Impact sensor/quick 3v signal. Ideas to use?

I can figure out the specifics but some guidance whether I am heading in the right direction would be helpfull.

The project: Making an RGB(A) high power lighsaber driver than can interface with existing lighsaber sound card. (Driving 10W LedEngin RGB(Amber) LED.)

The soundcard I am using has an "Impact" or "Shock" sensor that verrry briefly goes high to 3.0V when it abruptly changes acceleration. (Essentially a spring that flexes and hits the side of a can completing the circuit.)

Because the signal is so short, do I need to use an interrupt to "catch" it? Also, will 3V trigger a change in state or do I need to up the voltage?

If I do need to up the voltage.. my first thought was an OP amp, but really an active circuit would be a real PITA... (Limited space)

What about hooking the sensor to a 5V signal, then using a resistor to drop the signal to 3V for the soundcard but taking the signal before the resistor for the Arduino? (I will be using a Nano, by the way but I'm prototyping on a Duemilanove.) It's a simple mechanical device, so the 5V shouldn't hurt it, I don't think.

Anyway... advice/suggestion/questions are apprciated!

Thanks in advance!

Anything at or above 0.6 * VRef (typically 5V) is considered HIGH, so 3V will be considered HIGH.

Your definition of short, and the Arduino's, are likely quite different. At 16MHz, the digitalRead in the loop method should catch the signal quite reliably.

Awesome... that's great news for this particular implimentation... no "extra bits" in an already crowded space.

I would indeed rather hang on to that intterupt pin if possible. It's not really needed now for anything else at the moment, but in the future we want to add an accelerometer and sound playback to it. (That way no secondary sound card will be needed.)

I'll try just the straight 3V and checking "In the loop" for it. I've already been thinking ahead (well trying to) and doing things like not using delays that hold up the code execution so it should still be running a loop pretty "fast" and so it will be checking pretty often.

The voltage difference ended up being a moot issue... ends up the board is designed for 4.5V, so 5V was within range to run the board from. (It was so long since I scavenged it I forgot it had three batteries... 'Doh!)

PaulS, you were exactly correct that just "checking in the loop" worked just fine for catching the signal... hasn't missed one yet.

Thanks for the help!