Using the timer

Using the timer

[Ilya Dmitrichenko]

Hi,

I would like to utilise the hardware timer which is in the soundcard
in an application.

I suppose that I can somehow set snd-seq-timer to use a particular
device as master
and access that via sequencer API? The particular device that I have
is Hammerfall
HDSP (snd-hdsp).

Cheers,
-- 
Ilya

Re: Using the timer

[Clemens Ladisch]

Ilya Dmitrichenko wrote:
> I would like to utilise the hardware timer which is in the soundcard
> in an application.
> 
> The particular device that I have is Hammerfall
> HDSP (snd-hdsp).

What hardware timer?


Regards,
Clemens

Re: Using the timer

[Clemens Ladisch]

Ilya Dmitrichenko wrote:
> On 21 September 2011 13:54, Clemens Ladisch <clemens@ladisch.de> wrote:
> > What hardware timer?
> 
> I meant the clock of the soundcard.

The HDSP does have a sample clock, but it cannot be used independently
from a running PCM stream.

Using this PCM slave timer in the sequencer is possible, but the period
length is likely to be much larger than the desired sequencer timestamp
granularity.

What exactly do you want to do?


Regards,
Clemens

Re: Using the timer

[Clemens Ladisch]

Ilya Dmitrichenko wrote:
> So you are saying that PCM slave timer can be used in some
> way, but it would be clocked at the sampling rate, right?

We get an interrupt at every period boundary, so the timer would
run at, e.g., one 128th of the sampling rate.

> Hm, so 'snd-seq-timer' is essentially hooked to the host cpu
> clock (be that TSC/RTC/HPET) ?

In the default setting, yes.


Regards,
Clemens