Merge pull request #133 from gregsyoung/notifications

Notifications Blog

Author: bkeepers

_posts/2025/signalk-Local-Remote-Alerts.mdx

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+---
+publishDate: 2025-10-27
+title: SignalK Remote Alerting with Pushover and a Local Beeper
+author: Greg Young
+image: ~/assets/images/signalk-notifications.webp
+category: Tutorial
+tags: [pushover, signalk, Node-RED]
+excerpt: An example of using Pushover for signalK remote notifications across Android and IOS devices; and an inexpensive beeper locally that will ensure it wakes you in the middle of the night.
+---
+
+## 1. Background
+
+With extensive monitoring capabilities built into my signalK system, I wanted a method to provide "remote" notifications/alarms of selected events, so that when remote from the boat.. even on the other side of the world traveling, I could receive alerts on my Android phone & Ipad (IOS), thus demanding a common method across both mobile device operating systems.
+SignalK has a built in "notification engine" that requires a display device, or application/plugin to handle these, and in turn trigger audible & visual alerts.
+There are two basic use cases, namely "Locally" (on the boat) or "Remote" (which could be "at the beach", or "on the other side of the world").
+This list is certainly not exhaustive, just based on my experience.
+
+**Local Alerts**:
+
+- audible alerts from sound devices such as USB speakers, audio output (from RPi) to a local stereo (eg Fusion)
+- audible alert beeper/buzzer/siren device (eg driven by RPi GPIO)
+- Displays devices such as MFDs, monitor/touchscreen
+- Tablet/phones or PCs running applications (eg WilhelmSK, KIP, OpenCPN)
+- **Remote Alerts**:
+- Any of the above applications that can be operated on a mobile device AND support "remote push" style alerts
+- Cloud based "push" messaging (eg Pushover, SMS)
+
+I have tried a number of these methods, and settled upon using Pushover for remote alerts and an onboard "beeper" for local alerts.
+
+## 2. SignalK Notification Types
+
+Within signalK there are four pre-defined notification "types" (levels) namely;
+
+- Emergency
+- Alarm
+- Warning
+- Alert
+
+Different plugins, actions & user defined NodeRed flows can selectively raise or cancel (set to "normal") & respond to these notifications.
+For example, the anchor alarm plugin generates an "Emergency" notification for breaching the alarm radius (configurable in the plugin) and a "Warning" for the inner radius.
+The audible &/or visual behavior of a client would typically be different for an "alert" vs a "warning" vs an "emergency".
+
+## 3. Remote Pushover notifications
+
+Pushover is a cloud based notification platform that makes it easy to get real-time notifications on your Android, iPhone, iPad, Desktop or watch (Android Wear and Apple Watch)
+[https://pushover.net/](https://pushover.net/)
+
+Use of the messaging platform is "free" (up to 100k notifications/mth), however the android and IOS apps (each) have a one time fee of $5.
+After registering (free), you will be assigned a "username" & "API key, these are used below.
+
+## 4. Install & Setup signalK Pushover Plugin
+
+Install the signalk pushover plugin
+[install pushover plugin](https://github.com/KvotheBloodless/signalk-pushover-notification-relay)
+from the signalk app store and then configure with your username/API Key.
+If you leave the Notification section blank, it will send ALL signalK notifications.
+
+![alt text](../../public/images/posts/signalk-remote-local-alerts/pushover-plugin-setup.webp)
+
+## 5. Pushover IOS (iphone/Ipad) application
+
+Install pushover application on your mobile device (IOS version shown), and customise it as required.
+It enables customisation of sounds and behavior, it will "wake" the device (& can over-ride silent modes etc) with different tones and volume (inc very loud!) alerting... you certainly cant miss them!
+
+![alt text](../../public/images/posts/signalk-remote-local-alerts/pushover-ipad-app-config.webp)
+
+An example of a pushover message, for an "emergency" notification (anchor alarm radius exceeded); which continues until acknowledged.
+Its all very highly customizable.
+
+An example of what the application screen looks like.
+![alt text](../../public/images/posts/signalk-remote-local-alerts/pushover-alerts2.webp)
+
+An emergency alert; note the "acknowledge notification" that needs to be clicked to stop it repeatedly alerting.
+
+![alt text](../../public/images/posts/signalk-remote-local-alerts/pushover-alerts.webp)
+
+## 6. Beeper for Local alerts
+
+Everyone has heard those annoying "reversing beepers" on trucks, with a distinctive screech, they are inexpensive & readily available in either 12V or 24V. This is a perfect solution for hiding out of sight, but still loud enough to get my attention anywhere on the boat, including waking me in the master stateroom.
+
+![alt text](../../public/images/posts/signalk-remote-local-alerts/beeper-horn.webp)
+
+12/24V Backup Beeper Horn 105dB ~$15
+
+Whilst there are very cheap "5V buzzer" devices available that can be driven directly from a RPI; in my experience their sound level is inadequate.
+My RPi that hosts signalK is "always running", so an externally connected "beeper" has advantages:
+
+- no additional power draw (except when alerting)
+- does not require running chartplotter/MFDs or sound system (overnight or when at anchor)
+- will operate regardless even when Ipad/phone are flat; or not connected to the boat LAN
+  .. or inevitably in a location where the inbuilt sound level just doesn't do the job.
+
+## 7. Driving the Beeper from a RPi
+
+Operating from 12 or 24V power, the beeper cannot be directly powered or driven by the RPi.
+To operate the beeper, a separate "relay module" is used, that can be driven directly from a RPi GPIO.
+
+![alt text](../../public/images/posts/signalk-remote-local-alerts/5V-relay-module.webp)
+5V one channel relay board with optocoupler (high and low level trigger) ~$2
+
+Its preferable to have a module that has a "high trigger" capability, as this is then driven "active" by a GPIO "high" level output.
+
+## 8. Beeper & Relay circuit diagram
+
+![alt text](../../public/images/posts/signalk-remote-local-alerts/signalk-Rpi-local-beeper.webp)
+
+## 9. Node-Red alerting
+
+![alt text](../../public/images/posts/signalk-remote-local-alerts/nodered-notifications-beeper.webp)
+
+This NodRed flow can be downloaded atp:
+[Download the Node-Red flow](https://github.com/gregsyoung/NodeRed-Flows/blob/main/notifications-beeper/NodeRed-alerting-beeper.json)
+
+To control the beeper, we use a "rpi-gpio out node" (in this case connected to Pin40 /GPIO21), when msg.payload =1, the relay module is switched ON and the beeper sounds.
+There are two different sub flows, the upper pulses the beeper (1.2S ON/ 1 S off) continuously when either "emergency" or "alarm" notifications are set (for any path). The lower sub flow (for "alerts") sounds a double beep only.
+In this flow as configured, ALL notifications of the respective type initiate the beeper sounding, however the "notification node" can be configured for a single path only if desired.
+In practice, in my system, any notification of type "emergency or alarm" result in an ongoing (very loud) beeping until the alarm is cleared (set to "normal" in signalK).
+
+## 10. Summary
+
+Deploying inexpensive hardware and some simple NodeRed flows, I created a local audible alarm system, with different alerting depending on the urgency; that has the capability to wake me as required and be heard around all areas of the boat.
+For remote alerting with a high level of customisation, the Pushover plugin/cloud service with its mobile application has worked reliably for me "across the world" to receive urgent alerts of unexpected events on the boat.