geofence

Introduction

This directory provides a flexible geofence implementation that runs on this MCU and can be used with GNSS, cellular or short-range devices.

Usage

The api directory defines the geofence API; a geofence may consist of multiple circles and/or multiple polygons with multiple vertices. The geofence(s) created in this way may be applied using the uGnssGeofence, uCellGeofence or uWifiGeofence APIs such that, whenever a GNSS or CellLocate (cellular) or Google Maps/Skyhook/Here (Wi-Fi) location fix is achieved it is tested against the fence.

This code is only included if U_CFG_GEOFENCE is defined, since maths and floating point operations are required. If you wish to create fences that are larger than 1 km in size then you should employ a true earth model, using WGS84 coordinates: see the instructions at the top of u_geofence_geodesic.h and the note below about GeographicLib for how to do this.

The test directory contains tests that can be run on any platform with the exception of those that generate .kml files for visual inspection, which will only run on Windows.

Sub-module geographiclib

If you do not provide your own geodesic functions and intend to use fences with shapes greater than 1 km in size, where the non-spherical nature of the earth has an impact, GeographicLib should be used. To obtain this as a sub-module, make sure that you have done:

git submodule update --init --recursive

...and:

• when you set the CMake variable UBXLIB_FEATURES in your CMakeLists.txt file, add geodesic to the list of features,
• define the conditional compilation flag U_CFG_GEOFENCE_USE_GEODESIC for your build of ubxlib (this will happen automatically on some platforms but, unfortunately, it does not on ESP-IDF and there is no harm in adding it anyway, to be completely sure),
• pass the CMake variable UBXLIB_EXTRA_LIBS, as set by ubxlib.cmake, to the link stage of your CMakeLists.txt.

Of course, you must also have defined U_CFG_GEOFENCE for your build, in order that geofencing is included at all.