Re: [beagleboard] Microphone Bias Voltage Level

[ybeagle3]

>From a pin allocation prospectively, allocating the right McASP pins may 
introduce other problems (pin sharing, etc). The ADCs have dedicated analog 
pins to avoid this.

For basic ("telephony quality") audio, the ADCs are quite work able. Things 
you need to consider are -
- Signal conditioning (converting the mV range into a signal that fits 
0-1.8V). Biasing is pretty easy - a cap and a resistor should work with many 
mics.
- Noise filtering.
- Software
- The reference on the BBB is hard wired to 1.8V.

I have gone down this path and have it working with PocketSphinx. Highlights 
of the journey - 
- Opamps or single transistor AMPs do work but there is a lot of tuning needed 
keep a usable signal from the ADC. over a range of distances to the mic 
without having to do a lot of shouting or dealing with clipping.
- Using a single chip AGC/mic preamp does make things a lot easier to tune.
- The ADC is quite noisy.
- The output sample rate is 8KHz. There are different settings that can give 
you 8KHz on the ADC but they have different noise characteristic. The settings 
will have to be tuned to match the signal conditioning circuit. 
- Data output via a simple character driver. Original plan was to get this 
into ALSA but haven't found time for that yet. IIO is nice but that requires 
some kind of userland decoding for pocketsphinx. The character driver outputs 
match the 'file' input format for pocketsphinx.


On Thursday, July 14, 2016 19:16:30 John Syne wrote:
> You would be better off using an audio codec for this purpose.
> Unfortunately, the Audio Cape doesn’t bring out the microphone circuitry,
> but you could use a audio preamp and connect to the audio cape audio input.
> 
> Regards,
> John
> 
> > On Jul 14, 2016, at 3:26 PM, keerthana.manivan...@gmail.com wrote:
> > 
> > 
> > Hi there,
> > 
> > I'm looking to use an electret microphone with a beaglebone black for my
> > project. Can't I directly plug the mic into an analog pin and use the
> > data? Do I need a pre amplifier circuit kind of thing to use the mic with
> > a BBB?
> > 
> > 
> > On Tuesday, March 10, 2015 at 11:49:16 PM UTC-5, sns wrote:
> > Will USB headset with mic work for audio application that records sound
> > and playback on beaglebone with quality?Here is there is no need for
> > separate pre- amplifier or circuit that requires biasing mic voltage?
> > 
> > On Thu, Feb 26, 2015 at 2:53 PM, Zainab S.V  > > wrote: What about using microphone input from a headphone
> > for recording and using the headset for playback? Does it need any extra
> > circuitry?
> > 
> > On Tue, Feb 24, 2015 at 8:22 PM, Fredrik Olofsson  > > wrote: all the usb soundcards i've tried so far can don't
> > need biasing.  just solder an electret mic directly to a minijack and
> > connect it to the input of the usb soundcard.  though note that sound
> > quality varies.  some cards make a lot of noise (one logilink model even
> > was blinking a led when active and that interfered and could be heard in
> > the mic input signal.) terratec aureon dual usb is the best sounding card
> > i've found so far.  though i don't own an audio cape so i can't compare.
> > 
> > If i use usb audio interface instead of the cape, is there a need for
> > biasing ?

-- 
Hunyue Yau
http://www.hy-research.com/

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Re: [beagleboard] Microphone Bias Voltage Level

[John Syne]

Please ensure your replies include beagleboad group e-mail list. 

The standard ADC driver is based on IIO framework and does not use the PRU, 
hence you will find the driver under /drivers/iio/adc/ti_am335x_adc.c. 

The libpruio was developed by jeli.freih...@gmail.com 
 and you should ask him about his library. He 
has excellent documentation here:

http://users.freebasic-portal.de/tjf/Projekte/libpruio/doc/html/ 


The library is based on UIO and the following documentation will help you 
understand the concepts:

