Good question. irDA, which is used for the IR
link on a PC, typically uses a serial port with
a modified signal. If you'd like to know more
about the irDA standard download irPHY 1.4 from
[Link: irda.org]On page 38 (Appendix B.3) you'll see the signals
in picture form. As you can see from that picture
the UART deals with data bits that are sent with
a constant pulse width. Unfortunately the MX-500
uses data bits that are not constant pulse width.
I have identified that a zero is 13.3 micro-secs
(us) wide and a one is 20 us. I had to develop
a receiver and transmitter to decode and encode
these. Not difficult but time consuming.
At first I thought that the MX-500 was using irDA
as it uses a light period of 1.6 us when cloning.
This happens to be exactly the same as a width
that can be used by irDA. See Table 2 on page
8 of the above document. Most remotes use IR
on periods of 25 us or so and all IR detectors
for PCs that I have tried have a filter which
precludes them from being useful at the 1.6 us
pulse width that the MX uses. Fortunately I found
an irDA compatible receiver/transmitter which
works very well.
[Link: jdresearch.com].
Believe me one of the first things I tried with
this was to see if the MX-500 uses irDa. But no
luck.
Getting closer. We are aiming to do some major
testing of the device and PC software this weekend.
I'll get back to you early next week. Thanks for
the answers to my questions and continued support.
Mike
