Read Java code from old Android App

I am building mobile apps for iOS and Android. I have found an old Android app online that is very similar to ours. I need someone to dig into the code to view the request/responses for a couple of different bluetooth calls. 1) Login using a PIN and 2) set a PIN. If you are interested I can send you the apk. I'll need the complete set of characters in the commands (there could be some characters in the beginning and end of the response). I'll also need to know how to read the response. I can share the app if interested. Thanks!