https://www.kernel.org/doc/htmldocs/uio-howto/index.html 


Regards,
John




> On Jul 15, 2016, at 11:16 AM, keerthana manivannan 
>  wrote:
> 
> oh ok. so that's where PRUs come into picture here. That's why you wrote the 
> libpruio. ok ok. cool. AWESOME.
> 
> On Fri, Jul 15, 2016 at 12:10 PM, John Syne  > wrote:
> OK, so without using PRU you would read from /dev/iio:device0, but the 
> sampling rate isn’t going to be fast enough for you. You can increase the 
> sampling rate by modifying the ADC dts parameters which you will find in the 
> ADC overlay.
> 
> sudo sh -c "echo ‘BB-ADC' > /sys/devices/platform/bone_capemgr/slots"
> Problem is as you increase the sampling rate, the CPU utilization increases 
> because the driver uses interrupts for each scan cycle. 
> 
> Currently the ADC driver is configured for 16x oversample, Open Delay = 152 
> cycles and Sample Delay = 1 cycles.
> 
> 
>  time in us for processing a single channel, calculated as follows:
> 
>  num cycles = open delay + (sample delay + conv time) * averaging
> 
>  num cycles: 152 + (1 + 13) * 16 = 376
> 
>  clock frequency: 24MHz / 8 = 3MHz
>  clock period: 1 / 3MHz = 333ns
> 
>  processing time: 376 * 333ns = 125us
> 
> Regards,
> John
> 
> 
> 
> 
>> On Jul 15, 2016, at 9:31 AM, keerthana manivannan 
>> > 
>> wrote:
>> 
>> oh. I'm like completely new to this but curious to learn:
>> 
>> 1. I have an electret mic (this one  
>> ) which I'm trying 
>> to get signals from using a beaglebone black. So if I level shift the analog 
>> signal outputs from the mic and read it from ADC pins like 
>> sys/devices/platform/omap/tsc/ain1 (or whatever pin), what will that result 
>> in?
>> 
>> Thanks for responding so quickly. I really really really really appreciate 
>> you taking time to help.
>> 
>> 
>> 
>> On Fri, Jul 15, 2016 at 11:05 AM, John Syne > > wrote:
>> @TJF,
>> 
>> You do realize that audio is more than just an ADC. Think equalization, 
>> dynamic range, etc. Also, you need streaming and that requires a lot more 
>> code on the ARM side which isn’t necessary when you use a CODEC and the ALSA 
>> framework. 
>> 
>> Regards,
>> John
>> 
>> 
>> 
>> 
>>> On Jul 15, 2016, at 7:42 AM, TJF >> > wrote:
>>> 
>>> Hi!
>>> 
>>> Am Freitag, 15. Juli 2016 00:33:44 UTC+2 schrieb keerthana@gmail.com 
>>> :
>>> I'm looking to use an electret microphone with a beaglebone black for my 
>>> project. Can't I directly plug the mic into an analog pin and use the data?
>>> Do I need a pre amplifier circuit kind of thing to use the mic with a BBB?
>>> 
>>> The AIN pins range is 0 to 1V8. You'd need an amplifier to shift the mic 
>>> voltage (by 0V9) and limit the output (to 0V9). But no need for any codec 
>>> nor Audio Cape. For high speed ADC (>4kS/s) use libpruio 
>>> .
>>> 
>>> BR
>>> 
>>> -- 
>>> For more options, visit http://beagleboard.org/discuss 
>>> 
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>> 
>> 
> 
> 

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Re: [beagleboard] Microphone Bias Voltage Level

[John Syne]

OK, so without using PRU you would read from /dev/iio:device0, but the sampling 
rate isn’t going to be fast enough for you. You can increase the sampling rate 
by modifying the ADC dts parameters which you will find in the ADC overlay.

sudo sh -c "echo ‘BB-ADC' > /sys/devices/platform/bone_capemgr/slots"
Problem is as you increase the sampling rate, the CPU utilization increases 
because the driver uses interrupts for each scan cycle. 

Currently the ADC driver is configured for 16x oversample, Open Delay = 152 
cycles and Sample Delay = 1 cycles.


