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#Safe current for arduino piezo zip file
#Safe current for arduino piezo code

The pitches library is not found in the Arduino IDE but you can download the ZIP file from Github and include the library in the Arduino IDE by clicking in the menu line: Sketch -> Include Library -> Add.

#Safe current for arduino piezo code

If you take a look into the source code of the library you see that the library is nothing else than a lookup table for different notes to their frequency. You could now use the tone function and define the connected output pin, the frequency and the duration of the output generation, but if you do not know the frequency of different notes, we can also use the pitches library from Mike Putnam. Instead we use the Arduino tone function to generate a square wave of the specified frequency (and 50% duty cycle).

Therefore we can not use the analog write function, because this function has a fixed frequency of 500Hz. To create a melody the passive buzzer needs an AC signal where we can define the frequency. Let me know in the comment section if you know the melody that we create in this example. The passive buzzer has the advantage that we can not only create a tone, but also a melody with different frequencies. The digital I/O pin of the Arduino, EPS8266 or ESP32 microcontroller is therefore connected to the gate of the MOSFET with a resistor of 220Ω in series, because the Arduino operation voltage of 5V or even the 3.3V operation voltage of the ESP8266 or ESP32 would damage the transistor. Otherwise we were not able to switch off a load that has a higher voltage than the control voltage.

Low-side switch: The transistor is on the low (ground) side of the circuit and the buzzer is connected on the high (5V or 3.3V) side.

You can see the diagram they provide below.

NPN transistor: Because we want to turn the active or passive buzzer on by setting the digital pin of the microcontroller HIGH. Having very cursory knowledge of electronics, I'm extremely confused by this statement I took from the Arduino Knock example: Additionally, connect a 1-megohm resistor in parallel to the Piezo element to limit the voltage and current produced by the piezo and to protect the analog input.

In my case I use the IRLZ44 NPN MOSFET as low-side transistor to control the buzzer. JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. The 1M resistor is connected in parallel to the piezo element to limit current (and voltage) produced by the piezoelectric element, while the zener diode ensures that the output voltage is effectively clamped to 5V. The solution is to use a transistor and divide between the control signal and the power consumption. One way to do this is using the simple circuit below. But if we want to use magnetic buzzers with a current consumption higher than 20mA we have to find a different power supply than the digital I/O pin of the microcontroller. Piezo buzzer have a current consumption lower than 20mA and could therefore be powered by Arduino microcontroller as well as the ESP32.