My goal is to build a bluetooth hands free device, basically a speaker phone, to pair with a mobile phone. I am using the Roving Networks RN-52 Bluetooth Audio module mounted on a breakout board from Sparkfun (product). Connecting a speaker and configuring the device for Hands Free Profile (HFP) has been no problem. However, I am having difficulty connecting a microphone. I have a electret condenser mic and breakout board, also from Sparkfun (product).
The RN-52 has five audio input related pins: Mic_R+, Mic_R-, Mic_L+, Mic_L-, and M_bias. The electric mic has three pins: Audio, Ground and VCC.
I have tried connecting the audio and ground of the mic to both the + and - of left and right mic inputs on the RN-52 with no luck. (VCC is connected to 3.3v).
I am certain that the mic connection is my problem, as the module and speaker work fine for streaming audio over A2DP.
I would sincerely appreciate any help or advice.