Programmable number lock system

Programmable number lock system is a high security number lock system that can be used to lock electronic devices. The present system is very user friendly. This system is a combination of software and hardware at its best. We have used a 8051 microcontroller kit for interfacing our system.

In the present design we can activate or deactivate 9 devices. Each device is locked using a 4 digit code (password). The code can be set as per the user’s desire, hence the name ' PROGRAMMABLE '. For the device to be activated (unlocked), the user should enter the code that had been entered when the device was locked. In case the user enters the wrong code a silent alarm will be activated.


Introduction to Programmable number lock system:

The system has three units, namely:

( i ) Keyboard unit.

( ii ) Display unit.

( iii ) Control unit.

The keyboard unit consists of 9 number keys, 1 unlock key and 1 lock key. These are all push button switches. This unit is used to select the desired device and to enter the codes into the system. It is also used to request the system to lock/unlock the selected device.

The display section contains 5 seven segment display. This unit displays the device number and the code entered. This section is detachable. If detached it does not affect the working of the whole system. This unit also contains password reset button and an LED to indicate the error when the device is already locked and user wants to lock the device again. The error indicator also indicates an error when the system is already unlocked and the user tries to unlock the same.

The control unit is the heart of our system. It contains the necessary circuitry for the control of the device .This unit controls 9 devices, which is lock/unlock by selecting it using the keyboard and entering the password. If the code entered to unlock the device is wrong, then a silent alarm is triggered .The keyboard unit and the display unit are connected to this unit.

All these three units are merged together to form the whole system.





Block diagram of Programmable number lock system:




Working of the system:

When the system is initially installed the reset button is pressed. This key is present in the control unit. This unlocks all the devices. This is to avoid undesired functioning of the system.

To lock a particular device the device number is selected using the keyboard. Once the device is selected the user has to press the lock key present in the keyboard. Now the device waits for the user to enter the the code. The user can enter a 4 digit number using the keyboard as per his desire. Once all the 4 digits are entered the system electronically locks the selected device.

In the same manner to unlock a particular device, the device number is entered using the keyboard. Once the device number is selected the code for the selected device is entered. If the entered code matches the code that had been entered while that particular device was locked then the selected device will be activated (unlocked). If the codes do not match each other a silent alarm will be triggered (a LED placed in the control section. Shown in figure 3).An error indicator (placed in the display section) is provided if any user tries to lock a device which has already been locked or vice versa.

If the user is half way entering the code or has done an error while entering the code and wants to start over all again then a reset button is provided in the display section. By pressing this button the user can start from entering the device number and so on.

The number of devices which the system can control can be increased by addition of a few components in the control unit. More security can be achieved by increasing the number of digits in the code. This can be done by minor changes in the program. The system uses the internal RAM of the 8051 to store the code and hence puts a lower limit to the number of digits in the code and also the number of devices the system can control. Once the system is installed only the display unit and keyboard unit will be accessible to the user. Access to the control unit should be provided only to an official personal since it contains the system reset button.

System:

In this section we will be explaining the hardware design these units individually. Each unit description is accompanied by its circuit diagram.

KEYBOARD UNIT :

The keyboard used in this system is an encoder type. It uses IC 74147 priority encoder to convert the entered the digits to its corresponding binary codes. IC 74147 has a active low inputs as well as active low outputs (for more details please refer the corresponding data sheets). Each of the pins are activated using push to on switches. These switches ground the encoder inputs to activate that particular number giving the equivalent BCD code. This is then given as input to IC 7404 which is an inverter. To avoid loading of 7404 by the later stages transistor switches are provided to each of its outputs. The circuit diagram of the keyboard is as given in the next section.

DISPLAY UNIT :

The logic used here is shift and display i.e. when the next number is entered the previous number is shifted to the left by one unit and then the next number is displayed. To achieve this we have used IC 7496 which is a 5–bit shift register (for more details please refer the corresponding data sheets). The data lines from control section are given serially to the registers as shown in the circuit. The clock to these registers is given by the program every time a button on the keyboard is pressed. The shifting used here is parallel shifting. The outputs of the registers are given to CD4511 BCD to seven segment decoder. The seven segment display used are common cathode type since the output of the decoder is high when activated. This section consists of a reset switch which is used to reset the display.



