Electronic – Piezo buzzer giving faint clicks instead of loud buzz

gpiopiezo-buzzerraspberry pi

Please note: Even though this question involves a Raspberry Pi, I really think its an essential electronics question at its heart, and that the fact that I'm dealing with a Pi is secondary.

I have the following piezo buzzer wired up to my Raspberry Pi 1 Model A (hereafter RPi) as follows:

When my software (which uses wiringPi under the hood) sends an output signal to GPIO output pin, which is the pin driving the buzzer, it just makes a faint clicking noise, not a big booming buzzzzzz like I expected. I'm trying to figure out why.

My thoughts:

Perhaps its not as simple as just sending a HIGH signal to the buzzer…perhaps there's a more sophisticated signal I need to send it
Perhaps the buzzer is junk, however I ordered 3 of them from DigiKey and all three produce the same faint clicking sound
Perhaps something else isn't wired correctly

I have confirmed that my software is sending an output signal to the correct GPIO pin, namely because the buzzer does click when the software sets this pin HIGH.

Any idea how I can troubleshoot here and begin diagnosing?

Best Answer

As I suspected the buzzer you linked to does not have a built-in oscillator. It must be externally driven with a square wave per the datasheet. You can do this by switching the GPIO pin on and off repeatedly at the frequency you want your buzzer to "buzz" at.

Related Solutions

Electronic – Driving a single-relay board with Raspberry Pi

Looking at the photographs of the relay board, it looks to me like the transistor is acting as a high-side switch for both the relay and the LED, since one of the transistor leads goes directly to "+" and one of the relay coil pins goes directly to "-" (the ground plane). Therefore, the transistor would either be a PNP BJT or a P-channel FET. I'm betting on the PNP.

This would mean that you need to ground the "S" pin to activate the relay, and you need to open-circuit the pin, allowing it to float all the way to 5V, to deactivate it. Simply driving it to 3.3V will still keep the transistor activated. Although, I admit, this doesn't explain the changes in the LED, unless the voltage across the relay coil is changing enough to cause the LED to dim without allowing the relay to drop out.

In other words, the relay board is designed to behave much the way a bare relay coil would work (with low-side switching), but without requiring whatever's driving it to sink the full current of the relay. This makes a certain amount of sense.

Electronic – Cannot get a digital square wave on oscilloscope from the GPIO of the Raspberry Pi

There are a couple of issues with your code that can be easily fixed. First, you are calling wiringPiSetup which means you will need to refer to the pins by their WiringPi designation which can be found on this page:

https://projects.drogon.net/raspberry-pi/wiringpi/pins/

You are then setting pin 7 (wiringPi designation) to be an output which is actually GPIO 4 (physical pin 7) and not the CE1 pin as you mentioned. CE1 would actually be wiringPi pin 11.

The next problem is in the while loop. You are doing a digitalWrite on wiringPi pin 4 (not 7 as you configured) and are always setting it low so it would never toggle high even if configured correctly. The following code should be what you are looking for but is not tested. This assumes you want to use CE1 which is normally used for SPI but should work with WiringPi as an general I/O pin:

  if (wiringPiSetup () == -1)
    exit (1) ;

  pinMode(11, OUTPUT);

  while(1) {
    digitalWrite(11, 0);
    digitalWrite(11, 1);
  }

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