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[on:]

Hi all!

I made a simple alarm with an arduino uno. The arduino has a digital port set as input, which tells it if it is armed or disarmed.
Another is connected with an ir movement sensor, and another is an output connected to a relay, with a siren mounted on.

My question is, for how long will an arduino work without problems? Is it bulletproof? Will it stay there forever waiting someone to brake in? Will it respond every time i arm it? Or after a while it will fail due to memory problems for example? In general, can i trust it for an alarm system, or a home automation one with no reboot?

[Reply #1 on:]

I would not say a normal Arduino running non-professional code off a wall wart is "bullet proof", but in general, with a well-written program, reliable power supply etc you would expect it to run indefinitely.

______
Rob
 

[Reply #2 on:]

And can you tell me where to read some professional-written code to compare?

[Reply #3 on:]

You are right!

It is easy to implement it with a couple of relays, a flip flop and some more. But the alarm/sensor is a part of a larger project of total home automation. The final project should control everything. From the doors to the water supply. Thats why it needs to be bulletproof or to fail gracefully as you say. It has a web page to control it with anything on a network. But the point is to be automated. To see and interact. To pass as clever. And to some point is done, but recent problems had made me asking about credibility. Can i rely on arduino to deliver? When im done i will post the code to evaluate if its ok with you. It is not commercial, it is for my home, which i built to accept a controller to handle everything. My project is powered through a large ups, so power is not a problem. Portability is not an issue also, and connections aren't a problem since i had short circuit problems. I ve made a custom board. The weak link is the code or/and the arduino, if it can be a weak link.
Here, in Greece, we do not have home insurance. We do not even think about it. So it is not a problem.

[Reply #4 on:]

The hardware will generally do fine.  There are a few things that will help in your quest for bulletproofing

• Diagnostics, monitoring, notifications. You'll want easy ways to determine whether things are working, and a way to find out when they're not
• Testing.  Exhaustive testing if every component will help flush out the bugs
• Avoid libraries.  The least stable parts of an Arduino system are the libraries.  Especially stuff off the playground, but even the packed in  have occasional issues.  The less code you have, the less bugs.

[Reply #5 on:]

I saw a master caper movie once. The bad guys just sprayed a quick setting foam into the alarm horns before breaking the security circuits.

Lefty

[Reply #6 on:]

Hi,

I just came across this post. So I've been running a IR based home automation system and its uptime is 321 days, it hasn't crashed since, no random number generation nothing. A machine is as good as its code. I hope that answers your question on the bullet-proof-ness of arduino. Its pretty reliable, after all its just a bunch of counters registers and adders (it will remain intact till you mess up the supply or any other external factor on which its dependent).

[Reply #7 on:]

and thousands (10s of thousands?) of transistors simply has more to go wrong.

Considering a DS3231 RTC has 33000 transistors I'd say hundreds of thousands.

[Reply #8 on:]

Thank you all for your answers. I will post my project as soon as it is finished.

I saw a master caper movie once. The bad guys just sprayed a quick setting foam into the alarm horns before breaking the security circuits.

Lefty

The foam that you are looking for is polyurethane, it is very good for that job, but there are foam-resistant sirens nowdays... just google it.

[Reply #9 on:]

but there are foam-resistant sirens nowdays

I bet people didn't think that would be something they would need to make

[Reply #10 on:]

A few years ago I built an arduino-based controller for a dust collector (woodworking equipment).  It's been running 24x7 ever since, hasn't failed to work once.

just a data point.

-j

[Reply #11 on:]

Like said previously, stay away from the libraries! If you want something done right, you better do it yourself.

[Reply #12 on:]

Lots of things are more likely to let you down in such a system before the Arduino messes up... for instance, how can you be sure that there will be power? Bad Guys are not unknown to take advantage of power outages to "visit" properties.

I have one that runs my Perpetual Pendulum....

sheepdogguides.com/arduino/aht8pendu.htm

... for weeks at a time without needing a reset. (I'd claim longer up times for it, but I turn it off from time to time, and the dog knocks the electromagnet out of place from time to time.)