Using a smoke detector to move motors

I’m trying to use a smoke detector to activate and turn 2 stepper motors. How would I go about setting something like this up? (See below for details)

I have a traditional 9V powered ceiling (2 of them actually) smoke detector that I would to connect to an Arduino Mini Pro (3.3V, ATMega 328, 8Mhz). I want to know how to connect this to the arduino (Mainly as a digital but analog is fine as well). I want to be able to detect when the alarm is going off (I don’t really need to know when it turns off because I’d reset the arduino by hand). I was considering hooking the arduino up to the speaker of the alarm (because the speaker outputs 3.3v) to send a digital value over to the arduino.

My questions are: How to set this up (schematic wise, or wiring wise :P)? How I would program it. (Like setting a pin to INPUT and then reading the value every so often) and anything else you can think of to help me would be awesome. Also, if something is a bit confusing, just ask and I’ll elaborate.

I want to be able to detect when the alarm is going off

You can add a microphone to the Arduino and just detect its sound, problem is environment noise. You can also locate the buzzer on the smoke detector and connect an Arduino IO pin with this. Depending on the voltage you need digital IO or analog IO.

The sample frequency depends on how fast you want to react on the smoke ...

Hello !

Maybe you can use an external falling edge interrupt on INT0 pin, maybe it could solve the reading frequency ;) But you have to know the smoke detector schematics, especially on the speaker output in order to know how interface it with the INT pin. The best is to "google" your smoke detector and see if you find any usefull information ;)

Edit: A link about external interrupts http://arduino.cc/playground/Code/Interrupts

However i don't really understand the purpose of your project, you want to drive stepper motors when the alarm goes off ?

However i don't really understand the purpose of your project, you want to drive stepper motors when the alarm goes off ?

Probaly to handle the fire extinguisher automagically ;)

More serious applications, smoke shows in a magician act , discotheque , open a chimney above a fireplace (cheminée (?)), etc.

suggest you stick to one thread not two asking the same question multiple times in different threads is a bad plan

robtillaart:

open a chimney above a fireplace (cheminée (?)), etc.

You speak french a little ;) ?

Ok i see what kind of application you can do with this , but i have understanding problem with this sentence ;) :

I want to be able to detect when the alarm is going off (I don't really need to know when it turns off because I'd reset the arduino by hand)

mmcp42: suggest you stick to one thread not two asking the same question multiple times in different threads is a bad plan

Yes it is a bad plan as you say ;)

You speak french a little smiley-wink ?

Oui, je parle un peu de francais - quatre ans a lécole -, mais il est longtemps je parle a vacances ;)

If the detector has a piezo element for alarm sound, you can jack-in mid-wire to the signal driving the element. When the alarm activates, the tap will receive a square wave probably ... use that to trigger an Arduino input.

Just an idea here, might not work. Get a needle to push through plastic wire and test which wire sends an electric current when the buzzer or alarm goes off, and program Arduino to move motors when a current is detected.

I have seen a very nice hack on an ionization smoke detector where the analog output from the chip on the smoke detector can be connected to the analog input on your arduino, giving you the oppertunity to fine tune the level at which you want to control your motors http://www.flickriver.com/photos/geekphysical/6618727785/