 time in us for processing a single channel, calculated as follows:

 num cycles = open delay + (sample delay + conv time) * averaging

 num cycles: 152 + (1 + 13) * 16 = 376

 clock frequency: 24MHz / 8 = 3MHz
 clock period: 1 / 3MHz = 333ns

 processing time: 376 * 333ns = 125us

Regards,
John




> On Jul 15, 2016, at 9:31 AM, keerthana manivannan 
>  wrote:
> 
> oh. I'm like completely new to this but curious to learn:
> 
> 1. I have an electret mic (this one  
> ) which I'm trying to 
> get signals from using a beaglebone black. So if I level shift the analog 
> signal outputs from the mic and read it from ADC pins like 
> sys/devices/platform/omap/tsc/ain1 (or whatever pin), what will that result 
> in?
> 
> Thanks for responding so quickly. I really really really really appreciate 
> you taking time to help.
> 
> 
> 
> On Fri, Jul 15, 2016 at 11:05 AM, John Syne  > wrote:
> @TJF,
> 
> You do realize that audio is more than just an ADC. Think equalization, 
> dynamic range, etc. Also, you need streaming and that requires a lot more 
> code on the ARM side which isn’t necessary when you use a CODEC and the ALSA 
> framework. 
> 
> Regards,
> John
> 
> 
> 
> 
>> On Jul 15, 2016, at 7:42 AM, TJF > > wrote:
>> 
>> Hi!
>> 
>> Am Freitag, 15. Juli 2016 00:33:44 UTC+2 schrieb keerthana@gmail.com 
>> :
>> I'm looking to use an electret microphone with a beaglebone black for my 
>> project. Can't I directly plug the mic into an analog pin and use the data?
>> Do I need a pre amplifier circuit kind of thing to use the mic with a BBB?
>> 
>> The AIN pins range is 0 to 1V8. You'd need an amplifier to shift the mic 
>> voltage (by 0V9) and limit the output (to 0V9). But no need for any codec 
>> nor Audio Cape. For high speed ADC (>4kS/s) use libpruio 
>> .
>> 
>> BR
>> 
>> -- 
>> For more options, visit http://beagleboard.org/discuss 
>> 
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>>  
>> .
>> For more options, visit https://groups.google.com/d/optout 
>> .
> 
> 

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Re: [beagleboard] Microphone Bias Voltage Level

[John Syne]

@TJF,

You do realize that audio is more than just an ADC. Think equalization, dynamic 
range, etc. Also, you need streaming and that requires a lot more code on the 
ARM side which isn’t necessary when you use a CODEC and the ALSA framework. 

Regards,
John




> On Jul 15, 2016, at 7:42 AM, TJF  wrote:
> 
> Hi!
> 
> Am Freitag, 15. Juli 2016 00:33:44 UTC+2 schrieb keerthana@gmail.com:
> I'm looking to use an electret microphone with a beaglebone black for my 
> project. Can't I directly plug the mic into an analog pin and use the data?
> Do I need a pre amplifier circuit kind of thing to use the mic with a BBB?
> 
> The AIN pins range is 0 to 1V8. You'd need an amplifier to shift the mic 
> voltage (by 0V9) and limit the output (to 0V9). But no need for any codec nor 
> Audio Cape. For high speed ADC (>4kS/s) use libpruio 
> .
> 
> BR
> 
> -- 
> For more options, visit http://beagleboard.org/discuss 
> 
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Re: [beagleboard] Microphone Bias Voltage Level

[TJF]

Hi!

Am Freitag, 15. Juli 2016 00:33:44 UTC+2 schrieb keerthana@gmail.com:
>
> I'm looking to use an electret microphone with a beaglebone black for my 
> project. Can't I directly plug the mic into an analog pin and use the data?
> Do I need a pre amplifier circuit kind of thing to use the mic with a BBB?
>

The AIN pins range is 0 to 1V8. You'd need an amplifier to shift the mic 
voltage (by 0V9) and limit the output (to 0V9). But no need for any codec 
nor Audio Cape. For high speed ADC (>4kS/s) use libpruio 
.

BR

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Re: [beagleboard] Microphone Bias Voltage Level

[John Syne]

You would be better off using an audio codec for this purpose. Unfortunately, 
the Audio Cape doesn’t bring out the microphone circuitry, but you could use a 
audio preamp and connect to the audio cape audio input. 

