dlleigh@mit-amt.MEDIA.MIT.EDU (Darren L. Leigh) (05/14/88)
At long last, my heart monitor is running. Thanks to all those who
gave advice and technical info. The ECG waveform does not scroll like
I wanted it to (it wraps around), but it still looks OK.
The hardware consists of four TL064 quad op-amps (you probably only
need three, I was lazy), an LM311 comparator, a 555 timer, an LF398
sample and hold, an AD670 8-bit A/D converter, some precision
resistors, a female DB25 connector (to attach to the serial port),
some connectors for the leads and random caps and resistors. As you
can see, it's not terribly expensive.
The software consists of a five line interrupt routine (in assembler)
and about 350 lines of Lattice C that do all the display work.
I sample the amplified EGC signal 200 times per second with a
resolution of 8 bits. These 8 bits go straight into parallel port's
data lines. The output of the hardware beat detector goes into the
parallel port's SEL line. The 555 timer starts an A/D conversion 200
times per second, and the converter's status signal hands the Amiga an
interrupt (into the FLAG line) when the conversion is done.
I'll want to clean things up before I send out the schematics,
documentation and source code. Right now I have finals to study for
and then I'm heading to the Bay Area for the summer, so don't expect
to see anything before the second week of June.
If you're interested, please don't send inquiries yet. My back mail
may not make the transition smoothly. I'll post an announcement when
things are available.
--------
Darren Leigh dlleigh@media-lab.mit.edu
362 Memorial Dr. mit-amt!dlleigh
Cambridge, MA 02139 Copulation and mirrors are abominable
because they increase the number of men.
-- a Heresiarch of Uqbar