Security System Design

Security System Design-Final Report
Nick Battista, khalfan Almehairbi- Team QTpi
Lab 3
Dr. Timothy Wheeler
EE 300W
A security system contains electrical hardware and software that work together to restrict
access to users for safety. These systems can be implemented in many ways and one is through
the use of microcontrollers. Microcontrollers are capable of creating lower level subsystems
that work together to create one large security system. Computer security is an important
feature in today’s society and must be created with caution.
This design requires the use of many subsystems that are implemented using microcontrollers
to create one large security system. These microcontrollers can utilize several security devices
that are interconnected such that one subsystem must give access for the next one to perform.
The subsystems can be developed by different teams with the final goal to implement them all
together. The subsystem our team has been developing utilizes a camera, the LinkSprite SEN10061, to capture an image of the user to save to a host computer to grant access to the rest of
the system.
A successful security system that is proposed contains six subsystems communicating together
to grant access. Creating this security system requires precise and accurate subsystems and one
of these is the camera image access. The camera must communicate through hardware, a
microcontroller in this case, and software. The software must initiate the camera to take an
image. A good camera subsystem also saves and displays the image of the user before granting
access to the next subsystem.
To grant access to another subsystem, the microcontroller must send out a signal to allow for
the next subsystem to run. This can be done using CAN bus which connects subsystems through
node priority. A prior node must grant access for a subsequent node and its subsystem to
begin. The Linksprite camera and mbed NXP LPC 1768 microcontroller have the capabilities to
create the necessary security system.
Figure 1: LinkSprite SEN-10061 Camera
Figure 2: mbed NXP LPC 1768
The camera must be one of several subsystems that communicates together to create a
security system. The design was broken down to have each team work on one subsystem
specifically so each of the individual subsystem requirements could be met. Our group
developed the camera subsystem. The camera communicates with the mbed through C code.
This code is run through the mbed online compiler and downloads to the microcontroller
through the use of USB. The code meets the requirement by initiating the camera to take a
picture of the user.
The C code was designed based off of the example code given on the mbed website. We were
able to alter the code to run as an infinite loop so multiple pictures could be taken if the user
tries to gain access again. The Putty terminal interface was used for or verification testing .
Once the testing performed correctly the C code was than altered to communicate through
Remote Procedure Calls (RPC’s) to communicate through labVIEW.
The labVIEW software code meets the level 2 requirements of recording an image and saving it
as a jpeg. On the labVIEW front window the user is able to click a button to make the camera
take a picture. LabVIEW then saves the image to the host computer and displays the image of
the user. The requirements could be verified since it easily can be seen that a picture is
displayed on the front panel window. The picture could also be found saved to a specific folder
on the computer. Meeting these requirements required the labVIEW to be altered several
times to fix a timing issue that occurred with the camera. This was verified through Putty and
once diagnosed the labVIEW was altered to have a while loop wait 15 seconds when taking a
picture. This allowed enough time for a picture to be fully taken and would only wait .1 seconds
when not taking a picture.
Figure 3: LabVIEW Block Diagram
Figure 4: LabVIEW Front Panel Diagram
After the requirements were met, the camera could be used as an integral part of the main goal
of creating a security system. Once the camera takes an image of user, saves it, and displays
the image than the system could grant access for the next subsystem to perform its functions. If
an image was not taken or saved correctly the camera subsystem would not allow access and
the next system could not work.
This communication of access granted or denied was done using CAN bus protocol. CAN was
chosen due to its ability to communicate through node priority. This priority means that one
node cannot work unless the prior node is working correctly. In our system a node would be
represented by each subsystem. The CAN priority was set in the C code that would pass a value
of “1” to the next subsystem if access was granted. Each subsystem was connected through a
CAN transceiver hooked up to the microcontroller.
Figure 5: CAN Transceiver Layout
The final integration between subsystems did not work properly as hoped. There was an issue
where the host subsystem was not able to read any value other than “0” from any of the
subsystems. We could not fix this issue before our deadline was done but, we believe there was
an issue in the host subsystems code that gave priority to their system that would not allow
other systems to communicate.
Table 1: Financial Chart
Mbed LPC1768
LinkSprite SEN-10061
2 Microchip MCO2551
Total= $122.34
Value Statement:
The camera developed by our team was capable of taking a picture, saving it, and granting
access. This makes the subsystem a valuable asset for creating the larger objective of an
integrated security system. The use of the mbed microcontroller made the development simple
and cheap to implement. The system is highly customizable due to the capabilities of the
The security system subsystems were all capable of performing their individual duties. The
camera subsystem designed by our team meet all of the requirements necessary to work
exactly as hoped. The main issue that could not be solved was communicating between each
subsystem. If there was more time the communication issues could have been solved and our
camera would be a perfect fit to integrate into the main security system goals.