This is the default Mongoose OS app + modified init.js. It's for ringing an IoT bell over MQTT.
For the bell, you can make one with a cheap reception bell and a 5V solenoid. Make sure you use a relay and a relay drive circuit and don't connect the solenoid directly to the GPIO pin.
Change relayPin, topic, or bellNumber if necessary.
- Install and start mos tool
- Switch to the Project page, find and import this app, build and flash it: