Google Voice Kit Raspberry Pi Voice HAT ALSA GPIO

Reviving and Configuring Google Voice Kit V1 Basic Hardware

Reviving and Configuring Google Voice Kit V1 Basic Hardware

By Pixel Li · March 8, 2026

中文原文 →

Supported environment:

  • Hardware: Raspberry Pi + Google Voice Kit V1 (Voice HAT expansion board)
  • OS: Raspberry Pi OS (based on Debian Bookworm or newer, kernel 6.x+)

1. Enable the low-level hardware driver

The device tree config file on modern Raspberry Pi systems has moved to the /boot/firmware/ directory. You need to disable the default onboard audio and load the Voice HAT-specific driver.

Steps: Edit the config file:

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sudo nano /boot/firmware/config.txt

Make these two changes:

  1. Comment out the default audio line (if present):
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#dtparam=audio=on
  1. Append the Voice HAT device tree overlay directive to the end of the file:
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dtoverlay=googlevoicehat-soundcard

Save and exit (Ctrl+O, Enter, Ctrl+X), then reboot the system:

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sudo reboot

2. Verify the sound card and get the device number

After rebooting, confirm that the system has correctly detected the Voice HAT hardware.

Steps: List the audio devices:

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aplay -l

Expected output: Look for an entry that contains snd_rpi_googlevoicehat_soundcard. Note the corresponding card number (e.g. card 1 or card 0). The configuration below uses card 1 as an example.

3. Configure global ALSA audio routing

By defining a user-level ALSA config file, you force the system to use the Voice HAT as the global default audio input/output device, and use the plug plugin to handle audio resampling automatically.

Steps: Create or edit the ALSA configuration file for the current user:

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nano ~/.asoundrc

Write the following configuration (make sure to replace the 1 in hw:1,0 and card 1 with the actual card number obtained in the previous step):

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pcm.!default {
    type plug
    slave.pcm "hw:1,0"
}

ctl.!default {
    type hw
    card 1
}

Save and exit. The system’s basic audio layer is now configured.

4. Install dependencies and write the MVP script

The Voice HAT’s button and LED are connected directly to the Raspberry Pi’s standard GPIO pins (button = GPIO 23, LED = GPIO 25). Use the gpiozero library to control them.

Steps: Install the necessary Python dependencies:

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sudo apt update
sudo apt install python3-gpiozero

Create the test script:

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nano voice_mvp.py

Enter the following code:

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from gpiozero import Button, LED
from signal import pause
import subprocess

# Voice HAT V1 hardware pin definitions
BUTTON_PIN = 23  
LED_PIN = 25     
# System audio file for testing
AUDIO_FILE = "/usr/share/sounds/alsa/Front_Center.wav" 

button = Button(BUTTON_PIN)
led = LED(LED_PIN)

def on_button_pressed():
    print("[Event] Button Pressed")
    led.on()
    
    try:
        # Since ~/.asoundrc is already configured, no device parameters are needed here
        subprocess.run(["aplay", AUDIO_FILE])
    except Exception as e:
        print(f"[Error] Audio playback failed: {e}")
        
    led.off()
    print("[Status] Playback complete. Awaiting next trigger.")

# Bind the button event
button.when_pressed = on_button_pressed

print("[System] Initialization complete. Listening for hardware interrupts...")
pause()

5. Run the test

Run the script:

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python3 voice_mvp.py

Test criteria: Press the physical button on top of the device; the LED indicator lights up, the speaker plays the “Front Center” audio, then the LED turns off and the terminal prints the corresponding log messages.

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