Mic input

[Jim Gettys]

As far as analog input mode is concerned, it isn't implemented in the
driver yet.

Details can be found at:
http://dev.laptop.org/ticket/42

Which captures the information we used to make it work in May/June.

I'm sure Marcelo would be happy to have some help if someone wants to go
complete the driver work.
                                      - Jim


On Wed, 2006-10-11 at 16:24 +0200, Bert Freudenberg wrote:
> Am 11.10.2006 um 15:51 schrieb Jim Gettys:
> 
> > On Wed, 2006-10-11 at 15:13 +0200, Bert Freudenberg wrote:
> >> Hi,
> >>
> >> I connected a headset (analog mic and phones) to an A-test board.
> >> Sound output works fine after "alsaunmute". I have difficulties with
> >> input, though.
> >>
> >> I unmuted "Mic" in alsamixer, and tried arecord. Nothing is recorded.
> >> "V_REFOUT" does make a difference, it connects in and out so I hear
> >> what I'm saying directly (even more so if I enable "Mic boost").
> >> However, in arecord I still get silence.
> >>
> >> So - what do I need to do for mic recording? Does this have to do
> >> with the analog input, do I have to switch that off?
> >
> > Of course you have to switch it off; otherwise we'd have it on all the
> > time and have no control at all.
> 
> That's why I assumed it would be off by default.
> 
> The only documentation I could find is in a mailing list thread  
> (http://mailman.laptop.org/pipermail/devel/2006-July/000672.html):
> 
> 	*a- tell the EC to turn on MIC_AC (ie: bypass C35 and R25) [ OLPC  
> specific ]
> 	*b- tell ALSA to disable VREFOUT and the high pass filter [ AD1888  
> specific ]
> 
> So how do I "tell the EC to turn off MIC_AC"?
> 
> > Whether this is actually your problem, only you can tell.
> 
> Well, is it normal that enabling this loops the mic directly to the  
> phones?
> 
> - Bert -
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-- 
Jim Gettys
One Laptop Per Child