Serial Port Rx Works, but Tx doesn't....

GoogleGroups
1

Ok, so I got my Beagle yesterday and I'm now trying to test it. I've
followed the how-to from the manual/wiki and I've got it booting into
the Angstrom distribution just fine... but I can't send the Beagle any
data from my computer. It displays info just fine, but either minicom
or the Beagle is completely ignoring my keystrokes. I've checked the
cables, everything seems to be in order (Computer Tx -> Beagle Tx and
Computer Rx -> Beagle Rx).

Any ideas/suggestions? I was thinking about hooking up an LED to my Tx
line to make sure that it's actually transmitting, but I've got to go
stare at a circuit diagram first to figure out how.

2

sprince587 wrote:

Ok, so I got my Beagle yesterday and I'm now trying to test it. I've
followed the how-to from the manual/wiki and I've got it booting into
the Angstrom distribution just fine... but I can't send the Beagle any
data from my computer. It displays info just fine, but either minicom
or the Beagle is completely ignoring my keystrokes. I've checked the
cables, everything seems to be in order (Computer Tx -> Beagle Tx and
Computer Rx -> Beagle Rx).

flow control: OFF (=none)

3

Yup, both hardware and software flow control are set to none, same
problem.

4

Check the System Reference Manual. There is a section to make sure you have the correct ribbon and serial cable. It takes you through the checkout step by step. This is typically the issue people have with the serial port.

Gerald

5

I've checked the
cables, everything seems to be in order (Computer Tx -> Beagle Tx and
Computer Rx -> Beagle Rx).

Shouldn't that be Computer Tx -> Beagle Rx and Beagle Tx -> Computer Rx?

FWIW, I had an early issue with a USB-serial adapter that did not play well with Vista OR Linux. It would appear to work (LEDs and some data getting back), but would send the transmitted keystrokes to oblivion.

6

Keith Williams wrote:

I've checked the
cables, everything seems to be in order (Computer Tx -> Beagle Tx and
Computer Rx -> Beagle Rx).

Shouldn't that be Computer Tx -> Beagle Rx and Beagle Tx -> Computer Rx?

or straight cable vs null-modem....

7

My understanding of the straight vs null-modem serial cables was that
one of them crosses the Rx/Tx lines (null I believe) and the other
doesn't. Regardless, I've tried it both ways, and doing computer Rx ->
beagle Rx gives me (correct) information on my terminal, but the Tx
connection seems as if it's not working. I double checked my serial
device with another prototyping board I had laying around, and it
seems to be working properly with that. I guess it's not a huge
problem for me to be able to access the boot-loader prompt. I had
originally thought I'd need to be able to access that to be able to
boot into a different kernel/operating system, but I've now got
Xubuntu running on the Beagle and I didn't have to do any
modifications over the serial interface.

That being said, I'm going to continue trying to make it work, I'll
read through the manual again and see if there's anything I've missed,
and I'll probably end up ordering one of those serial cables from
Digikey that are linked from the Beagle website, or find a USB version
of one.

Once I get it going, I'll post back my results/solution....