stable DC. And this section is connected to giving a 5v supply for Digital Code Lock.
MICROCONTROLLER MODULE
I have used AT89C51 IC in this project. And programming is done in assembly language. For assembly programming command prompt is used. And as based on password detector we can use it as security purpose.
The connections in the circuit are as following: port P3 of microcontroller AT89C51 is used as data input port which is connected to data pins (7-14) of LCD. P2.5, P2.6 and P2.7 pins of microcontroller are connected to control pins RS, RW and EN of LCD. Port P1.0/3 & p2.0/3 is used to take input from keypad.
As the program starts, string ‘Enter New Password’ is displayed on LCD. The keypad is scanned for pressed digits one by one. Every time, row and column of the key pressed is detected and digit is displayed on LCD corresponding to the entered number. After the four digits are entered, the user is prompted to ‘Enter Password’ and again the input is taken through LCD. If the passwords do not match, a message is displayed to indicate ‘Incorrect; otherwise the user is prompted to unlock the device.
To unlock, user needs to ‘Enter Password’ through keypad. Again the keypad is scanned for pressed keys and corresponding digits are identified. The passkey is displayed on the LCD screen. After the four digits are entered, they are compared with the pre-set password. If all the four digits match with set password, LCD displays ‘Hi Sir’ and the lock output pin goes high. If the security code is wrong, ‘Incorrect’ is sent to be displayed on LCD and give massage that, how much trial left. The system gets locked if more than three attempts are made with wrong password to open the electronic lock and ‘-CODE BLOCKED-‘massage will display on screen. The system needs to be reset in such a case.
REGULATING IC7805
The L78xx Series of fixed voltage regulators are designed with thermal overload protection that shuts down the circuit when subjected to an excessive power overload condition, internal short-circuit protection that limits the maximum current the circuit will pass, and output transistor safe-area compensation that reduces the output short-circuit current as the voltage across the pass transistor is increased. However, it is recommended that the regulator input be bypassed with capacitor if the regulator is connected to the power supply filter with long lengths, or if the output load capacitance is large. An input bypass capacitor should be selected to provide good high frequency characteristics to insure stable operation under all load conditions. A 0.33 μF or larger tantalum, Mylar or other capacitor having low internal impedance at high frequencies should be chosen. The bypass capacitor should be mounted with the shortest possible leads directly across the regulators input terminals. Normally good construction techniques should be used to minimize ground loops and lead resistance drops since the regulator has no external sense lead. The addition of an operational amplifier allows adjustment to higher or intermediate values while retaining regulation characteristics. The minimum voltage obtained with the arrangement is 2 V greater than the regulator voltage.
DIGITAL CODE LOCK.docx (Size: 735.65 KB / Downloads: 68)
INTRODUCTION
A digital code lock is a device which has a digital control assembly attached to it by using AT89C51 microcontroller. They are provided with an access control system. This system allows the user to unlock the device with a password. The password is entered by making use of a keypad. The user can also set his password to ensure better protection.
A 4x3 matrix keypad and a 16x2 LCD have been used here. Keypad and LCD are very commonly used input & output devices, respectively. A four digit predefined password needs to be specified the user. This password is stored in the system.
While unlocking, if the entered password from keypad matches with the stored password, then the lock opens and a message is displayed on LCD. Also an output pin is made high to be used for further purpose.
POWER SUPPLY
Power supply is used to give 5v regulated constant power to our microcontroller. The main supply is 230v AC which firstly passed through step down transformer. And then after bridge circuit convert it in to DC voltage. Then after voltage regulating IC7805 is used to take 5v constant.
Capacitors are joined parallel to circuit to provide more stable DC. And this section is connected to giving a 5v supply for Digital Code Lock.
MICROCONTROLLER MODULE
I have used AT89C51 IC in this project. And programming is done in assembly language. For assembly programming command prompt is used. And as based on password detector we can use it as security purpose.
The connections in the circuit are as following: port P3 of microcontroller AT89C51 is used as data input port which is connected to data pins (7-14) of LCD. P2.5, P2.6 and P2.7 pins of microcontroller are connected to control pins RS, RW and EN of LCD. Port P1.0/3 & p2.0/3 is used to take input from keypad.
As the program starts, string ‘Enter New Password’ is displayed on LCD. The keypad is scanned for pressed digits one by one. Every time, row and column of the key pressed is detected and digit is displayed on LCD corresponding to the entered number. After the four digits are entered, the user is prompted to ‘Enter Password’ and again the input is taken through LCD. If the passwords do not match, a message is displayed to indicate ‘Incorrect; otherwise the user is prompted to unlock the device.
To unlock, user needs to ‘Enter Password’ through keypad. Again the keypad is scanned for pressed keys and corresponding digits are identified. The passkey is displayed on the LCD screen. After the four digits are entered, they are compared with the pre-set password. If all the four digits match with set password, LCD displays ‘Hi Sir’ and the lock output pin goes high. If the security code is wrong, ‘Incorrect’ is sent to be displayed on LCD and give massage that, how much trial left. The system gets locked if more than three attempts are made with wrong password to open the electronic lock and ‘-CODE BLOCKED-‘massage will display on screen. The system needs to be reset in such a case.
REGULATING IC7805
The L78xx Series of fixed voltage regulators are designed with thermal overload protection that shuts down the circuit when subjected to an excessive power overload condition, internal short-circuit protection that limits the maximum current the circuit will pass, and output transistor safe-area compensation that reduces the output short-circuit current as the voltage across the pass transistor is increased. However, it is recommended that the regulator input be bypassed with capacitor if the regulator is connected to the power supply filter with long lengths, or if the output load capacitance is large. An input bypass capacitor should be selected to provide good high frequency characteristics to insure stable operation under all load conditions. A 0.33 μF or larger tantalum, Mylar or other capacitor having low internal impedance at high frequencies should be chosen. The bypass capacitor should be mounted with the shortest possible leads directly across the regulators input terminals. Normally good construction techniques should be used to minimize ground loops and lead resistance drops since the regulator has no external sense lead. The addition of an operational amplifier allows adjustment to higher or intermediate values while retaining regulation characteristics. The minimum voltage obtained with the arrangement is 2 V greater than the regulator voltage.