Alternative Buzzer signal generation for Piezo speakers?

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LenzGr
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Alternative Buzzer signal generation for Piezo speakers?

Post by LenzGr »

As far as I understand it, the current buzzer code simply changes the buzzer pin from low to high and it's up to the buzzer hardware to actually convert this into an audible signal. Wouldn't it also be possible to have the flight controller generate a PWM signal on that pin that could be used to drive a small piezo speaker? It probably requires a dedicated amplifier circuit (a transistor or something like TI's LM4960 driver chip), but it would have some benefits:

  • No magnetic interference
  • Much lower power consumption than traditional beepers
  • Multiple beep frequencies possible
Thoughts? Considering the relatively low frequency, I think the PWM generation could be done in software without adding too much additional cycles (there actually is a Tone() function in Arduino, but that would probably interfere with our other PWM generating routines)

References:

http://hades.mech.northwestern.edu/inde ... with_a_PIC
http://tronixstuff.wordpress.com/2010/0 ... -thirteen/
http://www.picbasic.co.uk/forum/showthread.php?t=3076
http://www.electronicspoint.com/driving ... 39264.html

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jevermeister
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Re: Alternative Buzzer signal generation for Piezo speakers?

Post by jevermeister »

Interesting idea.

I will have a look at that.

Nils

PonyoFS
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Re: Alternative Buzzer signal generation for Piezo speakers?

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LenzGr
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Re: Alternative Buzzer signal generation for Piezo speakers?

Post by LenzGr »

PonyoFS wrote:You can use this :
https://www.sparkfun.com/products/7950

Actually, this is not a Piezo speaker, it's a regular buzzer with a magnet. What I am envisioning is either driving a pure piezo with a PWM signal on the buzzer pin, or creating a small PCB that contains a piezo speaker and some circuitry to generate the waveform signal, so it can simply be connected and enabled with the current high/low signal on the buzzer pin.

PatrikE
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Re: Alternative Buzzer signal generation for Piezo speakers?

Post by PatrikE »


LenzGr
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Re: Alternative Buzzer signal generation for Piezo speakers?

Post by LenzGr »

PatrikE wrote:Or with a 555 timer.
http://www.kpsec.freeuk.com/555timer.htm#astable


Yes, I was thinking about that, too! A small PCB with a piezo and an NE555 plus the analog pieces should make a nice little breakout board. No magnetic field and the power consumption should be fairly low. I wonder if this circuit could be powered off the LEDPIN directly or if we would need to connect it to Vcc as well...

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dialfonzo
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Re: Alternative Buzzer signal generation for Piezo speakers?

Post by dialfonzo »

Hi All,

I've been looking for similar functions myself.
Anybody been able to implement a simple Piezo Buzzer ?

:)

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