[PlanetCCRMA] Re: [Alsa-user] RME MADI word clock problem

Bill Unruh unruh@physics.ubc.ca
Thu Sep 13 16:50:03 2007

On Thu, 13 Sep 2007, Roman Katzer wrote:

> Hi all,
> I have a Linux system with MADI card (snd-hdspm).  The settings can be
> controlled by using the amixer command-line utility.
> Right now there's no MADI hardware connected, but I want to use the
> word clock output to supply a clock signal to sync my hardware.  For
> this, I set the Sample Clock Source of the MADI card to be "Internal
> 48kHz" - so the MADI is clock master and uses its built-in clock.

No, the sample is undoubtedly the highest frequency square wave the system
is able to put out, namely 24KHz. YOur scope time base is probably wrong.

> However, the word clock output outputs a 25kHz square wave (tested
> with a digital scope), not 48kHz.  Re-requesting the same sample rate
> and clock source doesn't change anything.  If I do go ahead and
> request something above 96kHz the word clock output goes to roughly
> 51kHz and stays there, even when trying to get a lower sample rate

Yes, it is now a 48KHz square wave.

> again.
> Can anyone help?
> Best regards, and thanks in advance!
> Roman
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William G. Unruh   |  Canadian Institute for|     Tel: +1(604)822-3273
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