Integrated the power management and storage, this GPS tracker can be a solution for some IoT projects. absolutely open with eagle design files can modify the files as you like for your own projects.
There is also another version with Arduino Zero. (ATSAMD21G18 )
The latest version of Maduino Zero SIM808 GPS Tracker, V3.5, compares to the previous version, there are the following updates:
1. Power Circuit updated. GPS Tracker can be powered now either by a standard 3.7V Lipo battery, or DC jack, 5~12V(current need to 2A at least).
2. Bluetooth3.0+EDR connection added.
You can check its wiki for more info.