Control Unit




APPLICATION:

The ‘Electronic device number lock’ system is a high security system.The main application kept in mind during the design of this system is to secure expensive electronic devices and machinery. The access to such devices can be restricted to particular users only. The system is highly secured since the code can be changed every time the user locks it.
This can also be used an physical lock by using solenoid and thus can be used to lock safes in banks or other institutions.
Regular electronic number lock available in the market can lock/unlock just one device, but this design can lock/unlock up to nine devices.

The program used for the operation of this system is as follows :

;***************************************************************;

PROCEDURE OF WAIT

;***************************************************************

org 8500h

wait: push dph

push dpl

push r0

push r1

mov dptr,#2042h ;input data from PORT C

wi: movx a,@dptr

mov r2,a

anl a,#20h

jz cont ;check for interrupt from display unit

jmp start

cont: mov a,r2

anl a,#0fh ;to check whether any key is pressed

jz wi

mov r0,#75

lcall 6798h

mov dptr,#2042h

here: movx a,@dptr ;wait for the key to be realesed

jnz here

mov dptr,#2040h ;sending a pulse to the display section

mov a,r2

movx @dptr,a

mov a,#00h

mov dptr,#2041h

movx @dptr,a

mov a,#40h

movx @dptr,a

mov a,r2

mov r0,#75

lcall 6798h

pop r1

pop r0

pop dpl

pop dph

ret



;***************************************************************;
STORING AND RETRIVING OF PASS WORD

;***************************************************************

org 8550h

scan: mov r0,#04h

mov dptr,#2042h

one: movx a,@dptr ;check for lock or unlock buttons

anl a,#0c0h

jz one

ret



lock: lcall wait ;storing of pass word in given location

mov @r1,a

inc r1

djnz r0,lock

lcall out

ret



unlock: clr 0ah

call wait

mov a,@r1

xrl a,r2 ;comparing the entered and the stored code

jz match

setb 0ah ;in case of mismatch set error bit

match: inc r1

djnz r0,unlock

jnb 0ah,go

mov a,#20h

push dptr

mov dptr,#2040h

movx @dptr,a

push r0

push r1

mov r0,#ffh

lcall 6798h

pop r1

pop r0

mov a,#00h

movx @dptr,a

pop dptr

jmp not

go: lcall out

not: ret





;***************************************************************;

TO ACCEPT THE DEVICE NUMBER

;***************************************************************

org 9000h

mov sp,#05fh

main: clr 01h ;clearing all the device flags

clr 02h

clr 03h

clr 04h

clr 05h

clr 06h

clr 07h

clr 08h

clr 09h

setb ie.7

setb ie.2

start: mov a,#89h ;C as i\p,A and B as o\p

mov dptr,#2043h

movx @dptr,a



mov r7,#05h ;clearing the display section

rss: mov dptr,#2040h

mov a,#00h

movx @dptr,a

mov a,#00h

mov dptr,#2041h

movx @dptr,a

mov a,#40h

movx @dptr,a

djnz r7,rss

lcall wait

cjne a,#01h,nxt2

jmp dev1

nxt2: cjne a,#02h,nxt3

jmp dev2

nxt3: cjne a,#03h,nxt4

jmp dev3

nxt4: cjne a,#04h,nxt5

jmp dev4

nxt5: cjne a,#05h,nxt6

jmp dev5

nxt6: cjne a,#06h,nxt7

jmp dev6

nxt7: cjne a,#07h,nxt8

jmp dev7

nxt8: cjne a,#08h,nxt9

jmp dev8

nxt9: cjne a,#09h,start

jmp dev9



;***************************************************************;