Regards,
John




> On Jul 14, 2016, at 3:26 PM, keerthana.manivan...@gmail.com wrote:
> 
> 
> Hi there, 
> 
> I'm looking to use an electret microphone with a beaglebone black for my 
> project. Can't I directly plug the mic into an analog pin and use the data?
> Do I need a pre amplifier circuit kind of thing to use the mic with a BBB?
> 
> 
> On Tuesday, March 10, 2015 at 11:49:16 PM UTC-5, sns wrote:
> Will USB headset with mic work for audio application that records sound and 
> playback on beaglebone with quality?Here is there is no need for separate 
> pre- amplifier or circuit that requires biasing mic voltage?
> 
> On Thu, Feb 26, 2015 at 2:53 PM, Zainab S.V  
> wrote:
> What about using microphone input from a headphone for recording and using 
> the headset for playback? Does it need any extra circuitry?
> 
> On Tue, Feb 24, 2015 at 8:22 PM, Fredrik Olofsson  > wrote:
> all the usb soundcards i've tried so far can don't need biasing.  just solder 
> an electret mic directly to a minijack and connect it to the input of the usb 
> soundcard.  though note that sound quality varies.  some cards make a lot of 
> noise (one logilink model even was blinking a led when active and that 
> interfered and could be heard in the mic input signal.)
> terratec aureon dual usb is the best sounding card i've found so far.  though 
> i don't own an audio cape so i can't compare.
> 
> If i use usb audio interface instead of the cape, is there a need for biasing 
> ?
> 
> 
> -- 
> For more options, visit http://beagleboard.org/discuss 
> 
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> 
> 
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Re: [beagleboard] Microphone Bias Voltage Level

[keerthana . manivannan]

Hi there, 

I'm looking to use an electret microphone with a beaglebone black for my 
project. Can't I directly plug the mic into an analog pin and use the data?
Do I need a pre amplifier circuit kind of thing to use the mic with a BBB?


On Tuesday, March 10, 2015 at 11:49:16 PM UTC-5, sns wrote:
>
> Will USB headset with mic work for audio application that records sound 
> and playback on beaglebone with quality?Here is there is no need for 
> separate pre- amplifier or circuit that requires biasing mic voltage?
>
> On Thu, Feb 26, 2015 at 2:53 PM, Zainab S.V  > wrote:
>
>> What about using microphone input from a headphone for recording and 
>> using the headset for playback? Does it need any extra circuitry?
>>
>> On Tue, Feb 24, 2015 at 8:22 PM, Fredrik Olofsson > > wrote:
>>
>>> all the usb soundcards i've tried so far can don't need biasing.  just 
>>> solder an electret mic directly to a minijack and connect it to the input 
>>> of the usb soundcard.  though note that sound quality varies.  some cards 
>>> make a lot of noise (one logilink model even was blinking a led when active 
>>> and that interfered and could be heard in the mic input signal.)
>>> terratec aureon dual usb is the best sounding card i've found so far. 
>>>  though i don't own an audio cape so i can't compare.
>>>
>>> If i use usb audio interface instead of the cape, is there a need for 
>>> biasing ?
>>>

> -- 
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>>
>>
>

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Re: [beagleboard] Microphone Bias Voltage Level

[Zainab S.V]

Will USB headset with mic work for audio application that records sound and
playback on beaglebone with quality?Here is there is no need for separate
pre- amplifier or circuit that requires biasing mic voltage?

On Thu, Feb 26, 2015 at 2:53 PM, Zainab S.V sv.zai...@gmail.com wrote:

 What about using microphone input from a headphone for recording and using
 the headset for playback? Does it need any extra circuitry?

 On Tue, Feb 24, 2015 at 8:22 PM, Fredrik Olofsson redf...@gmail.com
 wrote:

 all the usb soundcards i've tried so far can don't need biasing.  just
 solder an electret mic directly to a minijack and connect it to the input
 of the usb soundcard.  though note that sound quality varies.  some cards
 make a lot of noise (one logilink model even was blinking a led when active
 and that interfered and could be heard in the mic input signal.)
 terratec aureon dual usb is the best sounding card i've found so far.
  though i don't own an audio cape so i can't compare.

 If i use usb audio interface instead of the cape, is there a need for
 biasing ?


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Re: [beagleboard] Microphone Bias Voltage Level

[Zainab S.V]

What about using microphone input from a headphone for recording and using
the headset for playback? Does it need any extra circuitry?

On Tue, Feb 24, 2015 at 8:22 PM, Fredrik Olofsson redf...@gmail.com wrote:

 all the usb soundcards i've tried so far can don't need biasing.  just
 solder an electret mic directly to a minijack and connect it to the input
 of the usb soundcard.  though note that sound quality varies.  some cards
 make a lot of noise (one logilink model even was blinking a led when active
 and that interfered and could be heard in the mic input signal.)
 terratec aureon dual usb is the best sounding card i've found so far.
  though i don't own an audio cape so i can't compare.

