[alsa-devel] Using aplay and arecord on an ARM

Paul Kavan pkavan at gmail.com
Wed Jun 20 22:22:53 CEST 2007

> You may need to adjust the RCMR, RFRM, TCMR, TFRM register settings in
> > sound/soc/at91/at91- ssc.c to send the data in the mode that your codec
> > expects.  I have only tested I2S and DSP_A modes with S16_LE data.  It's
> > fairly easy to add new modes.
This is certainly part of the problem. I probed the clocks and the frame
sync lines and they are fine for the most part. However, I can tell from the
output that I need to change the default on TD0 to '1' for starters. I also
think that I need to change the format so that the atmel board reads on the
falling edge after sync. I think it already writes on the rising edge, but
will have to see. Also, the width of the sync is one period of the
bitclock....and I need at least two, so I will need to change that.

Fortunately, I have done a lot of grunt work already in writing my basic ssc
driver for that codec. Now I have to dig into at91-ssc.c to see how to
modify that.

> > pcm.!default {
> >     type hw
> >     card 0
> > }
> > pcm.hw {
> >     type hw
> >     card 0
> >     device 0
> >     subdevice 0
> > }
> > ctl.!default {
> >     type hw
> >     card 0
> > }
> > ctl.hw {
> >     type hw
> >     card 0
> > }
The bare bones conf is not working for me and I am getting:

/usr/share/alsa $ aplay -l
**** List of PLAYBACK Hardware Devices ****
ALSA lib conf.c:3949:(snd_config_expand) Unknown parameters 0
ALSA lib control.c:909:(snd_ctl_open_noupdate) Invalid CTL hw:0
aplay: device_list:213: control open (0): Invalid argument

For whatever reason, the default conf file is letting me use speaker-test,
so I can work on debugging the format for now.  I am using alsa-lib-1.0.14aand
alsa-utils-1.0.14, so I am not sure if that makes a difference. If anyone on
the list has a bare bones conf for a simple pcm codec, I would appreciate
some tips on why this one is not working.

Thanks Frank. I am gonna dig into at91-ssc.c now.

Paul David Kavan
Project Engineer
GRH Electronics, Inc.
pkavan at gmail.com

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