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Author Topic: (Probably) Simplest Arduino based Sound/Lightning Trigger  (Read 2136 times)
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I have just finished a small project -- sound trigger. It is very stable yet very sensitive -- it can detect a moderate finger  snap 3-4 ft away.

Schematics and construction:


Code:
Code:
//  
//    This is a sound trigger for Arduino using simple Piezo
//    as sound sensor, it is quick and dirty, but highly sensitive
//    device that can detect a moderate finger snap in 3 ft
//
//    Copyright (c) 2013 Peter Y Lin (a.k.a MJKZZ)
//
//    Permission is hereby granted, free of charge, to any person
//    obtaining a copy of this software and associated documentation
//    files (the "Software"), to deal in the Software without
//    restriction, including without limitation the rights to use,
//    copy, modify, merge, publish, distribute, sublicense, and/or sell
//    copies of the Software, and to permit persons to whom the
//    Software is furnished to do so, subject to the following
//    conditions:
//
//    This permission notice shall be included in all copies or
//    substantial portions of the Software.
//
//    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
//    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
//    OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
//    NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
//    HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
//    WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
//    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
//    OTHER DEALINGS IN THE SOFTWARE.
//
#include <avr/io.h>
#include <avr/interrupt.h>

#define    FLASH_PIN      7
#define    SOUND_PIN      A0

#define    TIMEOUT        100  // 100 milliseconds
#define    THRESHHOLD     2  

void setup()
{
  Serial.begin(115200);
  
  // make flash trigger pin output
  pinMode(FLASH_PIN, OUTPUT);
  // keep flash trigger pin low
  digitalWrite(FLASH_PIN, LOW);
}

volatile int v1 = 0;
volatile int v2 = 0;
volatile int to = 0;

void loop()
{
  // start analog read
  v1 = analogRead(SOUND_PIN);
  while(1)
  {
    // acquire again
    v2 = analogRead(SOUND_PIN);
    
    // if difference between two analog read exceeds threshhold,
    // and it has been timed out since last trigger,
    // then trigger flash
    if (abs(v1 - v2) > THRESHHOLD && to == 0)
    {
      // debug only, you can remove it
      Serial.println(abs(v1 - v2), DEC);
      
      // *** edit your code to insert time delay here ***
      
      // trigger flash
      digitalWrite(FLASH_PIN, HIGH);
      // keep flash trigger high for 1ms
      delay(1);  
      // done triggering, reset back  
      digitalWrite(FLASH_PIN, LOW);

      // set timeout value to prevent multiple triggering
      // unit is number of milliseconds
      to = TIMEOUT;
    }
    v1 = v2;
    
    // decrease timeout value
    if (to)
    {
      to--;
      delay(1);
    }
  }
}
« Last Edit: February 13, 2013, 04:42:58 am by mjkzz » Logged

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Very cool! What sort of microphone/speaker was that? I was trying to detect the tick of a grandfather clock with only partial success.

You could use the analog comparator instead of analogRead, that might give slightly faster response (not that it probably matters):

http://www.gammon.com.au/forum/?id=11916
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Very cool! What sort of microphone/speaker was that? I was trying to detect the tick of a grandfather clock with only partial success.

You could use the analog comparator instead of analogRead, that might give slightly faster response (not that it probably matters):

http://www.gammon.com.au/forum/?id=11916

Oh, it is a piezo type of buzzer which can also be used as sound (pressure) sensor -- it generates voltage under pressure or sound.
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Very cool! What sort of microphone/speaker was that? I was trying to detect the tick of a grandfather clock with only partial success.

You could use the analog comparator instead of analogRead, that might give slightly faster response (not that it probably matters):

http://www.gammon.com.au/forum/?id=11916

Very cool project you have there, too. I am new to Arduino world, but I'd love to use the comparator mode for this. Or even do a lightning/thunder trigger. Thanks for the tip.
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Actually, I put in a photo diode in with positive terminal going into A0 and negative terminal going into Gnd on the Arduino, it can detect a Yongnuo 560 at 1/128 power level 15 ft away -- not pointing at the flash, but pointing at the ceiling. I am sure if pointing to the light, it can detect it at even further distance.

The photodiode is BPW21R

So, it should be good to detect lightning.
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That is the most elegant solution to this type of triggering I have ever seen. Well done. I am totally copying it for future reference.
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I am having a problem with this circuit. I can detect noise and see the serial monitor respond, however the flash will only fire when I remove a wire and from the circuit. Does this possibly have with the fact that I am using a disposable camera flash unit. Any help is appreciated.
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C program run. C program crash. C programmer quit.

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