 If i use usb audio interface instead of the cape, is there a need for
 biasing ?


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Re: [beagleboard] Microphone Bias Voltage Level

[Fredrik Olofsson]

all the usb soundcards i've tried so far can don't need biasing.  just 
solder an electret mic directly to a minijack and connect it to the input 
of the usb soundcard.  though note that sound quality varies.  some cards 
make a lot of noise (one logilink model even was blinking a led when active 
and that interfered and could be heard in the mic input signal.)
terratec aureon dual usb is the best sounding card i've found so far. 
 though i don't own an audio cape so i can't compare.

If i use usb audio interface instead of the cape, is there a need for 
biasing ?




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Re: [beagleboard] Microphone Bias Voltage Level

[John Syne]

 On Feb 19, 2015, at 9:11 PM, sns sv.zai...@gmail.com wrote:
 
 Did it work? Can you please say the procedure? I am working on a project that 
 has a similar requirement.
The mic bias voltage on the TLV320AIC3104 isn’t connected on the audio cape so 
you will need external circuitry to use a mic.

Regards,
John
 
 On Tuesday, June 3, 2014 at 9:44:27 PM UTC+5:30, Tristan Phillips wrote:
 
 Hi,
 
 I'm wondering how I can set the mic bias voltage level on the Audio Cape, it 
 is currently off and I cannot get my mic to work.  Can I do this via alsa or 
 something similar?
 
 Thank you,
 
 Tris
 
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Re: [beagleboard] Microphone Bias Voltage Level

[sns]

If i use usb audio interface instead of the cape, is there a need for 
biasing ?
On Friday, February 20, 2015 at 10:57:59 AM UTC+5:30, john3909 wrote:


 On Feb 19, 2015, at 9:11 PM, sns sv.z...@gmail.com javascript: wrote:

 Did it work? Can you please say the procedure? I am working on a project 
 that has a similar requirement.

 The mic bias voltage on the TLV320AIC3104 isn’t connected on the audio 
 cape so you will need external circuitry to use a mic.

 Regards,
 John


 On Tuesday, June 3, 2014 at 9:44:27 PM UTC+5:30, Tristan Phillips wrote:


 Hi,

 I'm wondering how I can set the mic bias voltage level on the Audio Cape, 
 it is currently off and I cannot get my mic to work.  Can I do this via 
 alsa or something similar?

 Thank you,

 Tris


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Re: [beagleboard] Microphone Bias Voltage Level

[Tristan Phillips]

Is there a dummies guide to replacing a kernel on a BBB built with a 
flasher with a new one?

On Tuesday, 3 June 2014 17:58:20 UTC+1, lisarden wrote:

 I think you just need to recompile the kernel with the code provided. Then 
 you use alsamixer to tell which device captures sounds


 2014-06-03 20:51 GMT+04:00 Tristan Phillips tris.p...@gmail.com 
 javascript::

 Thank you, does that mean I need a device tree overlay that tells the 
 driver I'm using a mic as well as line in?

 Will I need to recompile the kernel to apply this patch?


 On Tuesday, 3 June 2014 17:48:15 UTC+1, lisarden wrote:

 Hi!

 diff --git a/sound/soc/davinci/davinci-evm.c 
 b/sound/soc/davinci/davinci-evm.c
 index 7ad7b37..e196aa5 100644
 --- a/sound/soc/davinci/davinci-evm.c
 +++ b/sound/soc/davinci/davinci-evm.c
 @@ -117,15 +117,13 @@ static const struct snd_soc_dapm_route audio_map[] = {
 {Line Out, NULL, RLOUT},
  
 /* Mic connected to (MIC3L | MIC3R) */
 -   {MIC3L, NULL, Mic Bias 2V},
 -   {MIC3R, NULL, Mic Bias 2V},
 -   {Mic Bias 2V, NULL, Mic Jack},
 +   {LINE2L, NULL, Mic Bias 2.5V},
 +   {LINE2R, NULL, Mic Bias 2.5V},
 +   {Mic Bias 2.5V, NULL, Mic Jack},
  
 /* Line In connected to (LINE1L | LINE2L), (LINE1R | LINE2R) */
 {LINE1L, NULL, Line In},
 -   {LINE2L, NULL, Line In},
 {LINE1R, NULL, Line In},
 -   {LINE2R, NULL, Line In},
  };




 2014-06-03 20:14 GMT+04:00 Tristan Phillips tris.p...@gmail.com:


 Hi,

 I'm wondering how I can set the mic bias voltage level on the Audio 
 Cape, it is currently off and I cannot get my mic to work.  Can I do this 
 via alsa or something similar?

