[alsa-devel] [QUERY] [AUDIO][OMAP3 EVM] arecord not working on OMAP3 EVM

Koyamangalath, Abhilash abhilash.kv at ti.com
Fri Jan 21 15:00:38 CET 2011

Thanks Peter, 
Your comment helped.

> -----Original Message-----
> From: Peter Ujfalusi [mailto:peter.ujfalusi at nokia.com]
> Sent: Friday, January 21, 2011 1:27 PM
> To: Koyamangalath, Abhilash
> Cc: linux-omap at vger.kernel.org; alsa-devel at vger.kernel.org
> Subject: Re: [QUERY] [AUDIO][OMAP3 EVM] arecord not working on OMAP3 EVM
> On 01/20/11 17:26, ext Koyamangalath, Abhilash wrote:
> > Hi all
> > While testing audio capture (using arecord e,g.),I'm getting only noise
> in the (zeroed out) output buffers on the OMAP3 EVM.
> > I have enabled AUXL and AUXR mic inputs through alsamixer, which
> according to the schematics are connected to the "Audio In"
> > connector on the board, even though the TWL4030 reg list does not allow
> me any ways ( or so I think) to specify mic-bias for
> > these aux inputs.
> Well, it is auxiliary input (line in). You do not need bias for it.
> I do not have access to OMAP3 EVM documentation, but Beagle also have
> AUXL/R as input.
> I guess you need to use correct cable, and correct source for the input
> (stereo jack I suppose).
No need of bias precludes using a MIC, so I tried by connecting a Line-in/out audio cable (a cable with a 3.5 mm audio jack on each end) fed from the PC and it worked, thanks. Originally, I had connected a head-phone mic directly to the audio-in port, which it seems, rather expects a dc-biased and/or a pre-amplified signal.

> > With AUXL and AUXR muted - I get only silence, which seems to make
> sense.
> > Is there any basic startup setting I'm missing, maybe specific to OMAP3
> EVM?
> Beagle?
> > Has anyone seen anything like this before, and could provide pointers?
> My bet goes for the wrong cable/accessory pair.
Bang On.
> --
> Péter
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