4. Buzzer Driver Experiment

Routine Code

from machine import Timer, PWM
import time
from fpioa_manager import fm
from maix import GPIO

# Create Timer 0 Channel 0 and set to PWM mode
tim = Timer(Timer.TIMER0, Timer.CHANNEL0, mode=Timer.MODE_PWM)

# Configure PWM: frequency 500, initial duty cycle 100, pin 9
ch = PWM(tim, freq=500, duty=100, pin=9)

# CanMV board pin configuration
fm.register(11, fm.fpioa.GPIOHS11, force=True)
fm.register(12, fm.fpioa.GPIOHS12, force=True)
fm.register(13, fm.fpioa.GPIOHS13, force=True)
fm.register(16, fm.fpioa.GPIOHS16, force=True)

# Configure pins as input
key1 = GPIO(GPIO.GPIOHS11, GPIO.IN)
key2 = GPIO(GPIO.GPIOHS12, GPIO.IN)
key3 = GPIO(GPIO.GPIOHS13, GPIO.IN)
key4 = GPIO(GPIO.GPIOHS16, GPIO.IN)

# Define four different sound frequencies
freq1 = 500
freq2 = 1000
freq3 = 1500
freq4 = 2000

def play_sound(frequency):
    ch.freq(frequency)
    ch.duty(10)  # Adjust duty cycle to control volume

while True:

    # Check if button 1 is pressed
    if not key1.value():
        play_sound(freq1)
        time.sleep_ms(100)  # Brief delay to avoid rapid polling
    # Check if button 2 is pressed
    elif not key2.value():
        play_sound(freq2)
        time.sleep_ms(100)  # Brief delay to avoid rapid polling
    # Check if button 3 is pressed
    elif not key3.value():
        play_sound(freq3)
        time.sleep_ms(100)  # Brief delay to avoid rapid polling
    # Check if button 4 is pressed
    elif not key4.value():
        play_sound(freq4)
        time.sleep_ms(100)  # Brief delay to avoid rapid polling

Experiment Preparation

1. Connect the K210 to your computer via USB.
1. Open CanMV IDE, connect to the K210, and run the routine code above.

Experiment Results

1. After running, press any of the four buttons on top of the K210. The K210 plays the corresponding tone continuously. Each button produces a different sound. Press the reset button to stop the program.

Routine Code Explanation

1. Import required modules. Timer and PWM from the machine module create a timer and configure pulse-width modulation (PWM), commonly used to control motor speed, LED brightness, and audio signals by varying duty cycle.

from machine import Timer, PWM
import time
from fpioa_manager import fm
from maix import GPIO

1. Create a timer and configure PWM. The Timer class creates timer object tim using TIMER0 CHANNEL0 in PWM mode. The PWM object ch is created with frequency 500 Hz, initial duty cycle 100%, and output on pin 9. This PWM signal can drive devices such as a buzzer.

tim = Timer(Timer.TIMER0, Timer.CHANNEL0, mode=Timer.MODE_PWM)
ch = PWM(tim, freq=500, duty=100, pin=9)

1. Board pin configuration. Same as the button experiment; not described in detail here.

fm.register(11, fm.fpioa.GPIOHS11, force=True)
fm.register(12, fm.fpioa.GPIOHS12, force=True)
fm.register(13, fm.fpioa.GPIOHS13, force=True)
fm.register(16, fm.fpioa.GPIOHS16, force=True)

key1 = GPIO(GPIO.GPIOHS11, GPIO.IN)
key2 = GPIO(GPIO.GPIOHS12, GPIO.IN)
key3 = GPIO(GPIO.GPIOHS13, GPIO.IN)
key4 = GPIO(GPIO.GPIOHS16, GPIO.IN)

1. Define four variables freq1, freq2, freq3, and freq4 representing four sound frequencies in Hz. These change the PWM frequency to produce different tones on the device connected to pin 9.

freq1 = 500
freq2 = 1000
freq3 = 1500
freq4 = 2000

1. Define play_sound(frequency) to set the PWM frequency via ch.freq(frequency) and adjust volume with ch.duty(10) (10% duty cycle for moderate volume).

def play_sound(frequency):
    ch.freq(frequency)
    ch.duty(10)

1. Enter an infinite loop that continuously checks whether each button is pressed. When a button is pressed (low level), call play_sound with the corresponding frequency.

while True:

    # Check if button 1 is pressed
    if not key1.value():
        play_sound(freq1)
        time.sleep_ms(100)  
    # Check if button 2 is pressed
    elif not key2.value():
        play_sound(freq2)
        time.sleep_ms(100)  
    # Check if button 3 is pressed
    elif not key3.value():
        play_sound(freq3)
        time.sleep_ms(100)  
    # Check if button 4 is pressed
    elif not key4.value():
        play_sound(freq4)
        time.sleep_ms(100)