From: Waldemar Neto (wpneto_at_o...)
Date: 2001-05-21 12:32:44
adding Two (improbable and a litle crazy) ideas :
We take for sure the most of soundcard have two unchangeable features ( and ) it must be sure for almost the soundcard models):
1) low pass filter built-in in DSP main chip
2) clock selectable ( 8k,11k,22k and 44 kHsampl )
And :
1) IF one of them will can be changed easily in specific model of soundcard?
( I don't mention the other hi or lo filter selectable by software ) we could cut out the filter doing a shortcut
from input to ouput . ) improbable question , but we should at least think about ...
2) If we find some soundcard with clock programmable in full range ( from1 to x kHz ) and we could set
a very low frequency clock by software ( for example ) less than 1 Khz , eg, 128 Hz (sample/s) than we'd
have shifted the low pass filter for cut in less than 2 Hz ( missing some eeg band yet ).
2b) if we find some soundcard model with clock isolated in the board we could inject another lower frequency ( or divide )
If one think we could have succeed in one of those mad ideas , we'll have to find soundcard circuits details hardly
This is not very acceptable teoretically ( but can work technically ), but instead a despair trial to use soundcard with the least of trouble (:-))
Regards
----- Original Message -----
From: Rob Sacks
To: buildcheapeeg_at_yahoogroups.com
Sent: Monday, May 21, 2001 2:57 AM
Subject: Re: [buildcheapeeg] PC software : Driver
Hi Waldemar,
Oh, if we're talking about some kind of small driver,
I agree that C is okay. I thought we were
talking about the whole PC program.
> will it use an interrupt hook , or RS232 has it "built in"?
I only know the situation with Windows. For an
application, nowadays Microsoft recommends the
use of the "ReadFile" function to read the serial
port. The OS handles all the details and maintains
a buffer.
When an appliction tries to hook an interrupt
in 32-bit Windows it actually hooks only a
software emulation of the interrupt because
Windows virtualizes (hides) the hardware event
from applications.
On the other hand, if you really want to hook the
real hardware interrupt, Windows allows you to do
it by writing the program in a special driver
format that runs at the OS privilege level.
Regards,
Rob
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This archive was generated by hypermail 2.1.4 : 2002-07-27 12:28:30 BST