1.2.1 Active Buzzer¶

Introduction¶

In this project, we will learn how to drive an active buzzer to beep with a PNP transistor.

Required Components¶

In this project, we need the following components.

Schematic Diagram¶

In this experiment, an active buzzer, a PNP transistor and a 1k resistor are used between the base of the transistor and GPIO to protect the transistor. When the GPIO17 of Raspberry Pi output is supplied with high level (3.3V) by programming, the transistor will conduct because of current saturation and the buzzer will make sounds. But when low level is supplied to the IO of Raspberry Pi, the transistor will be cut off and the buzzer will not make sounds.

T-Board Name	physical	wiringPi	BCM
GPIO17	Pin 11	0	17

../_images/1.2.1_active_buzzer_schematic.png

Experimental Procedures¶

Step 1: Build the circuit. (The active buzzer has a white table sticker on the surface and a black back.)

../_images/1.2.1_ActiveBuzzer_circuit.png

Step 2: Open the code file.

cd ~/davinci-kit-for-raspberry-pi/python-pi5

Step 3: Run.

sudo python3 1.2.1_ActiveBuzzer_zero.py

The code run, the buzzer beeps.

Code

Note

You can Modify/Reset/Copy/Run/Stop the code below. But before that, you need to go to source code path like davinci-kit-for-raspberry-pi/python-pi5. After modifying the code, you can run it directly to see the effect.

#!/usr/bin/env python3
from gpiozero import Buzzer
from time import sleep

# Initialize a Buzzer object on GPIO pin 17
buzzer = Buzzer(17)

try:
    while True:
        # Turn on the buzzer
        print('Buzzer On')
        buzzer.on()
        sleep(0.1)  # Keep the buzzer on for 0.1 seconds

        # Turn off the buzzer
        print('Buzzer Off')
        buzzer.off()
        sleep(0.1)  # Keep the buzzer off for 0.1 seconds

except KeyboardInterrupt:
    # Handle KeyboardInterrupt (Ctrl+C) for clean script termination
    pass

Code Explanation

These statements import the Buzzer class from the gpiozero library and the sleep function from the time module.
```
#!/usr/bin/env python3
from gpiozero import Buzzer
from time import sleep
```
This line creates a Buzzer object connected to GPIO pin 17 on the Raspberry Pi.
```
# Initialize a Buzzer object on GPIO pin 17
buzzer = Buzzer(17)
```

In an infinite loop (while True), the buzzer is turned on and off every 0.1 seconds. print statements provide a console output for each action.

try:
    while True:
        # Turn on the buzzer
        print('Buzzer On')
        buzzer.on()
        sleep(0.1)  # Keep the buzzer on for 0.1 seconds

        # Turn off the buzzer
        print('Buzzer Off')
        buzzer.off()
        sleep(0.1)  # Keep the buzzer off for 0.1 seconds

This segment ensures the program can be terminated safely using a keyboard interrupt (Ctrl+C) without throwing an error.
```
except KeyboardInterrupt:
# Handle KeyboardInterrupt (Ctrl+C) for clean script termination
pass
```