Sound-Frequency

Tone generator for pi

Speaker-test is already installed by default:

//Code

:

speaker-test -X -f 35000 -t sine

speaker-test -X -f 1000 -t sine

Here's how to generate frequencies using a Raspberry Pi and Python:

• Using RPi.GPIO Library (PWM):

  • This method leverages the Raspberry Pi's hardware-based Pulse Width Modulation (PWM) capabilities.
    It's suitable for generating relatively low frequencies (up to a few kHz).
    Connect an LED or oscilloscope to a GPIO pin (e.g., GPIO18, which supports hardware PWM).
    Use the RPi.GPIO library in Python to control the PWM output.

../code

import RPi.GPIO as GPIO

import time

# Set up GPIO mode and pin

GPIO.setmode(GPIO.BCM)

pwm_pin = 18  # GPIO18

GPIO.setup(pwm_pin, GPIO.OUT)

# Create PWM instance (frequency in Hz)

frequency = 1000  # 1 kHz

pwm = GPIO.PWM(pwm_pin, frequency)

# Start PWM with 50% duty cycle

duty_cycle = 50

pwm.start(duty_cycle)

try:

    while True:

        # Change frequency (optional)

        # frequency = 2000

        # pwm.ChangeFrequency(frequency)

        # Change duty cycle (optional)

        # duty_cycle = 75

        # pwm.ChangeDutyCycle(duty_cycle)

        time.sleep(0.1)

except KeyboardInterrupt:

    pwm.stop()

    GPIO.cleanup()

../

• Using the rpitx library:

  • This method allows for generating radio frequencies (RF) without additional hardware
    It can handle frequencies from 5 kHz up to 1500 MHz.
    Install rpitx using:

  • ../code
    sudo apt update

  •     sudo apt install -y git

  •     git clone https://github.com/F5OEO/rpitx.git

  •     cd rpitx

  •     make install

• .//
  Run rpitx from the command line to generate signals. For example, to generate a 100 MHz sine wave:
  ../
  sudo rpitx -m RF -f 100000
  ..//

• Software-based frequency generation (simpler, less accurate):

  • This method uses delays in the code to approximate a frequency.
    It is less accurate and less stable than hardware PWM.
    Connect an LED or oscilloscope to a GPIO pin.

../code
import RPi.GPIO as GPIO

import time

GPIO.setmode(GPIO.BCM)

output_pin = 17

GPIO.setup(output_pin, GPIO.OUT)

def generate_square_wave(frequency):

    period = 1.0 / frequency

    half_period = period / 2.0

    while True:

        GPIO.output(output_pin, GPIO.HIGH)

        time.sleep(half_period)

        GPIO.output(output_pin, GPIO.LOW)

        time.sleep(half_period)

try:

    generate_square_wave(100)  # 100 Hz

except KeyboardInterrupt:

    GPIO.cleanup()