SELECTED DEVICE ACTIVATION

;***************************************************************

org 9200h

dev1: mov r1,#30h ;Loading the address of the password

mov r3,#01h ;device no. used to give to the decoder

lcall scan

cjne a,#80h,unlock1 ;check for the lock\unlock pressed

jmp lock1

unlock1: jnb 01h,error1 ;generating error if the selected device is already

;activated

lcall unlock

jb 0ah,hr1

clr 01h ;clear lock\unlock flag

hr1: jmp start

lock1: jb 01h,error1

lcall lock

setb 01h ;set lock\unlock flag

jmp start

error1: mov a,#40h ;activating the error LED

mov dptr,#2040h

movx @dptr,a

push dptr

push r0

push r1

mov r0,#ffh

lcall 6798h

pop r1

pop r0

pop dptr

jmp start



;***************************************************************

dev2: mov r1,#035h

mov r3,#02h

lcall scan

cjne a,#80h,unlock2

jmp lock2

unlock2: jnb 02h,error2

lcall unlock

jb 0ah,hr2

clr 02h

hr2: jmp start

lock2: jb 02h,error2

lcall lock

setb 02h

jmp start

error2: mov a,#40h

mov dptr,#2040h

movx @dptr,a

push dptr

push r0

push r1

mov r0,#ffh

lcall 6798h

pop r1

pop r0

pop dptr

jmp start



;***************************************************************

dev3: mov r1,#03ah

mov r3,#03h

lcall scan

cjne a,#80h,unlock3

jmp lock3

unlock3:jnb 03h,error3

lcall unlock

jb 0ah,hr3

clr 03h

hr3: jmp start

lock3:jb 03h,error3

lcall lock

setb 03h

jmp start

error3: mov a,#40h

mov dptr,#2040h

movx @dptr,a

push dptr

push r0

push r1

mov r0,#ffh

lcall 6798h

pop r1

pop r0

pop dptr

jmp start



;***************************************************************

dev4: mov r1,#040h

mov r3,#04

lcall scan

cjne a,#80h,unlock4

jmp lock4

unlock4:jnb 04h,error4

lcall unlock

jb 0ah,hr4

clr 04h

hr4: jmp start

lock4:jb 04h,error4

lcall lock

setb 04h

jmp start

error4: mov a,#40h

mov dptr,#2040h

movx @dptr,a

push dptr

push r0

push r1

mov r0,#ffh

lcall 6798h

pop r1

pop r0

pop dptr

jmp start



;***************************************************************

dev5: mov r1,#045h

mov r3,#05h

lcall scan

cjne a,#80h,unlock5

jmp lock5

unlock5:jnb 05h,error5

lcall unlock

jb 0ah,hr5

clr 05h

hr5: jmp start

lock5:jb 05h,error5

lcall lock

setb 05h

jmp start

error5: mov a,#40h

mov dptr,#2040h

movx @dptr,a

push dptr

push r0

push r1

mov r0,#ffh

lcall 6798h

pop r1

pop r0

pop dptr

jmp start



;***************************************************************

dev6: mov r1,#04ah

mov r3,#06h

lcall scan

cjne a,#80h,unlock6

jmp lock6

unlock6:jnb 06h,error6

lcall unlock

jb 0ah,hr6

clr 06h

hr6: jmp start

lock6:jb 06h,error6

lcall lock

setb 06h

jmp start

error6: mov a,#40h

mov dptr,#2040h

movx @dptr,a

push dptr

push r0

push r1

mov r0,#ffh

lcall 6798h

pop r1

pop r0

pop dptr

jmp start



;**************************************************************

dev7: mov r1,#050h

mov r3,#07h

lcall scan

cjne a,#80h,unlock7

jmp lock7

unlock7:jnb 07h,error7

lcall unlock

jb 0ah,hr7

clr 07h

hr7:jmp start

lock7:jb 07h,error7

lcall lock

setb 07h

jmp start

error7: mov a,#40h

mov dptr,#2040h

movx @dptr,a

push dptr

push r0

push r1

mov r0,#ffh

lcall 6798h

pop r1

pop r0

pop dptr

jmp start

;***********************************************************

dev8: mov r1,#055h

mov r3,#08h

lcall scan

cjne a,#80h,unlock8

jmp lock8

unlock8:jnb 08h,error8

lcall unlock

jb 0ah,hr8

clr 08h

hr8: jmp start

lock8:jb 08h,error8

lcall lock

setb 08h

jmp start

error8: mov a,#40h

mov dptr,#2040h

movx @dptr,a

push dptr

push r0

push r1

mov r0,#ffh

lcall 6798h

pop r1

pop r0

pop dptr

jmp start



;***********************************************************

dev9: mov r1,#05ah

mov r3,#09h

lcall scan

cjne a,#80h,unlock9

jmp lock9

unlock9:jnb 09h,error9

lcall unlock

jb 0ah,hr9

clr 09h

hr9: jmp start

lock9:jb 09h,error9

lcall lock

setb 09h

jmp start

error9: mov a,#40h

mov dptr,#2040h

movx @dptr,a

push dptr

push r0

push r1

mov r0,#ffh

lcall 6798h

pop r1

pop r0

pop dptr

jmp start

;***********************************************************

; OUTPUT SECTION

;***********************************************************

org 0a000h

out: mov a,r3 ;loading the device number

mov dptr,#2041h

movx @dptr,a

ret

;***********************************************************