[Gta04-owner] fm-tuner - was Re: hw routing audio patch removed in 3.7?

Andreas Kemnade andreas at kemnade.info
Mon Jun 10 14:50:40 CEST 2013


On Sat, 2013-06-08 at 19:27 +0200, Christoph Mair wrote: 
> On Sat, Jun 8, 2013 at 6:58 PM, Andreas Kemnade <andreas at kemnade.info> wrote:
> > ok, lets summarize what i have seen.
> > Signals at McBSP1 look fine. I was able to add a sound card to send out
> > data to McBSP1. McBSP1 is master. I was never able to get any data from
> > McBSP1. Since McBSP1 is master, it should always get data, since it
> > generates the clock by itself. When recording data, the clocks are
> > present.
> 
> The frame sync signals are also ok?

If I remember correctly, they were fine.

> 
> > I asked in linux-omap about that, got one hint, but that did not help
> > and also nobody seems to use McBSP1 in master mode.
> 
> I used the McBSP1 in master mode to read data from an analog/digital
> converter. I did not use the sound API but the corresponding McBSP
> functions. I'll  see if I can dig up the code.

That would really be helpful. 

> A few things I can remember: When enabled, the McBSP starts the
> (externally measurable) clocks. To get any useful data you have to
> program the frame sync signals. For my application the OMAP generated
> the TX-Framesync (FSX) and the ADC generated the RX-FS (FSR), but you
> can also set the McBSP to generate both internally. To use this
> feature the pinmux has to be correct, IIRC the FSR needs to be muxed
> as *input* but it will also output the framesync signals at the same
> time. I don't know if the Si4721 requires the FSR or generates its
> own.
> 
Si4721 does not give FSR. At the moment I would be happy if I see any
byte coming out of arecord (even it does not come from si4721). But
arecord enables just the clocks/framesync and nothing arrives, not even
a bunch of zero bytes.  That is so disappointing. If i had at least some
noise coming in with arecord I would be happy.

But anyways, i think it is time to retry all that stuff. I had not
touched it for a long time.

Greetings
Andreas Kemnade




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