Re: Wake PC on Sound Event
- From: cedars123 <cedars123.3i8zdh@xxxxxxxxxxxxxxxx>
- Date: Sun, 2 Nov 2008 04:16:59 -0600
It sounds like an intriguing idea, but I don't think sound
cards make use of PME. At least, I've never heard of one
doing it.
At one time, we had "Wake On Lan". The computer had a three
pin header, the LAN card had a three pin header, and if you
wanted the LAN card to wake the computer, you used a WOL
cable to join the LAN card to the motherboard. That was one
earlier example of an explicit hardware interface for waking.
In one of the more recent versions of PCI standard, they
decided it would be fun to incorporate that function, into
the PCI slot connector itself. By doing that, the user
no longer needs to find and plug in the cable. Every
PCI slot has the function, and multiple cards can be inserted
into the computer, all of which could have access to the PME
signal.
So, with a modern computer, you can get a LAN card that has
PME on its PCI connector, a motherboard that supports PME,
and then the LAN card wakes the computer.
If you were a designer, and wanted to add that function to a
sound card, it would be a relatively simple matter to trigger on
an audio level, and assert PME. I don't know the entire sequence
of events that follows assertion of PME, so cannot comment in
any further detail there.
'PCI Power Management and Device Drivers'
(http://www.microsoft.com/whdc/archive/PCIpm.mspx)
You could have a look at your computer, and see what other features
would do something equivalent. For example, say you have an RS-232
serial port on the computer. Say one of the pins on the connector
is "RI" or "Ring Indicator". And in the BIOS, you see a setting
called "Wake On Ring". That would monitor the RI pin and look
for a state change.
Purchase an external modem with RS-232 interface. You don't have
to do much with it, except connect it to the phone line, and see
if it'll assert RI for you. If it can, the modem could be used
to wake the computer. Again, I cannot comment on the side effects
f doing this (such as whether the modem will attempt to answer
the phone or not, and what Hayes Command Set function would be
needed to "neuter" the modem). The above Microsoft article
implies that PCI devices are scanned, until the thing with an
asserted PME is found, and then the driver for the device
is informed. In this case, it would be the driver for the
RS232 port, that would be triggered, and I don't know what
happens in response. (I seem to remember, you can make
the serial port refuse to answer on a ring, so maybe you
get awakened, but nothing more has to happen.)
So you'd have two things connected to the phone line. You'd
have your current phone tap, that is delivering an analog
signal to the sound card or equivalent. You would also have
your RS232 modem, using it to monitor the Ring Indicator. To integrate
all of these function properly, there are bound to be important
details I'm missing.
One thing I'd be concerned about, is the sound recording application
and how it works. Say you start a recording in the morning at 8AM.
You hang up the phone. (Something now has to put the computer to
sleep...) Now, what happens to the file that was open when you
did sleep command ? Is the file committed, and a
new file started ? Or is all of the audio recording you ever
did, sitting in a file that has not been committed to the
file system. Now, imagine the power goes off to the computer.
Everything since 8AM could now be lost, of your audio recordings.
There could be 1GB of data written to the disk, but because
the file was not "saved" or closed off, the file is not
considered to be there in the file system.
It is for those reasons, I'm not sure you have everything
you need, to make a fully automated phone recording device.
There might be more highly integrated, dedicated phone
recording devices, that would make the job seamless.
Paul
Thanks for the response.
I have been doing a little research in the meantime and discovered that
Wake on Ring was a feature used back in the modem days and as you
explain that it may be useful for my purposes.
I think that you have identified most of the potential difficulties
with using this system and I am wondering if it may be easier just to
find some way to run my pc on a reduced power state. Although this wont
be as efficient since the PC will still be 'on'.
However this appears to be far from straight forward as well.
My idea would be to create a BIOS profile or a Vista profile where the
GPU was disabled and the CPU underclocked and turn off all non essential
hardware and software and hope that the PC can run in this state without
requiring fans.
The problem is that I am not sure how much hardware and software can be
turned off for the voice recording software still to run.
Also I do not know how to under clock my system, disable the GPU, or
identify and turn off non essential hardware and software.
Ideally I would just download a programme do to this! but none exists
as far as I can see.
I dont have the time or courage to work through the Wake on Ring
solution right now, but I would like to explore the power down option a
little more as I think that this will require less technical know how.
Any help would be much appreciated.
.
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