HOME SECURITY DOCUMENTATION
Shane Millham and Justin Sangiorgi
ALARM
ACTIVE
CALL
DA COPZ
BACK
DOOR
FRONT
DOOR
TITLE PAGE
GARAGE
CLOSING
UPSTAIRS
WINDOWS
DOWNSTAIRS
WINDOWS
COUNT
DOWN
GARAGE
OPENING
CODE
CLOCK
CODE
DATA
CORRECT
CODE
HIDDEN
ACTIVATE
LEAVING
DEACTIVATE
PG1
HOME SECURITY DOCUMENTATION
Shane Millham and Justin Sangiorgi
OVERVIEW
In this project, we were instructed to design a model of a home security system. This system
simulates a house with two doors connecting outside, and two ground floor windows that could
be opened from the outside. If any of these are opened while the alarm is active, the alarm will
set off and the police will be called. Outside of the house, there is one button and one switch.
These control the code for the alarm. When the correct code is input into the system, the garage
door will open., And the alarm system will deactivate. While deactive, you can open any
windows and doors. You can also keep the upstairs windows open even once you reset the
system. Hitting the reset button inside the house will close the garage door, and reactivate the
alarm. To leave the house, you hit the leaving button, which gives you 5 seconds to leave the
house before the system rearms.
OVERVIEW
PG2
HOME SECURITY DOCUMENTATION
Shane Millham and Justin Sangiorgi
4 BIT SHIFT REGISTER FOR CODE
The alarm is deactivated by inputting a 4 bit code. The way you input the code is by using the
button and the switch. The 4 bit data is saved through a synchronous, positive edge triggered, 4
bit shift register. The shift register is used with 4 D flip flops. These D flip flops are preset low.
The four D flip flops are set up next to each other, in the order D, C, B, A. Flip flop D’s d is
connected to the switch, which acts as a data line in order to clock a high or low bit. When the
switch is positioned upwards, it is connected to VCC, so it is high. When the switch is
positioned downwards, it is connected to ground, so it is low. D’s Q is connected to C’s d, and
the cycle continues all the way down to flip flop A. The push button is used as a clock, so it is
connected to all of the clock inputs for the shift register. Hitting the button makes the clock go
high, which clocks in the data.
MOD 5 COUNTER FOR MULTIPLEXER AND CODE
The shift register then inputs the data into a 16:1 multiplexor. The multiplexor compares the
inputted data to the wanted data. In our security system we chose the value to be four (0100). If
the code is correct the mux will output a 1 on the 4th clock cycle from the 4th clock “and”, and
the door will open and the alarm will not sound. However if the code is inputted incorrectly the
mux outputs a 0 which starts the alarm sequence. Along with this multiplexor and shift register
is a mod 5 counter. The counter is connected directly to the clock which has it count every time
the clock is hit. On the fifth clock cycle the counter and the code are reset which clears the data.
CODE SYMBOL
PG3
HOME SECURITY DOCUMENTATION
Shane Millham and Justin Sangiorgi
8 BIT COUNTER
The counter consists mainly of three “D” flip flops and a 3:8 decoder. The counter gets enabled
when enable counter goes high. This occurs the first time the counter gets clocked when a full 4
bit code is inputted incorrectly into the alarm system. On the 5th clock a 1 is clocked into a D
flip flop counter. After the code is inputted incorrectly 3 times the decoder will enable the
alarm. This allows the burglar or the drunk homeowner to get 3 tries before the alarm goes off.
If at any point during the 3 tries the code is inputted correctly the door is opened and the
counter is reset. If the person gets the code correct after the 3rd try the door will open but the
alarm will remain enabled.
The counter starts at zero before it is clocked. After the first clock the counter goes to eight and
starts counting down. When the counter counts to six “3TRIES0” goes low and the alarm is
enabled. This is when you realize that you should have had a few less drinks at the party last
night.
COUNTER SYMBOL
PG4
HOME SECURITY DOCUMENTATION
Shane Millham and Justin Sangiorgi
MOD 14 TIMER
When the 8 bit counter is enabled the alarm system also enables a enables a 14 second timer.
The timer is made up of four D flip flops and a 26 bit LPM counter. The 26 bit LPM counter
converts the 50 HZ on board clock down to about 1 HZ which is 1 second. Approximately
every second the asynchronous modulus 14 counter is clocked. After 14 clock cycles the alarm
is enabled because “14SEC0” goes low. If the correct code is put in the timer will reset, stop,
and the door will open. If the correct code is inputted after 14 seconds the door will open but
the alarm will continue to run until reset from the inside.
PG5
HOME SECURITY DOCUMENTATION
Shane Millham and Justin Sangiorgi
ALARM TRIGGER
If the incorrect code is inputted 3 times or the timer counts to 14 the alarm is enabled. If the
correct code is not inputted for no code is inputted and one of the doors or windows is opened
then the alarm is enabled. If a window is open when the alarm is reset the window will be
ignored, therefore the alarm will not be triggered by the window being opened. This occurs
because of the D latch on the upstairs windows, which holds a one if the windows are open
when the reset or leaving button is pressed. If the door is left open when the alarm resets the
alarm will automatically trigger. At this point the alarm can only be turned off from the inside.
TRIGGER SYMBOL
PG6
HOME SECURITY DOCUMENTATION
Shane Millham and Justin Sangiorgi
LEAVING HOUSE RESET
When the leaving button is released a 5 second timer consisting of 3 “D” flip flops is initiated.
During this 5 seconds the homeowner is able to leave the house without the alarm triggering.
After the 5 seconds the D flip flop is reset and the alarm is reinitialized. If the door is still open
or is opened after the 5 seconds the alarm will sound. This situation is anded with the normal
hard reset, so whenever you just reset the system or are leaving the house, the and goes low and
resets the entire system.
HOLD RESET SYMBOL
PG7
HOME SECURITY DOCUMENTATION
Shane Millham and Justin Sangiorgi
AUTOMATIC GARAGE DOOR
The garage door is triggered when the correct code is inputted and the garage sensor is
triggered. Once triggered the clock starts an 8 bit counter. For the first four seconds the garage
door will be opening and the last four seconds it will be closing. The car will have about 8
seconds to get into the garage before it will be completely closed. This will only occur if the
correct code is inputted while a car is triggering the garage door sensor. If the code is not
inputted correctly or a car isn’t triggering the sensor than the garage will remain close.
GARAGE SYMBOL
PG8