Alarm

[Kiran Chinnam]

I am considering a Smart Alarm project using IOIO. Most of the ports on an alarm panel are just digital IO. However, is the internal sounder. What is the best way of producing a loud sound via a speaker using IOIO. 

So far, i am thinking I could use a 556 timer to produce a siren tone. Any there any other, more cost effective ways of doing this as there needs to be an android device there to drive the IOIO board. Aswell as that, the Android can double up as web server for remote operation, a speech dialler and texter via GSM/CDMA. The Android is also going to be a 'Smart  Keypad'. I know I can use an amplifier and use the android to produce the sound, but the IOIO in the main box has to be able to produce sound inthe case of android device removal i.e. Tamper alarm.

P.S. if an android if disconnected from IOIO, will all digital IO switch off or freeze?

If I have a 12v 5A psu, I use 1A and then connect 5v multiple switching regulators to the 12V supply, Can I use 8 Amps+ 

[Ytai Ben-Tsvi]

On Fri, May 24, 2013 at 8:56 AM, Kiran Chinnam <kchin...@gmail.com> wrote:

I am considering a Smart Alarm project using IOIO. Most of the ports on an alarm panel are just digital IO. However, is the internal sounder. What is the best way of producing a loud sound via a speaker using IOIO. 

The simplest way is to buy a buzzer and just switch its power on / off through a transistor.

 

So far, i am thinking I could use a 556 timer to produce a siren tone. Any there any other, more cost effective ways of doing this as there needs to be an android device there to drive the IOIO board.

If you don't want a buzzer, you can use a PWM pin to generate an audio-frequency signal and connect to a speaker though a simple amplifier (as simple as a transistor circuit).

 

Aswell as that, the Android can double up as web server for remote operation, a speech dialler and texter via GSM/CDMA. The Android is also going to be a 'Smart  Keypad'. I know I can use an amplifier and use the android to produce the sound, but the IOIO in the main box has to be able to produce sound inthe case of android device removal i.e. Tamper alarm.

P.S. if an android if disconnected from IOIO, will all digital IO switch off or freeze?

They all go floating. You can use a pull-up/down resistor to determine the default state, and in your case, you can have this default state "buzzing".

 

If I have a 12v 5A psu, I use 1A and then connect 5v multiple switching regulators to the 12V supply, Can I use 8 Amps+ 

If I understand you correctly:

8A x 5V = 40W. Ideally, this translates to about 3.5A x 12V, so you should be OK.

 

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[Kiran Chinnam]

Thanks for the reply.