Arduino UNO Q - Buzzer
A 12V active buzzer produces a loud sound — ideal for alarms and alerts. Because it requires 12V, it cannot be powered directly from the Arduino UNO Q. Instead, a relay acts as a switch that the Arduino controls. In this tutorial, you will learn how to wire a 12V active buzzer to Arduino UNO Q via a relay and control it locally and remotely via Telegram.
Hardware Preparation
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Overview of 12V Active Buzzer
A 12V active buzzer produces a loud continuous sound when 12V is applied — no frequency signal needed.
Pinout
- Positive (+) pin (red): Connect to 12V power supply (via relay)
- Negative (−) pin (black): Connect to GND of the 12V power supply
How to Control It with Arduino UNO Q
Because the buzzer requires 12V and Arduino UNO Q outputs 3.3V, a relay is needed:
- The Arduino UNO Q controls the relay coil (3.3V-compatible signal)
- The relay switches the 12V line to the buzzer ON or OFF
- If you are unfamiliar with relays, see Arduino UNO Q - Relay tutorial first
Wiring Diagram
This image is created using Fritzing. Click to enlarge image
MCU Code
The Arduino UNO Q has two processors: the STM32 MCU (handles real-time hardware control) and the Qualcomm MPU (runs Debian Linux). In this section, only the STM32 MCU is programmed — the Linux side stays idle. A later section will show how both processors work together.
The code turns the 12V buzzer ON for 2 seconds and OFF for 5 seconds, repeating continuously:
/*
* This Arduino UNO Q code was developed by newbiely.com
*
* This Arduino UNO Q code is made available for public use without any restriction
*
* For comprehensive instructions and wiring diagrams, please visit:
* https://newbiely.com/tutorials/arduino-uno-q/arduino-uno-q-buzzer
*/
#define RELAY_PIN 3 // pin connected to the relay that controls the 12V buzzer
void setup() {
pinMode(RELAY_PIN, OUTPUT);
}
void loop() {
digitalWrite(RELAY_PIN, HIGH); // turn buzzer ON via relay
delay(2000);
digitalWrite(RELAY_PIN, LOW); // turn buzzer OFF via relay
delay(5000);
}
Detailed Instructions
- First time with Arduino UNO Q? Follow the Getting Started with Arduino UNO Q tutorial to get your development environment ready before proceeding.
- Wire the components: Connect the relay signal pin to pin 3, wire the relay to the 12V buzzer and 12V power supply as shown in the diagram.
- Connect: Plug the Arduino UNO Q into your computer with a USB-C cable.
- Open Arduino App Lab: Launch Arduino App Lab and wait until it detects your Arduino UNO Q.
- Create a new App: Click the Create New App button.
- Give the App a name, for example: DIYables_Buzzer12V
- Click Create to confirm.
- You will see a set of folders and files generated inside your new App.
- Find the sketch/sketch.ino file — this is where you will paste the MCU sketch.
Paste the sketch: Copy the MCU code above and paste it into the sketch file. Keep other files as default.
- Install the library: Click the Add sketch library button (the open book icon with a + sign) in the left sidebar.
- Search for Arduino_RouterBridge created by Arduino and click the Install button.
Bricks
No bricks added...
Sketch Libraries
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Files
python
sketch
.gitignore
README.md
app.yaml
sketch.ino
- Upload: Click the Run button in Arduino App Lab to compile and upload to the STM32.
- Listen: The buzzer turns ON for 2 seconds, then OFF for 5 seconds, repeating continuously.
Linux + MCU Bridge Programming
The Arduino UNO Q has two processors that work together: the MPU (Qualcomm, runs Debian Linux) and the MCU (STM32, runs Zephyr OS with your Arduino sketch). They communicate using RPC via the Arduino_RouterBridge library — never via raw serial ports.
- The relay is connected to the MCU (STM32) — wired to a digital output pin. The MCU drives the relay HIGH/LOW to control the 12V buzzer.
- The MPU cannot control the relay directly — it must call a function on the MCU via Bridge.call() to turn the buzzer ON or OFF.
- The MPU has Wi-Fi — because the MPU runs full Debian Linux with Wi-Fi, it can receive Telegram commands and remotely trigger the buzzer.
- Communication: Bridge.call() on the Linux side invokes Bridge.provide_safe() functions on the MCU side (since digitalWrite() is a hardware API)
- ⚠️ Reserved: /dev/ttyHS1 (Linux) and Serial1 (MCU) are used by the Arduino Router — never open them directly
In short: MPU sends on/off command → MCU drives relay → relay switches 12V buzzer.
MCU sketch — relay-controlled buzzer with Bridge and Monitor output:
/*
* This Arduino UNO Q code was developed by newbiely.com
*
* This Arduino UNO Q code is made available for public use without any restriction
*
* For comprehensive instructions and wiring diagrams, please visit:
* https://newbiely.com/tutorials/arduino-uno-q/arduino-uno-q-buzzer
*/
#include "Arduino_RouterBridge.h"
#define RELAY_PIN 3
void buzzer_on() {
digitalWrite(RELAY_PIN, HIGH);
Monitor.println("Buzzer ON");
}
void buzzer_off() {
digitalWrite(RELAY_PIN, LOW);
Monitor.println("Buzzer OFF");
}
void setup() {
Bridge.begin();
Monitor.begin();
pinMode(RELAY_PIN, OUTPUT);
digitalWrite(RELAY_PIN, LOW);
Bridge.provide_safe("buzzer_on", buzzer_on);
Bridge.provide_safe("buzzer_off", buzzer_off);
Monitor.println("12V Buzzer Bridge ready");
}
void loop() {}
Python script (Arduino App Lab) — control buzzer from Linux:
/*
* This Arduino UNO Q code was developed by newbiely.com
*
* This Arduino UNO Q code is made available for public use without any restriction
*
* For comprehensive instructions and wiring diagrams, please visit:
* https://newbiely.com/tutorials/arduino-uno-q/arduino-uno-q-buzzer
*/
from arduino.app_utils import *
import time
def loop():
print("Turning buzzer ON")
Bridge.call("buzzer_on")
time.sleep(2)
print("Turning buzzer OFF")
Bridge.call("buzzer_off")
time.sleep(5)
App.run(user_loop=loop)
- Note: Make sure Bridge.begin() is called in the MCU sketch and the sketch is uploaded before running the Python script on the Linux side.
