[alsa-devel] Wandboard Quad - SPDIF issue, no sound

[Michael Howard]

On 25/06/2014 15:16, Michael Howard wrote:
>
> On 25/06/2014 00:49, Sinan Akman wrote:
>>
>>   Hi Mike
>>
>>> I have tried a second receiver and the results are the same, as in, the
>>> wandboard fails, the cubietruck works. I fear that this a design issue
>>> and I'm wasting your time.
>>
>>   There is one another thing. When you run aplay for testing I suggest
>> you define the format and the rate explicitly and don't use plugin
>> as part of your device. It is possible that your default format that
>> your aplay on wandbord picks is not compatible with what your receiver
>> can handle.
>>
>>   Regards
>>
>>   Sinan Akman
>>
>>
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> Hi Sinan,
>
> Well I've tried all the formats and various rates without suceess.
>
> I've determined the capabilities of the Wandboard spdif to be;
>
> alsacap -d hw:0,0
> *** Exploring configuration space of device `hw:0,0' for playback ***
> 2 channels
> Sampling rate 32000..48000 Hz
> Sample formats: S16_LE, S24_LE
>
> as opposed to the Cubietruck (which works - as does Win7);
>
>  alsacap -d hw:1,0
> *** Exploring configuration space of device `hw:1,0' for playback ***
> 1..2 channels
> Sampling rate 8000..192000 Hz
> Sample formats: S16_LE
> Significant bits: 16
>
> The ouputs of speaker test are almost identical;
>
> Wnadboard;
>
> speaker-test -Dsysdefault:CARD=imxspdif -c2
>
> speaker-test 1.0.25
>
> Playback device is sysdefault:CARD=imxspdif
> Stream parameters are 48000Hz, S16_LE, 2 channels
> Using 16 octaves of pink noise
> Rate set to 48000Hz (requested 48000Hz)
> Buffer size range from 64 to 16384
> Period size range from 32 to 8192
> Using max buffer size 16384
> Periods = 4
> was set period_size = 4096
> was set buffer_size = 16384
>
> Cubietruck;
>
> speaker-test -Dsysdefault:CARD=sunxisndspdif -c2
>
> speaker-test 1.0.25
>
> Playback device is sysdefault:CARD=sunxisndspdif
> Stream parameters are 48000Hz, S16_LE, 2 channels
> Using 16 octaves of pink noise
> Rate set to 48000Hz (requested 48000Hz)
> Buffer size range from 4096 to 32768
> Period size range from 1024 to 8192
> Using max buffer size 32768
> Periods = 4
> was set period_size = 8192
> was set buffer_size = 32768
>
> One obvious difference is that the Wandboard uses 'snd-soc-dummy-dai'.
>
> I'll get a scope on the job this evening, is there anything 
> inparticular I should be looking for?
>
> Cheers,
> Mike.
>
I've used a scope on both the CT & WB but it didn't shed any light on 
the matter. Voltages are as advertised (which maybe the problem) and 
there is very little difference between the frequencies of the two 
boards or how the wave looks. Frequencies are approx 1.78MHz for the 
Cubietruck and approx 1.8MHz for the wandboard.

The volatges match the spec sheets, i.e. 5v for the Cubietruck and 3.3v 
for the Wandboard at VCC whether audio is playing or not.

So unless both my receivers have a problem with only 3.3v I'm at a loss. 
I can't find anything on the limited specs for the receivers relating to 
this.

I guess I'll just sideline the Wandboards and use proper kit instead. I 
can still compile on them, until they overheat :)

Cheers,
Mike.

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