LP-CC1352P7: CC3200 Audio boost card Microphone amplitude is low

Vinay Kulkarni

Prodigy 140 points

Part Number: LP-CC1352P7
Other Parts Discussed in Thread: CC1352P7, CC3200

Hi ,

We are using launchpad CC1352P7 with CC3200 Audioboost card.

We were able to tap Microphone output in to buffer, but the amplitude is very low.

we made these changes to the I2Secho example code to enable onboard microphone of CC3200.

status = AudioCodec_config(AudioCodec_TI_3254, AudioCodec_16_BIT,
SAMPLE_RATE, AudioCodec_MONO, AudioCodec_SPEAKER_HP,
//AudioCodec_MIC_ALL);
AudioCodec_MIC_ONBOARD);

/* Volume control */
AudioCodec_speakerVolCtrl(AudioCodec_TI_3254, AudioCodec_SPEAKER_HP, 75);
AudioCodec_micVolCtrl(AudioCodec_TI_3254, AudioCodec_MIC_ONBOARD, 100); //AudioCodec_MIC_ONBOARD

#define INPUT_OPTION AudioCodec_MIC_ONBOARD //AudioCodec_MIC_MONO //AudioCodec_MIC_LINE_IN

As you can see we increased the volume to 100%, but even then we are getting low amplitude speech from microphone.

Any suggestion or hints to boost its amplitude. (One option we have is to scale up the amplitude, but it means additional processing, hence avoiding it)

over 1 year ago

0 Arthur R☑️ over 1 year ago

TI__Genius 16316 points

Hi,

Do you notice any difference in volume between, let's say, 75% and 100% volume? By that I mean if you can see a difference in amplitude.

Regards,

Arthur

0 Vinay Kulkarni over 1 year ago in reply to Arthur R☑️

Prodigy 140 points

Yeah Arthur, we can see mild differences between 75% and 100%.
I have not exactly measured differences in maximum amplitudes between the two.

0 Arthur R☑️ over 1 year ago in reply to Vinay Kulkarni

TI__Genius 16316 points

Is there any way you could adjust the ADC gain of the audio codec?

I think you can do so using such a call:

AudioCodec_regWrite(TI3254_ADC_FINE_GAIN_ADJ_REG, 0x00); // Left and Right ADC Channel Un-muted. Left and Right ADC Channel Fine Gain = 0dB,

Refer yourself to the register map in the datasheet to see if there are such options availiable.

Regards,

Arthur

0 Vinay Kulkarni over 1 year ago in reply to Arthur R☑️

Prodigy 140 points

Thanks Arthur.

I changed the setting as per your advice. I can see change (increased) in mic volume now. But still the amplitudes are on lower side.

If i speak loudly then, the amplitudes reach around 0.5.

I understood that Mic mute value is :0x88 and unmute is 0x00, hence i tried 0x44 as well , the middle value. The behavior remained same.

Is this right setting ?, where i can find the right value for ADC setting ?. 0x88 and 0x00 was seen in Audiocodec.c.

Any further pointers to improve the gain ?

+1 Arthur R☑️ over 1 year ago in reply to Vinay Kulkarni

TI__Genius 16316 points

Hi,

In that case, you could try to use the Automatic Gain Control features of the codec, as seen in that application note:

https://www.ti.com/lit/an/slaa446/slaa446.pdf?ts=1657296435430&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTLV320AIC3254

Let me know how it worked for you,

Regards,

Arthur

0 Vinay Kulkarni over 1 year ago in reply to Arthur R☑️

Prodigy 140 points

sorry for late reply.

Thanks Arthur ....i will read and try this. But we can close this issue.

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LP-CC1352P7: CC3200 Audio boost card Microphone amplitude is low