Overview
The buzzer node controls both active and passive piezo buzzers for generating
audio alerts, notification tones, and alarm sounds. Active buzzers produce a fixed tone with a simple on/off signal,
while passive buzzers allow frequency control for melodies and variable tones. Supports timed beeps with configurable
duration for precise audio feedback in IoT systems.
Active vs Passive Buzzers
Active Buzzer
- Built-in oscillator circuit
- Fixed frequency tone (~2.7kHz)
- Simple on/off control (HIGH/LOW)
- No PWM required
- Best for simple alerts and alarms
Passive Buzzer
- No internal oscillator
- Variable frequency via PWM
- Can play melodies and tones
- Requires PWM signal input
- Best for custom tones and music
Properties
| Property | Type | Required | Default | Description |
|---|---|---|---|---|
| pin | number | Yes | 18 | GPIO pin number (BCM numbering) |
| type | select | No | "active" | Buzzer type: "active" or "passive" |
| frequency | number | No | 1000 | Default tone frequency in Hz (passive only) |
| activeLow | boolean | No | false | Invert logic for active-low buzzer modules |
| duration | number | No | 100 | Default beep duration in milliseconds |
Inputs
Object with action, optional frequency and duration.
{
"action": "beep",
"frequency": 2000,
"duration": 200
}"beep" Sound for specified duration then stop "on" Turn buzzer on continuously "off" Turn buzzer off Outputs
Outputs current buzzer state with configuration.
{
"state": "beep",
"type": "passive",
"frequency": 2000,
"duration": 200,
"timestamp": 1709251200000
}Wiring / Connection Diagram
Active Buzzer (Direct)
Raspberry Pi Active Buzzer
+-----------+ +-----------+
| | | (+) |
| GPIO 18 |--------| Signal |
| | | |
| GND |--------| GND (-) |
| | +-----------+
+-----------+
Note: Active buzzers have a
built-in oscillator. Just send
HIGH to activate.Passive Buzzer (with Transistor)
Raspberry Pi NPN Transistor
+-----------+ +------+
| | 1kΩ | B | Passive Buzzer
| GPIO 18 |--[R]---| NPN | +----------+
| | | C |---| (+) |
| GND |--------| E | | |
+-----------+ +------+ | GND (-) |
+----------+
| |
[GND] [3.3V/5V]
Note: Transistor needed for
passive buzzers to provide
sufficient current.Example Use Cases
Temperature Alarm
Sound an alarm when temperature exceeds a critical threshold.
[
{
"id": "temp-sensor",
"type": "dht22",
"pin": 4,
"interval": 5000
},
{
"id": "threshold-check",
"type": "switch",
"property": "payload.temperature",
"rules": [
{ "t": "gt", "v": "40" }
]
},
{
"id": "alarm-set",
"type": "change",
"rules": [
{ "t": "set", "p": "payload", "to": { "action": "beep", "duration": 500 } }
]
},
{
"id": "alarm-buzzer",
"type": "buzzer",
"pin": 18,
"type": "active",
"duration": 500
}
]Doorbell with Custom Melody
Play a tone sequence using a passive buzzer when a button is pressed.
[
{
"id": "door-button",
"type": "gpio-in",
"pin": 25,
"edge": "rising"
},
{
"id": "melody-gen",
"type": "function",
"func": "// Doorbell ding-dong sequence
var notes = [
{ action: 'beep', frequency: 659, duration: 300 },
{ action: 'beep', frequency: 523, duration: 500 }
];
for (var i = 0; i < notes.length; i++) {
var m = { payload: notes[i] };
node.send(m);
}
return null;"
},
{
"id": "doorbell-buzzer",
"type": "buzzer",
"pin": 18,
"buzzerType": "passive",
"frequency": 1000
}
]Motion Detection Alert
Quick beep notification when motion is detected by a PIR sensor.
[
{
"id": "motion-sensor",
"type": "pir",
"pin": 7,
"retriggerable": false
},
{
"id": "beep-cmd",
"type": "change",
"rules": [
{ "t": "set", "p": "payload", "to": { "action": "beep", "duration": 100 } }
]
},
{
"id": "alert-buzzer",
"type": "buzzer",
"pin": 18,
"buzzerType": "active",
"duration": 100
}
]Common Use Cases
Safety Alarms
Temperature, gas, and intrusion alert systems
Doorbell Systems
Custom tones for visitor notification
Timer Notifications
Audible alerts for scheduled events and timers
User Feedback
Audio confirmation beeps for button presses and actions