Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!usc!elroy.jpl.nasa.gov!cit-vax!tybalt.caltech.edu!madler
From: madler@tybalt.caltech.edu (Mark Adler)
Newsgroups: comp.sys.handhelds
Subject: Radio Shack $3.49 Infrared Receiver
Summary: Victory!
Message-ID: <13262@cit-vax.Caltech.Edu>
Date: 14 Jan 90 15:08:02 GMT
References: <1990Jan14.011118.20165@i-core.UUCP>
Sender: news@cit-vax.Caltech.Edu
Reply-To: madler@tybalt.caltech.edu.UUCP (Mark Adler)
Organization: California Institute of Technology
Lines: 23


Well, after messing around with the resistor and getting better, but not
good enough results, it dawned on me how to get around the run-together-
bits problem in software.  I had not previously considered using the
information available about the length of the pulse.  The melded bits
only occur for adjacent half-bit times with pulses, so all I have to do
is decode the run-together-bits for what they are, using the length of
the pulse to figure out how many there are.

I did that.  I now have a program that can download data from an HP-28S
(and presumably any other HP with an IR LED) using an unmodified Radio
Shack GP1U52X Infrared Receiver (catalog number 276-137), available for
a mere $3.49 (plus tax).  I decided to make the program (written in
Turbo C 2.0) shareware, and I am charging a modest $5 for it.  I will
send a separate mail item containing the source to comp.sys.handhelds.
So for less than $10 and little bit of wiring, you can read data from
your HP into your PC.  The details are in the source code.  Have fun.

Mark Adler
madler@hamlet.caltech.edu

The opinions expressed here are not in fact mine, but rather belong to
a small worm that lives on the fourth planet out from Betelgeuse.