RN52 Line/Mic input selection

Author
FabioC
New Member
  • Total Posts : 2
  • Reward points : 0
  • Joined: 2014/01/03 10:30:30
  • Location: 0
  • Status: offline
2014/01/03 10:36:17 (permalink)

RN52 Line/Mic input selection

Hello,
could anyone provide me more detailed information on how to use audio line level instead of microphone signals on the mic pins on the RN52 module.
From the DS it looks that there is a selectable preamplifier gain that can be set to 0dB with audio line level inputs.
Thanks!
Fabio
#1

4 Replies Related Threads

    UFAnders
    New Member
    • Total Posts : 11
    • Reward points : 0
    • Joined: 2010/05/28 10:28:11
    • Location: San Francisco
    • Status: offline
    Re: RN52 Line/Mic input selection 2015/07/09 20:26:12 (permalink)
    Hi, has anyone responded to this? I have the same question!

    --
    Anders Nelson
    Microchip FAE 2008-2011
    #2
    UFAnders
    New Member
    • Total Posts : 11
    • Reward points : 0
    • Joined: 2010/05/28 10:28:11
    • Location: San Francisco
    • Status: offline
    Re: RN52 Line/Mic input selection 2015/07/29 08:56:06 (permalink)
    It appears MCHP does not monitor this forum, so here are the answers I got by pulling my ex-employee strings. Even this took about 10 days while a support ticket response took 20, and STILL didn't answer my ticket usefully. Anyway, the answer:
    1. How do I bypass the microphone gain stage to use the RN-52 with a pre-biased (1/2 of 3.3v), line-level audio input signal? This is referenced in the usage guide and datasheet but there is no command documented to use this. Does my application require a CODEC? I sure hope not.

      >>> The microphone gain can be changed from -3dB to 42dB in linear steps. If the gain is set to less than 24dB using the ‘SM’ command the line in mode is automatically entered.
  • Is the audio output intrinsically a line-level signal?

    >>> The audio output is a speaker level signal and not line level signal.
  • Which input channel (left or right) is used when in HFP mode? I'm making a device to turn a standard telephone into a bluetooth handset by way of a SLIC.

    >>> MIC_L+/- is used for HFP mode.
  • Is this a typo? Do they mean the "microphone gain level" can be set from 00 to 1F?

    >>>Yes that is correct. It is a typo. Should be ‘microphone gain level’. I will save this as an update to be captured for document revision. 
  • If the -3 to +42dB gain (45dB range) is entered from 0x00 to 0x1F, that means each increment equals a +1.4dB change. This means the default setting of 0x09 = +9.6dB gain. Is this correct? 

    >>>Yes it is a linear increment and should be an increment of 1.4dB per step. Did SM command work for your design line level input needs?
    To make the speaker outputs work at line-level, see this circuit and accompanying website:
     
     
    Credit: 

  • --
    Anders Nelson
    Microchip FAE 2008-2011
    #3
    radiofm
    Starting Member
    • Total Posts : 59
    • Reward points : 0
    • Joined: 2008/10/23 06:09:19
    • Location: Poznan / Poland
    • Status: offline
    Re: RN52 Line/Mic input selection 2016/07/10 04:03:55 (permalink)
    Hello
    i working at device based on RN52 - it must send audio via bluetooth to for example phone
    i am using audio output from other device (fm receiver)
    question - 
    if i want to use audio inputs in RN52:
    out L (from device) to MIC L+ out R(from device) to MIC R+, MIC L- and MIC R- to GND, MIC BIAS not connected ?
    and - RN52 can send audio and in the same time data to phone via bluetooth ?
     
    Robert
    #4
    radiofm
    Starting Member
    • Total Posts : 59
    • Reward points : 0
    • Joined: 2008/10/23 06:09:19
    • Location: Poznan / Poland
    • Status: offline
    Re: RN52 Line/Mic input selection 2016/07/10 04:04:17 (permalink)
    //double post pls delete.
    post edited by radiofm - 2016/07/10 04:08:41
    #5
    Jump to:
    © 2017 APG vNext Commercial Version 4.5