 Thank you,

 Tris

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Re: [beagleboard] Microphone Bias Voltage Level

[Maxim Podbereznyy]

sure!
http://eewiki.net/display/linuxonarm/BeagleBone+Black



2014-06-04 21:04 GMT+04:00 Tristan Phillips tris.phill...@gmail.com:

 Is there a dummies guide to replacing a kernel on a BBB built with a
 flasher with a new one?


 On Tuesday, 3 June 2014 17:58:20 UTC+1, lisarden wrote:

 I think you just need to recompile the kernel with the code provided.
 Then you use alsamixer to tell which device captures sounds


 2014-06-03 20:51 GMT+04:00 Tristan Phillips tris.p...@gmail.com:

 Thank you, does that mean I need a device tree overlay that tells the
 driver I'm using a mic as well as line in?

 Will I need to recompile the kernel to apply this patch?


 On Tuesday, 3 June 2014 17:48:15 UTC+1, lisarden wrote:

 Hi!

 diff --git a/sound/soc/davinci/davinci-evm.c 
 b/sound/soc/davinci/davinci-evm.c
 index 7ad7b37..e196aa5 100644
 --- a/sound/soc/davinci/davinci-evm.c
 +++ b/sound/soc/davinci/davinci-evm.c
 @@ -117,15 +117,13 @@ static const struct snd_soc_dapm_route audio_map[] = 
 {
{Line Out, NULL, RLOUT},

/* Mic connected to (MIC3L | MIC3R) */
 -  {MIC3L, NULL, Mic Bias 2V},
 -  {MIC3R, NULL, Mic Bias 2V},
 -  {Mic Bias 2V, NULL, Mic Jack},
 +  {LINE2L, NULL, Mic Bias 2.5V},
 +  {LINE2R, NULL, Mic Bias 2.5V},
 +  {Mic Bias 2.5V, NULL, Mic Jack},

/* Line In connected to (LINE1L | LINE2L), (LINE1R | LINE2R) */
{LINE1L, NULL, Line In},
 -  {LINE2L, NULL, Line In},
{LINE1R, NULL, Line In},
 -  {LINE2R, NULL, Line In},
  };




 2014-06-03 20:14 GMT+04:00 Tristan Phillips tris.p...@gmail.com:


 Hi,

 I'm wondering how I can set the mic bias voltage level on the Audio
 Cape, it is currently off and I cannot get my mic to work.  Can I do this
 via alsa or something similar?

 Thank you,

 Tris

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Re: [beagleboard] Microphone Bias Voltage Level

[Maxim Podbereznyy]

Hi!

diff --git a/sound/soc/davinci/davinci-evm.c b/sound/soc/davinci/davinci-evm.c
index 7ad7b37..e196aa5 100644
--- a/sound/soc/davinci/davinci-evm.c
+++ b/sound/soc/davinci/davinci-evm.c
@@ -117,15 +117,13 @@ static const struct snd_soc_dapm_route audio_map[] = {
{Line Out, NULL, RLOUT},

/* Mic connected to (MIC3L | MIC3R) */
-   {MIC3L, NULL, Mic Bias 2V},
-   {MIC3R, NULL, Mic Bias 2V},
-   {Mic Bias 2V, NULL, Mic Jack},
+   {LINE2L, NULL, Mic Bias 2.5V},
+   {LINE2R, NULL, Mic Bias 2.5V},
+   {Mic Bias 2.5V, NULL, Mic Jack},

/* Line In connected to (LINE1L | LINE2L), (LINE1R | LINE2R) */
{LINE1L, NULL, Line In},
-   {LINE2L, NULL, Line In},
{LINE1R, NULL, Line In},
-   {LINE2R, NULL, Line In},
 };




2014-06-03 20:14 GMT+04:00 Tristan Phillips tris.phill...@gmail.com:


 Hi,

 I'm wondering how I can set the mic bias voltage level on the Audio Cape,
 it is currently off and I cannot get my mic to work.  Can I do this via
 alsa or something similar?

