reterminal-dm4/chromium-setup/BUZZER-CONTROL.md

Buzzer Control - reTerminal DM4

Quick Reference

Device Path: /sys/class/leds/usr-buzzer/brightness

Basic Commands

# Turn ON
echo 1 | sudo tee /sys/class/leds/usr-buzzer/brightness

# Turn OFF
echo 0 | sudo tee /sys/class/leds/usr-buzzer/brightness

# Check Status
cat /sys/class/leds/usr-buzzer/brightness  # 0=OFF, 1/255=ON

Single Beep

echo 1 | sudo tee /sys/class/leds/usr-buzzer/brightness
sleep 0.2
echo 0 | sudo tee /sys/class/leds/usr-buzzer/brightness

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Test Scripts

Bash Script

Location on device: /home/pi/buzzer/test_buzzer.sh

Run:

ssh guard "/home/pi/buzzer/test_buzzer.sh"
# or
/home/pi/buzzer/test_buzzer.sh

Tests included:

• Single beep
• Double beep
• Triple beep
• Long beep
• Rapid beeps
• Slow beeps
• Success pattern
• Error pattern

Python Script

Location on device: /home/pi/buzzer/test_buzzer.py

Run:

ssh guard "python3 /home/pi/buzzer/test_buzzer.py"
# or
python3 /home/pi/buzzer/test_buzzer.py

Same tests as bash script, with Python implementation

---

Python Control

import subprocess
import time

BUZZER = '/sys/class/leds/usr-buzzer/brightness'

def buzzer_on():
    subprocess.run(['sudo', 'tee', BUZZER], input='1', text=True)

def buzzer_off():
    subprocess.run(['sudo', 'tee', BUZZER], input='0', text=True)

def beep(duration=0.2):
    buzzer_on()
    time.sleep(duration)
    buzzer_off()

# Usage
beep(0.2)  # Short beep
beep(0.5)  # Long beep

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Common Patterns

Success Alert (2 short beeps)

for i in 1 2; do
    echo 1 | sudo tee /sys/class/leds/usr-buzzer/brightness
    sleep 0.1
    echo 0 | sudo tee /sys/class/leds/usr-buzzer/brightness
    sleep 0.1
done

Error Alert (3 fast beeps)

for i in 1 2 3; do
    echo 1 | sudo tee /sys/class/leds/usr-buzzer/brightness
    sleep 0.05
    echo 0 | sudo tee /sys/class/leds/usr-buzzer/brightness
    sleep 0.05
done

Notification (1 short beep)

echo 1 | sudo tee /sys/class/leds/usr-buzzer/brightness
sleep 0.2
echo 0 | sudo tee /sys/class/leds/usr-buzzer/brightness

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Troubleshooting

Buzzer not working?

1. Check device: ls -la /sys/class/leds/usr-buzzer/
2. Test manually: echo 1 | sudo tee /sys/class/leds/usr-buzzer/brightness
3. Verify permissions: Requires sudo

No sound?

• Check if buzzer is physically present
• Try longer duration: sleep 1 instead of sleep 0.2
• Check kernel: dmesg | grep -i buzzer

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Notes

• Requires: sudo privileges
• Type: Simple on/off (no volume/frequency control)
• Location: Bottom right corner of screen
• Use: Alerts, notifications, system events

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Related Files

• Test scripts: /home/pi/buzzer/test_buzzer.sh (bash), /home/pi/buzzer/test_buzzer.py (Python)
• Detailed guide: BUZZER-CONTROL-SIMPLE.md
• Flask API: FLASK-BUZZER-CONTROL.md