Raspberry Pi 5 GPIO12 Output PWM Configuration Flow (for Buzzer/LED)

📁 System Configuration Flow

1. Edit Configuration File

Open Configuration File（Raspberry Pi OS usually use /boot/firmware/config.txt）：

sudo nano /boot/firmware/config.txt

2. Add PWM Configuration (⚠️Add at the end of the file, don’t put it in a section like ‘[cm5]’)

dtoverlay=pwm,pin=12,func=4,clock=50000000

• pwm: Represent using single-channel PWM overlay
• pin=12: Select GPIO12（physical pin 32）
• func=4：Select ALT4 mode (PWM0_0 feature of GPIO12)
• clock=50000000：Specifies a PWM input clock of 50MHz

3. Reboot System

sudo reboot

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🧪 PWM Control Command

After rebooting, execute the following commands in turn to enable the PWM signal output (3kHz, 50% duty cycle):

# export pwm0 channel
echo 0 | sudo tee /sys/class/pwm/pwmchip0/export
sleep 0.1

# set PWM parameters
echo 333333 | sudo tee /sys/class/pwm/pwmchip0/pwm0/period
echo 166666 | sudo tee /sys/class/pwm/pwmchip0/pwm0/duty_cycle

# enable PWM output
echo 1 | sudo tee /sys/class/pwm/pwmchip0/pwm0/enable

Example configuration is 3kHz frequency (period 333,333ns), 50% duty cycle (166,666ns)

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✅ Methods for Successful Verification (Optional)

• ✅ The buzzer functions well
• ✅ The LEDs flash or dimly brighten
• ✅ GPIO12 average voltage measured by multimeter ≈ 1.6V (duty cycle 50%)

• ✅ Command ‘gpioinfo

  .’ grep GPIO12’ shows that the pin is in an active or used state

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🛠 Optional: Automation Scripts (enable_pwm12.sh)

#!/bin/bash

echo 0 | sudo tee /sys/class/pwm/pwmchip0/export
sleep 0.1
echo 333333 | sudo tee /sys/class/pwm/pwmchip0/pwm0/period
echo 166666 | sudo tee /sys/class/pwm/pwmchip0/pwm0/duty_cycle
echo 1       | sudo tee /sys/class/pwm/pwmchip0/pwm0/enable

echo "✅ GPIO12 is outputting a 3kHz PWM waveform"

How to use:：

chmod +x enable_pwm12.sh
./enable_pwm12.sh

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