The user the youtube shiitakeo a made some interesting videos , but even without free code
koshi.akutsu to translated:
I have read his blog entry. http://qiita.com/shiitakeo/items/059c11fe7d1e211ebb18
He explain how it works. He also knows "in the current official Pokemon Go app still is not set to work with the bluetooth device",
therefore, create custom android app to link and speak to the Niantic API library.
First of all, He created Android app, but also mentioned he will create iOS app in the future . What custom app does,
connect to the device through BLE. and then send / recieve notification(found pokemon, get pokemon, current ongitude latitude, etc ) from the Pokemon Go Server back and forth.
The main function of the app is following two, it's like intermediary device and the server.