Too Long; Didn't Read
A quick search of “Bluetooth Module” in Mouser provides me the following results. The RN4020 is a 1.8V — 3.6V device, meaning your microcontroller power must be within that range. Microchip developed their own called Microchip Low-energy Data Profile (MLDP) which in a nutshell is a private profile to ease the burden. The command you issue determines if a device becomes a peripheral or a central module. You should have a response from your central device like this: