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Helpful ReplyRN52 line-in gain command SL,<32 bit hex value>. Firmware v1.16

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Horse2929
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2015/01/28 16:08:26 (permalink)
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RN52 line-in gain command SL,<32 bit hex value>. Firmware v1.16

Does anyone have information on using the command to set the line in gain, SL,<32 bit hex value>? This command is not listed in the latest Bluetooth Audio Module Command Reference User’s Guide DS50002154A but is listed when the H command (Help) is sent to the RN52. The microphone gain command SM,<32 bit value> is in the format <resresMBMA> where MA is the gain of microphone A and MB is the gain of microphone B, but I don’t believe that SL uses the same format. When I get the default data for the microphone gain, by sending GM, 00000909 is returned, which fits the format described in the Command Reference but when I send GL, 60906090 is returned, so the data format is obviously different. Experimenting has shown me that 6090 is not just the gain for one channel because setting SL to 5080 results in negligible difference to the volume level transmitted by the module but setting SL to 6080 results in a noticeably quieter signal. Can anyone tell me what each bit in the 32 bit hex value used with SL does?
 
Also, I am assuming that line-in or microphone input is selected by setting the gain for the input mode required as I can’t find any other command to select the input type. Can anyone confirm this?
 
Many thanks.
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UFAnders
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Re: RN52 line-in gain command SL,<32 bit hex value>. Firmware v1.16 2015/07/09 20:28:03 (permalink)
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Hi Microchip, can we get a response to this? I, too need to drive the audio input with a line-level signal.
 
=]

--
Anders Nelson
Microchip FAE 2008-2011
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ric
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Re: RN52 line-in gain command SL,<32 bit hex value>. Firmware v1.16 2015/07/09 20:37:11 (permalink) ☄ Helpfulby UFAnders 2015/07/09 21:25:36
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Note, this forum is NOT an official Microchip support channel.
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UFAnders
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Re: RN52 line-in gain command SL,<32 bit hex value>. Firmware v1.16 2015/07/29 09:00:05 (permalink)
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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
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UFAnders
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Re: RN52 line-in gain command SL,<32 bit hex value>. Firmware v1.16 2015/07/29 09:00:37 (permalink)
0
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
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