simple one tone generator at ramdom time

Forum 2005-2010 (read only) Hardware Interfacing
1

hi!

i'm trying to build a simple one tone generator based on this code:

/*

  • Blink_Randomly
  • Modified from the basic Arduino example. Turns an LED on for a random time,
  • then off for a (most likely) different random time. We use pin 13 because,
  • depending on your Arduino board, it has either a built-in LED
  • or a built-in resistor so that you need only an LED.
  • Original at - http://www.arduino.cc/en/Tutorial/Blink
    */

int ledPin = 13; // LED connected to digital pin 13
long randOn = 0; // Initialize a variable for the ON time
long randOff = 0; // Initialize a variable for the OFF time

void setup() // run once, when the sketch starts
{
randomSeed (analogRead (0)); // randomize
pinMode(ledPin, OUTPUT); // sets the digital pin as output
}

void loop() // run over and over again
{
randOn = random (100, 1200); // generate ON time between 0.1 and 1.2 seconds
randOff = random (200, 900); // generate OFF time between 0.2 and 0.9 seconds
digitalWrite(ledPin, HIGH); // sets the LED on
delay(randOn); // waits for a random time while ON
digitalWrite(ledPin, LOW); // sets the LED off
delay(randOff); // waits for a random time while OFF
}

i thought that if i conected a speaker right to the pin output i would get a tone, but aparently not. I only get a very low click...

the idea is to repeat the same tone at random times.

any ideas?

thank you in advance :slight_smile:

2

One idea would be to use "delayMicroseconds" instead of "delay".
But that'll just give a slightly shorter click unless you loop it.

Another idea would be to use the tone library.

Yet another would be to click on "modify", highlight the code in your post, then click on the # button in the editor toolbar.

3

i allready have the tone library on my computer, but i don't understand how to use it... :-/

any simple way to associate the pin output to a tone?

4

http://code.google.com/p/rogue-code/wiki/ToneLibraryDocumentation

5

Not sure why I persist in trying to get this across, I guess the I thought the technique was worth sharing.

So if . . .

  • you want to actually drive a speaker & can connect it properly
  • you don't want to use the tone lib

than this change to your code should give you the loudest sound since it's like using 10V peak to peak . . .

int speakPinA = 13;               // ONE SIDE OF SPEAKER (using int is silly BTW)
int speakPinB = 12;               // OTHER SIDE OF SPEAKER

long randOn = 0;                  // Initialize a variable for the ON time
long randOff = 0;                 // Initialize a variable for the OFF time


void setup()                      // run once, when the sketch starts
{
randomSeed (analogRead (0));    // randomize
pinMode(speakPinA, OUTPUT);        // sets the digital pin as output
pinMode(speakPinB, OUTPUT);        // sets the digital pin as output
}

void loop()                       // run over and over again
{
randOn = random (100, 1200);    // generate ON time between 0.1 and 1.2 seconds
randOff = random (200, 900);    // generate OFF time between 0.2 and 0.9 seconds
  digitalWrite(speakPinA, HIGH);   // pushes speaker/piezo cone out
  digitalWrite(speakPinB, LOW);
  delay(randOn);                // waits for a random time while ON
  digitalWrite(speakPinA, LOW);    // pulls speaker/piezo cone in
  digitalWrite(speakPinB, HIGH);
  delay(randOff);               // waits for a random time while OFF
}

Otherwise take the trouble to understand the tone lib.

BTW if you are making something like a simulated Geiger counter sound and just want random "clicks" you may be better off with a piezo.
Find one of the resonant freqs. of the piezo, and create short bursts (~5mS). It will sound like a click.
[edit]Tried this at home and noticed I forget to add pinMode(speakPinB, OUTPUT);. Corrected the example above. Technique makes a significant difference in the volume of a piezo. [/edit]

6

aah!
earlyer i didn't understad that i had to conect the speaker ground to a diferente pin!

works great! thanks a lot!