NOTIFY ME NOW!
One young maker’s home security system. BY GOLI MOHAMMADI
At Maker Faire New York
2011, 13-year-old Andrew
Katz displayed an automated
dollhouse that showcased
his Arduino-based Notify
Me Now security system. He
drummed up quite a bit of
interest and inspired us all.
it a device that has plugs for sensors,
plugs for outputs, and a program that
is completely customizable to the user.
I want it to be open and free, with the
ability to be used for anything.
a picture on the screen. I did some
troubleshooting, and lastly, did final
tests to make sure everything worked
like I wanted it to.
What motivated you to create
an automated dollhouse?
I decided to install the system in a
dollhouse because it would be easier
to tinker with, but my main plan is to
install the system in a real house. The
day I came up with the idea, the dog
had gotten into the garage without us
knowing, and my brother snuck into my
room and scared the living daylights out
of me. I thought, “Well, I like Arduino,
I am experimenting with ultrasonic
sensors, I like my laptop, and I hate it
when people sneak around. Sounds like
a good project!” So I decided to create
an Arduino-based secret notification
system to alert me by changing a pic-
ture on my laptop’s screen if someone
tripped a sensor. That way, only I knew
where someone was in the house.
How did you get interested in
When I went to the Maker Faire New
York for the first time in 2010, I got introduced to the Arduino. I liked it a lot, but
I knew I would have to learn to program
it to use it properly, so I decided to take
an introductory programming course
on my new iPhone. Mom thought that
I should take Stanford’s Programming
Methodology course. I really enjoyed it,
and I learned a lot about Java and good
programming practices. After, I also
read a book on Arduino, and since then
I have fallen in love with programming.
How does it work?
The project has ultrasonic capabilities
and pushbutton abilities built in natively.
It also supports many other sensor
types, from sound to light to pressure
pads to websites. On the Arduino’s
startup, it takes a baseline reading of
the sensors, then it checks the current
sensor reading against the baseline. If
there is a difference, it sets off an alarm
and sends a message to the computer,
telling it to change a picture on the
screen. The alarm is optional, and the
pictures are user-customizable.
What was your R&D process?
Is Notify Me Now a prototype?
Yes, but the final system will be an
improved design, with support for other
sensors that an Arduino can support.
I think that the basic concept is there,
but it can do much more. I want to make
I had a book that talked a little bit about
Processing and about the ultrasonic
Ping sensors, so I started there. I also
went through the online documentation about the sensors. Then I wrote
a simple sketch, which would signal
when a sensor was tripped, and began
testing. From that point until when the
Processing code was written, it was trial
and error. By the end, I had created a
range of values that would be accepted
to trip the alarm instead of just one.
This allowed for fewer false alarms. I
then wrote the Processing code to get
the signal, to forward it to an Arduino
with a buzzer attached, and to change
What advice do you have for other
Always go for your ideas, repurpose
things, and never give up. Always try
an idea that you come up with, no
matter how stupid it seems. It can be
frustrating at times, but you need to
always keep going. You can take a break,
though. There is a lot of useful informa-
tion out there, online and in books, so
whenever you get stuck, just look for the
answer or keep experimenting until you
figure it out. Be persistent, only ending
a project when it’s done. ;
Download code files for Notify Me
Now at makezine.com/go/notify.
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