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Computer Activated Alarm Answered


I am trying to make a simple alarm system for ill patients, the alarm will be activated through a mouse click on an alarm icon and trigger an alarm connected to the PC.

Does anyone have any ideas on how to tackle this problem?

Many thanks in advance :)


I would probably do it in Processing, which would operate an alarm via serial connection. If you don't know Processing, I could quickly write up an example program, but I would have to do it tomorrow. As for the alarm itself, you could do it with arduino, but that would be expensive and rather impractical. You could do it with something like the PICAXE 28x1, that would at least be cheaper than an arduino.

I figured out that the parallel port idea is pretty useless as virtually no new laptops contain these or even serial ports.

Is there anyway that the alarm could be powered and controlled through usb, I've also picked up a usb to serial converter cable if that is useful in any way?

Ah ha! Ignore my last comment. I found what I was looking for. I'm pretty sure this is perfect....

USB Sensors with an AtTiny

He uses the AtTiny and an LDR to sense light on his laptop. The usb stack is handled by the AtTiny and the AtTiny takes input from the LDR. Would be trivial to swap the LDR for a button. These uCs cost about $2 each. You would however need to buy a PCB from him if he has any left, or throw together a design of your own.

Hey mate, thanks for the idea I'll follow it up and have a try making my own design.

A friend also told me about using a micro maestro http://www.pololu.com/catalog/product/1351 which is used to control small servo motors for robotics projects. I managed to grab one off him so I'm going to have a play around with that aswell

wrote a quick program in C# for the micro maestro and it was able to turn the alarm on and off via an emergency button display. I then installed power menu which has a feature for a set program to always stay on top so the program is always visible to the user, so they can always trigger the alarm

You might do well with one of the cheap USB controlled atmel uC boards. You need enough grunt to handle the USB stack plus one input.

The Teensy is pretty cheap at $16. An atmega32 seems overkill for what you're using though.

I found several sites talking about USB firmware for all Atmel AVR uCs. This means you could run it on some of the smaller ones, the AtTinys without needing additional ICs like those by FTDI (I think, from quick reading.)
AVR Virtual USB: http://www.obdev.at/products/vusb/index.html
USBTiny: http://dicks.home.xs4all.nl/avr/usbtiny/

If you want to pursue this you might do better to head over the the AVRFreaks forum and ask again. They might know of a cheaper product than the Teensy that you can use as a usb controller and 1 input.

(PS, please stop clicking the Feature Comment button, it stops people from replying to your posts)


5 years ago

Hi guys thanks for the comments, really appreciate them.

Firstly, big red emergency buttons are commonly used in hospitals and are very helpful, but in this case, I forgot to mention that the patients have very high level spinal cord injuries and are unable to activate a switch by hand/foot.

But the parallel port idea got me thinking and i stumbled upon this eventually: http://members.iinet.net.au/~alw1746/awhome/electronics/AlarmParPort/index.htm

The idea of using a serial connection and a PICAXE is a great one and one I will try. When you say do it in processing, would writing the code in C# work fine ?

Thanks again!

If they are truly ill, trying to match up a mouse pointer with an icon might or could be a bit much. There a ton of ways to hook a simple switch to the parallel port and monitor input The switch that could be in form of a big red emergency button.