OK, from reading some of the posts it sounds like I may have a bad
serial on my beagleboard, but I thought I'd run it past you to verify
that I am not missing something.
I am running my beagleboard from a 5v power supply. I have the serial
connected to my computer and I get a good display of the booting
process. My issue is that I am unable to issue any commands to the
beagleboard. Anything that I type using HyperTerm or TeraTerm doesn't
show up (it sits at the OMAP3 beagleboard.org # prompt).
So I tried multiple serial cables, multiple computers and multiple
terminal programs all with the same results. To me it seems that the
serial port is bad.
Am I missing something or is it a bad serial port?
OK, from reading some of the posts it sounds like I may have a bad
serial on my beagleboard, but I thought I'd run it past you to verify
that I am not missing something.
I am running my beagleboard from a 5v power supply. I have the serial
connected to my computer and I get a good display of the booting
process. My issue is that I am unable to issue any commands to the
beagleboard. Anything that I type using HyperTerm or TeraTerm doesn't
show up (it sits at the OMAP3 beagleboard.org # prompt).
So I tried multiple serial cables, multiple computers and multiple
terminal programs all with the same results. To me it seems that the
serial port is bad.
Am I missing something or is it a bad serial port?
I did verify the settings in both terminal programs and here is what I
get. After it
completes the boot process I am unable to issue any commands to the
beagleboard.
Here's the is beagleboard boot.
HyperTerm: COM2, 115200, 8 None, 1, None
Texas Instruments X-Loader 1.41
Skipped bad block at 0x100000
Starting OS Bootloader...
I recommend checking the RS-232 input signal at BeagleBoard P9 pin 2
with a digital 'scope or an LED with suitable series resistor (start
with 1K), just to make sure a valid RS-232 bit stream is actually
coming from the PC.
If no RS-232 bit stream, see if RS-232 signal is present at the DB-9.
Check for broken wire in DB9 to IDC cable.
BeagleBoard only implements RS-232 signals RX, TX, and GND. Most PCs
are fine as long as you turn off flow control. However, your PC may
want to see DSR before it transmits to BeagleBoard and needs to have
DTR wrapped back to DSR.
Here's a useful experiment: disconnect BeagleBoard and jumper TX (DB9
pin 3) to RX (pin 2) at the end of your null modem cable. See if your
jumper echoes to your terminal emulator. If not, try jumpering DTR
(pin 4) to DSR (pin 6) and repeat test. You can also jumper RTS (pin
7) to CTS (pin 8) if you don't trust your software to have turned off
flow control.
It does sound like the serial port is bad in one direction I suggest you enter an RMA and return the board for repair. We have had a few boards already with this issue.
It does sound like the serial port is bad in one direction I suggest you
enter an RMA and return the board for repair. We have had a few boards
already with this issue.
Any hint what's the root cause of this issue?
For an experienced developer it could be easier and cheaper if this
could be fixed, e.g. with a soldering iron, instead of sending the
board back, e.g. from Europe.
Just got my beagle board from Digikey.
I have the very same issue as described here:
rs232 working only in one direction (beagle->pc).
I had it working once (pc->beagle). Also a few times I had garbage
characters
while typing. Now I have nothing, even after many power cycles.
Is there a way to avoid a RMA?
Well, if you can replace U9, then you can avoid an RMA. It is very tough to do. Then you will need to burn it in and then it could fial agian. Otherwise, you will need to send it back.
The issue is with U9 going bad. Although, we have received a few boards back with these issues and found they worked fine. So, make sure it is the issue. If you are sure, then request an RMA.
It will take about 5 days to repair, burn in, and to retest the repair.
I had the issue with the receive line not working through U9 so I made
a little hardware fix for it. Basically made a small RS232 > TTL level
shifter using an NPN transistor, diode and resistor. Now works fine.
Has the details, schematics are everywhere for simple transistor based
level shifters so I wont repeat it here, but basically take the RX
from pin 2 of the RS232, and use a transistor to invert and hold the
OMAP RX line low, found at test point TP22. This relied on my faulty
U9 chip holding the OMAP RX line high at 1.8v using it's internal 10k
pullup and not shorting it high (I don't know what other peoples cases
would be, but it's worth checking it out properly).
I did this because my beagleboard was in UK customs for two weeks and
I didn't fancy the prospect of going a few more weeks without a
working board :o)
The other way to avoid an RMA is to make sure you have the right IDC10-to-DB9 adapter and a null modem cable. As mentioned previously, the symptom Olivier is seeing is the same as when you have the wrong adapter/cable combination.
The other way to avoid an RMA is to make sure you have the right
IDC10-to-DB9 adapter and a null modem cable. As mentioned previously,
the symptom Olivier is seeing is the same as when you have the wrong
adapter/cable combination.
As I have found out the hard way there appear to be 2 types of these
IDC to DB9 connectors. One as above which is what you want and the other
where IDC:1 -> DB9:1, IDC:2 -> DB9:6, IDC:3 -> DB9:2, IDC:4 -> DB9:7
etc etc
It might be (without thinking about it too hard ) with a paticular
serial cable the second (wrong) type of connector might give comms in
one direction only...
) with a paticular