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Robin Gilks wrote:
<blockquote
cite="mid35194.192.168.1.15.1163845998.squirrel@gilks.ath.cx"
type="cite">
<pre wrap="">[snip]
</pre>
<blockquote type="cite">
<pre wrap="">I found that instead of using pin 4
(DTR) as the transmit pin, it is actually pin 7 (RTS) that is toggling.
When measured against pin 5 (SG), it displays a negative voltage.
(Approaximately -11V). I put Andy's change_chan.sh script in a loop to
keep the channels changing and measured the pin voltages. Pin 7's
voltage starts fluctuating. On my digital meter, it looks like it jumps
between about -9.5V and -11V. As soon as I stop, it returns to a
steady -11V. I'm quite sure this is the pin that is being controlled.
I am attempting to drive the pin using the DirecTV codes from
<a class="moz-txt-link-freetext" href="http://lirc.sourceforge.net/remotes/directv/G051204">http://lirc.sourceforge.net/remotes/directv/G051204</a> in my LIRC file in
place of Andy's Motorola box codes. I'm fairly certain the
configuration is correct. It almost appears as if the lirc_serial
control is driving the incorrect pin, but I have no idea why that would
be.
</pre>
</blockquote>
<pre wrap=""><!---->
If the IR blaster were being driven by pin 7 then that pin would be going
from -11 to +11 - RS232 voltage swings are symmetric (within the bounds of
circuit loading) about zero.
I think what you are seeing is the voltage changing slightly because
another port or pin is taking current and making the RTS pin you have been
monitoring bob up & down a bit.
Things to check:
1. Is pin 4 doing anything
2. Is pin 4 of another port doing something
3. Are there any indications in the log of a failure to load the serial
driver for lirc (perhaps due to the internal driver not being turned off
by setserial).
Its not a mother board that has the 1st serial port reserved for some
internal port, modem, mouse or something like that?
Hopefully this will give you some clues...
</pre>
</blockquote>
<br>
Hi Robin,<br>
<br>
Thanks for your suggestions. A little further thinking about it and a
helpful stumble across this page
(<a class="moz-txt-link-freetext" href="http://www.frontx.com/pro/cpx102_2.html">http://www.frontx.com/pro/cpx102_2.html</a>) has given me the answer.
Apparently, ASUS does not use standard 2x5 serial port wiring on their
motherboards. I had been assuming the pin layout was this:<br>
<br>
1 6<br>
2 7<br>
3 8<br>
4 9<br>
5 10<br>
<br>
<br>
Apparently though (and this is documented NOWHERE I could find at ASUS,
my motherboard docs, etc), ASUS uses the following Intel-motherboard
style of wiring:<br>
<br>
1 2<br>
3 4<br>
5 6<br>
7 8<br>
9 10<br>
<br>
So this would explain the pin 7 vs pin 4 confusion. Guess I was
measuring the voltage between pins 9 and 4 instead of 5 and 7 like I
thought I was. <br>
<br>
After finding the first page, I found a nice site on Intel's
motherboards which documents this nicely:<br>
<br>
<a class="moz-txt-link-freetext" href="http://support.intel.com/support/motherboards/desktop/d845wn/sb/cs-008931.htm">http://support.intel.com/support/motherboards/desktop/d845wn/sb/cs-008931.htm</a><br>
<br>
<br>
Should others have this issue, know that a standard serial port bracket
will not work on your computer. You need an "Intel-style" serial port
bracket. Here's one source: <br>
<br>
<a class="moz-txt-link-freetext" href="http://www.cablestogo.com/product.asp?cat%5Fid=908&sku=28300">http://www.cablestogo.com/product.asp?cat%5Fid=908&sku=28300</a><br>
<br>
<br>
This is a "straight through" wiring. (The first 5 ribbon cable wires
are wired to pins 1-5 directly.) The "standard" is here: <br>
<br>
<a class="moz-txt-link-freetext" href="http://www.cablestogo.com/product.asp?cat%5Fid=908&sku=09480">http://www.cablestogo.com/product.asp?cat%5Fid=908&sku=09480</a><br>
<br>
Note the "crossed configuration" notice, which means the wires at the
DB9 connector alternate between rows. (First line to pin 1, second to
pin 6.) <br>
<br>
Since I had bought a couple of the crossed configuration ones thinking
I *had* accidentally bought an Intel-style bracket, I've now borrowed a
friend's soldering iron and will give a go at the new wiring. I'm
fairly certain at this point this is what has caused me all the
confusion.<br>
<br>
I *had* to assume with 30 years of computer experience, it wasn't
*that* hard to drive an LED from a serial port! :-) As usual, long
hours of frustration tracked down to a rather trivial cause. Really
surprised ASUS doesn't document this better. The motherboard manual
simple says, "Serial bracket available separately", but that's it.
Nothing on their website either. They must assume everyone is using
USB at this point.<br>
<br>
I'll reply to this again once I have the port rewired and can
(hopefully) confirm some success. Hope this helps someone else who
might have hit this as well.<br>
<br>
-- Jay<br>
<br>
<br>
<br>
<BR>
<BR>
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