PCM2912A board

sandeep kumar sanku

Prodigy 120 points

Other Parts Discussed in Thread: PCM2912A

Hi Ivan,

Creating a separate thread for this discussion.

Previous thread:

I got the DEM-PCM2912A board. I am trying to use the board with microphone from sound professionals

Microphone link: http://www.soundprofessionals.com/cgi-bin/gold/item/SP-MMM-1

I tried on linux but there was no output from aplay. So I connected in windows and followed the instructions inPCM2912a user manual by changing the settings in control panel. The red light for microphone input will be ON but I am not able to record any audio from the board Mic in. The microphone is working fine when connected to laptop Mic in. So I was wondering if there are any restrictions w.r.to DEM-PCM2912A microphone input.

Please let me know.

Further today I checked the voltage at TP14. I get around ~1.65V. So I was thinking microphone is not getting enough power to capture data. Please confirm if the voltage input for microphone that I am observing is expected one.

Thanks

Sandeep

over 10 years ago

0 Ivan Salazar over 10 years ago

TI__Guru** 114635 points

Hi Sandeep,

I have just replied to the other post.
Let me take a look at the voltage input for microphone at my setup.

Best regards,
-Ivan Salazar
Texas Instruments

0 sandeep kumar sanku over 10 years ago in reply to Ivan Salazar

Prodigy 120 points

Hi Ivan,

I am thinking that power supply is not enough for the particular microphone that I am connecting. Please let me know if the microphone is compatible with PCM2912A board.
Link:
www.soundprofessionals.com/.../SP-MMM-1

Thanks
Sandeep

0 Ivan Salazar over 10 years ago in reply to sandeep kumar sanku

TI__Guru** 114635 points

Sandeep,

Have you tried with a different microphone?
PCM2912A Mic Bias is 0.75Vcca = 0.75*3.3 = 2.475-V; I have measured this voltage at C9 and it is close to 3-V. This is designed to drive electret microphones.
I have measured voltage at TP14 and I get around 2.4-V.

Best regards,
-Ivan Salazar
Texas Instruments

0 sandeep kumar sanku over 10 years ago in reply to Ivan Salazar

Prodigy 120 points

Hi Ivan,

I am getting around 2.55V at C9 and 1.65V at TP14. I tried with headset which has microphone input. It is able to capture the data but with background noise. I am still thinking why the voltages are different in your setup.

Please let me know if TI USB Mic input is compatible the microphone from Sound professionals as I need to use this particular microphone and not sure if it falls under electret microphone range.

www.soundprofessionals.com/.../SP-MMM-1

Thanks
Sandeep

0 sandeep kumar sanku over 10 years ago in reply to sandeep kumar sanku

Prodigy 120 points

Can we use external battery power to power up microphone and give the output of battery to TI Mic input?
www.soundprofessionals.com/.../SP-SPSB-11

Please let me know if I use battery which provides 12v/9v microphone bias and the o/p of battery is given to TI MIc input, will it affect the functionality of chip.
Thanks for the help

Best Regards
Sandeep

0 sandeep kumar sanku over 10 years ago in reply to sandeep kumar sanku

Prodigy 120 points

Hi Ivan,

I got to know from sound professionals that the microphone I am using requires only 2vdc to power up. So they say extern battery power is not required. I am wondering if there is any configuration that needs to be done for PCM2912a chip which can help in powering up, capturing data from microphone to USB card.

Sorry for repeated queries.

Thanks for the help.

Best Regards
Sandeep

0 Ivan Salazar over 10 years ago in reply to sandeep kumar sanku

TI__Guru** 114635 points

Sandeep,

I have corroborated the measured voltage levels with a different multimeter and the voltage levels are closer to yours.
I get 2.55-V at C9 and 1.697-V at TP14.
I think there is no way to modify the power to drive the mic. The only thing that modifies the input mic path is the integrated +20-dB amplifier.

Best regards,
-Ivan Salazar
Texas Instruments

0 sandeep kumar sanku over 10 years ago in reply to Ivan Salazar

Prodigy 120 points

Hi Ivan,

Thanks for the information. I am thinking of changing the microphone so that TI PCM 2912A card can be used because it supports multiple sampling frequencies. I am looking for following things in microphone

1. Omni-directionial

2. Frequency response: ±1 dB: 100 Hz to 8 kHz and ±2 dB: 50 Hz to 20 kHz

Even if it is matches 90% it's fine. Please suggest suitable microphones which can work with TI PCM 2912A card.

Thanks for the help.

Best Regards

Sandeep

0 sandeep kumar sanku over 10 years ago in reply to sandeep kumar sanku

Prodigy 120 points

HI Ivan,

Please let me know if below microphone can work with TI PCM2912a board

http://www.microphonemadness.com/tiny-mono-microphone-omni-directional-frequency-response-20-20-000-hz-mm-tmm-1.html

Mic bias is given as 1.5v-10v. So I assume TI board should power this mic.

Thanks

Sandeep

0 Ivan Salazar over 10 years ago in reply to sandeep kumar sanku

TI__Guru** 114635 points

Sandeep,

As you said, according to mic bias specification, PCM2912A should be able to drive this microphone.

Best regards,
-Ivan Salazar
Texas Instruments

0 sandeep kumar sanku over 10 years ago in reply to Ivan Salazar

Prodigy 120 points

Hi Ivan,

Thanks for the confirmation.

Best Regards,

Sandeep

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PCM2912A board