 Thank you,

 Tris

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Re: [beagleboard] Microphone Bias Voltage Level

[Tristan Phillips]

Thank you, does that mean I need a device tree overlay that tells the 
driver I'm using a mic as well as line in?

Will I need to recompile the kernel to apply this patch?

On Tuesday, 3 June 2014 17:48:15 UTC+1, lisarden wrote:

 Hi!

 diff --git a/sound/soc/davinci/davinci-evm.c b/sound/soc/davinci/davinci-evm.c
 index 7ad7b37..e196aa5 100644
 --- a/sound/soc/davinci/davinci-evm.c
 +++ b/sound/soc/davinci/davinci-evm.c
 @@ -117,15 +117,13 @@ static const struct snd_soc_dapm_route audio_map[] = {
   {Line Out, NULL, RLOUT},
  
   /* Mic connected to (MIC3L | MIC3R) */
 - {MIC3L, NULL, Mic Bias 2V},
 - {MIC3R, NULL, Mic Bias 2V},
 - {Mic Bias 2V, NULL, Mic Jack},
 + {LINE2L, NULL, Mic Bias 2.5V},
 + {LINE2R, NULL, Mic Bias 2.5V},
 + {Mic Bias 2.5V, NULL, Mic Jack},
  
   /* Line In connected to (LINE1L | LINE2L), (LINE1R | LINE2R) */
   {LINE1L, NULL, Line In},
 - {LINE2L, NULL, Line In},
   {LINE1R, NULL, Line In},
 - {LINE2R, NULL, Line In},
  };




 2014-06-03 20:14 GMT+04:00 Tristan Phillips tris.p...@gmail.com 
 javascript::


 Hi,

 I'm wondering how I can set the mic bias voltage level on the Audio Cape, 
 it is currently off and I cannot get my mic to work.  Can I do this via 
 alsa or something similar?

 Thank you,

 Tris

 -- 
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 --- 
 You received this message because you are subscribed to the Google Groups 
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 Company - http://www.linkedin.com/company/mentorel
 Facebook - https://www.facebook.com/mentorel.company
  

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Re: [beagleboard] Microphone Bias Voltage Level

[Maxim Podbereznyy]

I think you just need to recompile the kernel with the code provided. Then
you use alsamixer to tell which device captures sounds


2014-06-03 20:51 GMT+04:00 Tristan Phillips tris.phill...@gmail.com:

 Thank you, does that mean I need a device tree overlay that tells the
 driver I'm using a mic as well as line in?

 Will I need to recompile the kernel to apply this patch?


 On Tuesday, 3 June 2014 17:48:15 UTC+1, lisarden wrote:

 Hi!

 diff --git a/sound/soc/davinci/davinci-evm.c 
 b/sound/soc/davinci/davinci-evm.c
 index 7ad7b37..e196aa5 100644
 --- a/sound/soc/davinci/davinci-evm.c
 +++ b/sound/soc/davinci/davinci-evm.c
 @@ -117,15 +117,13 @@ static const struct snd_soc_dapm_route audio_map[] = {
  {Line Out, NULL, RLOUT},

  /* Mic connected to (MIC3L | MIC3R) */
 -{MIC3L, NULL, Mic Bias 2V},
 -{MIC3R, NULL, Mic Bias 2V},
 -{Mic Bias 2V, NULL, Mic Jack},
 +{LINE2L, NULL, Mic Bias 2.5V},
 +{LINE2R, NULL, Mic Bias 2.5V},
 +{Mic Bias 2.5V, NULL, Mic Jack},

  /* Line In connected to (LINE1L | LINE2L), (LINE1R | LINE2R) */
  {LINE1L, NULL, Line In},
 -{LINE2L, NULL, Line In},
  {LINE1R, NULL, Line In},
 -{LINE2R, NULL, Line In},
  };




 2014-06-03 20:14 GMT+04:00 Tristan Phillips tris.p...@gmail.com:


 Hi,

 I'm wondering how I can set the mic bias voltage level on the Audio
 Cape, it is currently off and I cannot get my mic to work.  Can I do this
 via alsa or something similar?

 Thank you,

 Tris

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