TLV320AIC3262: Reduce sensitivity of digital MEMS microphone on GPI1

David-D-Jones

Prodigy 225 points

Part Number: TLV320AIC3262

Hello,

We have a Knowles SPK0415HM4H-B-7 digital MEMS microphone connected to GPI1 on the TLV320AIC3262.

It works, but the microphone is incredibly sensitive.

The microphone has to be held at full arms length otherwise the audio input is too high and is badly distorted.

Is there a fixed registry entry we can use to reduce the digital gain / sensitivity of digital MEMS microphone on GPI1?

Thanks.

over 5 years ago

0 Diego Melendez over 5 years ago

TI__Guru 57800 points

Hi, David,

The digital mic interface of the AIC3262 is tied to the ADC digital section, where the ADC volume control (B0_P0_R83/84) could be used to attenuate the digital mic input signal. If you are using the miniDSP, you can also add volume controls to attenuate the input level.

Best Regards,

-Diego Meléndez López
Audio Applications Engineer

0 David-D-Jones over 5 years ago in reply to Diego Melendez

Prodigy 225 points

Hi Diego,

We have checked our configuration and both B0_P0_R83/84 are set to 68 = -12.0 dB

But the digital microphones on GPI1 & GPI2 are still incredibly sensitive, picking up sounds from neighbouring rooms through the walls.

Is there any other configuration we can apply?

Thanks.

0 Diego Melendez over 5 years ago in reply to David-D-Jones

TI__Guru 57800 points

Hi, David,

Can you please share what are the gains applied in the digital mic signal path apart from register B0_P0_R83/84?, it seems there is a high gain applied somewhere there. If not, It may be necessary to include a volume attenuation section on the miniDSP of the AIC3262 to reduce the mic output amplitude.

Best Regards,

-Diego Meléndez López
Audio Applications Engineer

0 David-D-Jones over 5 years ago in reply to Diego Melendez

Prodigy 225 points

Hello Diego - here are the Dec1xIn_1 settings:

0 David-D-Jones over 5 years ago in reply to David-D-Jones

Prodigy 225 points

Hello Diego Melendez , do you have any further thoughts on this question?

As well as the exceptionally high sensitivity we are also seeing clipping when the user speaks with the microphone close to their mouth.

0 Diego Melendez over 5 years ago in reply to David-D-Jones

TI__Guru 57800 points

Hi, David,

Sorry for the delay, I was traveling a couple weeks back and lost track of this issue. I actually wanted to know the gain settings applied to the DMIC path, not only the decimation filter from PPS. I assume you are using PPS, so it would be useful if you can share the system settings code to verify that no additional gain is being applied to the DMIC signal; the description of the issue suggests that a very high gain is being applied. Also, are you using any AGC, filter or volume control on the miniDSP process flow?.

Best Regards,

-Diego Meléndez López
Audio Applications Engineer

0 David-D-Jones over 5 years ago in reply to Diego Melendez

Prodigy 225 points

Hi Diego, I will send you the files privately. Can you tell me your email address or send me a private message? Thanks.

0 David-D-Jones over 5 years ago in reply to David-D-Jones

Prodigy 225 points

Hello Diego Melendez,

I have just sent you our PPS configuration in a private message.

Hopefully you will find something we have missed in our configuration of the digital MEMS microphone on GPI1.

The audio levels are far too high. Even with AGC we are getting clipping and distortion problems.

Thanks.

0 David-D-Jones over 5 years ago in reply to David-D-Jones

Prodigy 225 points

Our current digital MEMs microphone is Knowles SPH0641LM4H-1. Datasheet: www.mouser.com/.../SPH0641LM4H-1-952032.pdf

0 Diego Melendez over 5 years ago in reply to David-D-Jones

TI__Guru 57800 points

Hi, David,

Thanks for sharing the information, I will take a look and will follow-up with you via private message.

Best Regards,

-Diego Meléndez López
Audio Applications Engineer

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TLV320AIC3262: Reduce sensitivity of digital MEMS microphone on GPI1