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External Notification Module Configuration

The External Notification Module will allow you to connect a buzzer, speaker, LED, or other device to notify you when a message has been received from the mesh network. You can enable up to 3 pins independently from each other.

The External Notification Module config options are: Enabled, Active, Alert Bell (General),Alert Bell Vibra, Alert Bell Buzzer, Alert Message (General), Alert Message Vibra, Alert Message Buzzer, Output (General), Output Vibra, Output Buzzer, Output Milliseconds, Use PWM, and Nag Timeout. External Notification config uses an admin message sending a ConfigModule.ExternalNotificationConfig protobuf.

External Notification Module Config Values


Enables the external notification module.

Active (general / LED only)

Specifies whether the external circuit is active when the device's GPIO is low or high. If this is set true, the pin will be pulled active high, false means active low.

Alert when receiving a bell (general / LED, Vibra and Buzzer)

Specifies if an alert should be triggered when receiving an incoming bell.

Alert when receiving a message (general / LED, Vibra and Buzzer)

Specifies if an alert should be triggered when receiving an incoming message.

GPIO Pins (general / LED, Vibra and Buzzer)

Specifies the GPIO that your external circuit is attached to on the device. On devices that have a PWM buzzer, you can use the buzzer for notifications by setting the use_pwm property to TRUE. The Buzzer Pin will be ignored and the device.buzzer_gpio is used instead. If you enable PWM mode, the device will use so-called RTTTL ring tones for notification. You can find examples of RTTTL ring tones here and upload them to the device via a client application.


On ESP32 based boards, GPIOs 34 to 39 are GPIs – input only pins. These pins do not have internal pull-up or pull-down resistors. They can not be used as outputs, so you can NOT use these pins as outputs.

How long monitored GPIO is triggered

Specifies how long in milliseconds you would like your GPIOs to be active. In case of the repeat option, this is the duration of every tone and pause.

Default of 0 is 1000ms

Repeat (Nag Timeout) (general / LED, Vibra and Buzzer)

Specifies if the alert should be repeated. If set to a value greater than zero, the alert will be repeated until the user button is pressed or 'value' number of seconds have past.

External Notification Module Config Client Availability



All external notification module config options are available on iOS, iPadOS and macOS at Settings > Module Configuration > External Notification.


GPIO access is fundamentally dangerous because invalid options can physically damage or destroy your hardware. Ensure that you fully understand the schematic for your particular device before trying this as we do not offer a warranty. Use at your own risk.

This module requires attaching a peripheral accessory to your device. It will not work without one.


Alert Types

We support being alerted on two events:

  1. Incoming Text Message

  2. Incoming Text Message that contains the ASCII bell character. At present, only the Python API can send an ASCII bell character, but more support may be added in the future.


The bell character is ASCII 0x07. Include 0x07 anywhere in the text message and with ext_notification.alert_bell enabled, we will issue an external notification.

External Hardware

Be mindful of the max current sink and source of the ESP32 GPIO. The easiest devices to interface with would be either an LED or Active Buzzer.

Ideas for external hardware:

  • LED
  • Active Buzzer
  • Flame thrower
  • Strobe Light
  • Siren

Known Limitations

  • This module only monitors text messages. We won't trigger on any other packet types.