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Thanks Steven,<br>
<br>
One more addition is:<br>
<br>
- if I use 'grmon' to connect to the DSU port, then load the same app
with grmon and run,<br>
I can see outputs coming out of the COM1 port. <br>
<br>
- it was when I used the onboard bootrom to load the app to ram, then
jump to it that I didn't<br>
see any outputs on COM1 port. Again, when it's connected to
USB<->serial, the outputs<br>
came out fine, with the same app.<br>
Anything else I need to look? Thanks again.<br>
<br>
-mike-<br>
<br>
<br>
<br>
<br>
Steven Grunza wrote:
<blockquote
cite="mid:A51D8ACD861B7E41BFC7FE5C64BE96480B548795@MTLEXVS01.ulticom.com"
type="cite">
<pre wrap="">My first suggestion would be to use a Voltmeter to measure the Voltage
on the PC's COM1. Assuming a DB9 connection you should see -5V or more
between pins 3 and 5. If you have a DB25 then check between pins 2 and
7.
Back in the old days (before Maxim's MAX232 and similar chips) it wasn't
unusual for a cheap RS-232 interface to "steal" negative Voltage power
from the other end of the connection. This usually worked well unless
the data rate was too high or the other end was also trying to "steal"
negative Voltage power. I know of some Tandy machines that used this
trick.
The USB part probably uses either a Maxim or other vendor's RS-232
interface powered from the 5V available on the USB interface.
That's it for my USD 0.02
</pre>
<blockquote type="cite">
<pre wrap="">-----Original Message-----
From: <a class="moz-txt-link-abbreviated" href="mailto:rtems-users-bounces@rtems.org">rtems-users-bounces@rtems.org</a>
[<a class="moz-txt-link-freetext" href="mailto:rtems-users-bounces@rtems.org">mailto:rtems-users-bounces@rtems.org</a>] On Behalf Of mike
Sent: Monday, February 23, 2009 2:03 PM
To: RTEMS Users
Subject: Weird problem on rs232 vs USB-serial...
Hi all,
We have a Leon2-based board using the RTEMS leon2 BSP. The
host is x86 running CentOS 2.6.
With a simple application that outputs to /dev/console for
stdio (printf):
- with the board connected directly to COM1 of the host, no
output is seen
- with the board connected to a USB<->serial adapter
(Keyspan), outputs and inputs were fine
* This is with the same app initializing the UART to 38400,
8N1, no flow control.
* On the host, we just use 'minicom' set for 38400, 8N1, no
flow control
(/dev/ttyS1 in the 1st case and /dev/ttyUSB0 in the 2nd case)
What could possibly be the cause?
Thanks for any comments/pointers.
-mike-
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</pre>
</blockquote>
<pre wrap=""><!---->
</pre>
</blockquote>
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