I want the RAK3172 to be in sleep mode all the time. What can I do to wake up when I enter a certain area?
First of all, how to do detect when entering an area? There are many option such as reading iBeacon (BLE), using GPS, proximity sensor, etc.
Determine the type of trigger you have, than you can, for example, setup a pin interrupt (detect pin state change) or wake up at a fixed interval (e.g. 5 seconds) and read GPS/Sensor value to determine if you enter a certain area.
Basically, how do you want to detect is the 1st question you need to think of.