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List Archive: gentoo-embedded
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To: gentoo-embedded@g.o
From: Jason <gentoo@...>
Subject: Re: JTAG console wierdness
Date: Sun, 14 Oct 2007 16:01:11 -0400
Mike Frysinger wrote:
> On Thursday 11 October 2007, Jason wrote:
>> I'm having a small issue with a Gateworks GW2348-4 [1] ixp4xx board.  I
>> attached the RXD, TXD, and GND lines from an FTDI USB serial TTL cable
>> to the appropriate JTAG pins (RXD, TXD, GND).
> 
> i'm confused ... JTAG != RS232 ... i dont see how you can hook up a RS232 port 
> to JTAG pins and get a serial console ...

Right.  The FTDI cable is a usb serial device on one side and 3.3v TTL
on the other.  The JTAG port on the GW2348-4 has the JTAG pins as well
as the 3.3v TTL RXD, TXD and GND for a serial console.  I'm still
learning this, so I probably have my verbage screwed up. :-)  But, I did
the same thing on the NSLU2 and it worked flawlessly.

>> I can see the bootup messages in minicom, both RedBoot and Linux.  It
>> dumps me to a command prompt, but that's it.  The errors I see are:
>>
>> 1.) CTRL-C to RedBoot yields periods and doesn't stop the boot process.
>> 2.) what I type echoes back, but hitting Enter goes to the beginning of
>> the line, and doesn't go down a line.
>> 3.) no response to any commands eg 'ls<CR>' does not give me a list of
>> directories...
>> 4.) I do have Local Echo turned off, so I'm reasonably confident that
>> the characters I'm seeing are being seen by the board and echoed back.
>> I tried passing minicom '-7' or '-8' with no improvement.  I did get a
>> chinese character for CTRL-C with '-8' as opposed to a period in RedBoot.
>> 5.) I managed to catch the 2sec window to telnet into redboot and load
>> my own kernel and rootfs to ram, and execute, but I get the exact same
>> effects.
>> 6.) The exact same cable, minicom, kernel, and rootfs (made with
>> crossdev/xmerge/xkmake for the OT! criers :-) ) works fine when booted
>> on an NSLU2...
> 
> so the board never seems to respond and all your output gets echoed back ?  
> sounds like the hardware wiring isnt correct ...
> -mike

That's what I'm leaning towards since I had to build my own connector.
I was hoping that it was maybe a $TERM problem.  On the board TERM=dumb,
on my side, TERM=screen or TERM=xterm.  But that wouldn't explain it
happening in RedBoot.

So what kind of wiring error would cause CTRL-C (0x03) and <CR> 0x0d to
not get passed correctly, but [a-zA-Z0-9] to go through okay?

Jason.
-- 
gentoo-embedded@g.o mailing list


Replies:
Re: JTAG console wierdness
-- Mike Frysinger
References:
JTAG console wierdness
-- Jason
Re: JTAG console wierdness
-- Mike Frysinger
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Updated Jun 17, 2009

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