- ⚠️ Warning: Never directly open /dev/ttyHS1 (on Linux) or use Serial1 (on MCU) in your code — these are reserved by the Arduino Router and accessing them will break the Bridge.
Detailed Instructions
- Upload the MCU sketch: Open Arduino App Lab, create a new App, paste the Bridge MCU sketch into sketch/sketch.ino, install the Arduino_RouterBridge library, and click Run.
- Add the Python script: Paste the Python code above into the Python tab of the same App.
- Run the App: Click Run — Python cycles the buzzer ON for 2 s and OFF for 5 s automatically.
- Check the console: Open the Console tab → MCU Monitor subtab to see "Buzzer ON" and "Buzzer OFF" messages.
App Lab Console Output
sketch.ino
1#include "Arduino_RouterBridge.h"
Serial Monitor
Python
12V Buzzer Bridge ready
Buzzer ON
Buzzer OFF
Buzzer ON
Telegram Integration
Control the 12V buzzer remotely from anywhere via Telegram.
If you do not have a Telegram bot yet, see How to Create a Telegram Bot to get your bot token before continuing.
MCU sketch: Keep the same MCU sketch from the previous Bridge section — no changes needed. Make sure it is already uploaded and running on the STM32 before proceeding.
Python script (Arduino App Lab) — Telegram bot for 12V buzzer control:
/*
* This Arduino UNO Q code was developed by newbiely.com
*
* This Arduino UNO Q code is made available for public use without any restriction
*
* For comprehensive instructions and wiring diagrams, please visit:
* https://newbiely.com/tutorials/arduino-uno-q/arduino-uno-q-buzzer
*/
from arduino.app_utils import *
import requests
import time
BOT_TOKEN = "YOUR_BOT_TOKEN"
API_URL = f"https://api.telegram.org/bot{BOT_TOKEN}"
last_update_id = 0
def send_message(chat_id, text):
requests.post(f"{API_URL}/sendMessage", json={"chat_id": chat_id, "text": text})
def get_updates():
global last_update_id
resp = requests.get(f"{API_URL}/getUpdates", params={"offset": last_update_id + 1, "timeout": 5})
return resp.json().get("result", [])
def loop():
global last_update_id
updates = get_updates()
for update in updates:
last_update_id = update["update_id"]
msg = update.get("message", {})
chat_id = msg.get("chat", {}).get("id")
text = msg.get("text", "").strip()
if text == "/on":
Bridge.call("buzzer_on")
send_message(chat_id, "Buzzer is ON.")
elif text == "/off":
Bridge.call("buzzer_off")
send_message(chat_id, "Buzzer is OFF.")
else:
send_message(chat_id, "Commands:\n/on — turn buzzer ON\n/off — turn buzzer OFF")
time.sleep(1)
App.run(user_loop=loop)
- Note: Replace YOUR_BOT_TOKEN with the token obtained from @BotFather on Telegram.
- Send /on to turn the buzzer ON.
- Send /off to turn the buzzer OFF.
Detailed Instructions
- Upload the MCU sketch: Use the Bridge MCU sketch from the previous section (upload it first if not already done).
- Paste the Telegram script: Copy the Python code above into the Python tab of your App in Arduino App Lab.
- Set your token: Replace YOUR_BOT_TOKEN in the script with your actual bot token.
- Run the App: Click Run — the bot starts listening for Telegram messages.
- Test it: Send /on — hear the buzzer turn on. Send /off — confirm it stops.
App Lab Console Output
sketch.ino
1#include "Arduino_RouterBridge.h"
Serial Monitor
Python
[2026-04-29 12:00:01] Telegram: /on
[2026-04-29 12:00:01] Buzzer is ON.
[2026-04-29 12:02:10] Telegram: /off
[2026-04-29 12:02:10] Buzzer is OFF.
Telegram
12:45
Welcome to Telegram!
ArduinoBot
10:19
Chatting with Arduino...
BotFather
Yesterday
Your bot has been created.
ArduinoBot
bot
OpenClaw Integration
OpenClaw integration for Arduino UNO Q 12V buzzer control is coming soon.
- Coming Soon: OpenClaw support for controlling a 12V active buzzer on Arduino UNO Q will be covered in a future update.
Application/Project Ideas
- Remote alarm: Trigger a loud 12V alarm from anywhere via Telegram when a security event occurs
- Timed alert: Use the MPU's Linux clock to sound the buzzer at a scheduled time
- Door security alarm: Pair with a motion sensor — sound the buzzer when motion is detected unexpectedly
- Process completion alert: Sound the buzzer when a long-running process (e.g., 3D print, oven timer) finishes
- Perimeter warning: Use multiple relay channels to control several buzzers in different zones
Challenge Yourself
- Easy: Add a /status command that reports whether the buzzer is currently ON or OFF
- Medium: Add a /beep <count> Telegram command that beeps the buzzer N times with a 1-second interval
- Advanced: Build a Telegram-controlled countdown alarm — schedule a buzzer trigger time from Telegram and have the MPU sound it automatically