Hi everyone!
Here's the power monitor I built for my lab in B4A.
Its fairly simple: if the device gets unplugged (power goes off), it waits for a moment and sends an SMS notification to the specified number. If the power comes back, it also sends a new SMS notification.
We use it in an old phone...
I have been using for a while one app (SENDER) that connects to a Bluetooth device and sends data to a second app (RECEIVER) using Broadcast receiver/intents. The SENDER app runs in the background and the RECEIVER app interacts with the User in the foreground. All worked fine until Android 8.0...