20060815

Thecus N4100

spent much of yesterday trying to break into the Thecus N4100 that we have at work. I thought it would be a relatively easy thing to try. After all, OpenBSD supports the N2100 and how different can this one be? thought it might be nice to add FreeBSD support to the thing.

Turns out, quite a lot.

I was greeted with gibberish over the serial console port. 115200 looks like the correct baud rate, at least based on looking at the characters with a scope. The bit widths are right, etc. Yet all I get is garbage.

Then I went and googled for others that have done this. While $600 for the empty unit is a bunch of money, it isn't that much in the grand scheme of things. I was surprised to find that no one has a web page about this that google can get to. Maybe I need to learn to search better? Or maybe there's limited searching options for this community.

I've tried jumpers on all the things that looked like jumpers. I've tried every combination possible, but still no joy on the serial port.

The unit works, and is running Thecus' software. The GPL files showed no signs of what the key might be to the serial communications. The settings were 115200, 8, N. Maybe those settings are dependent on a clock that's off by more than a few percent, which is why the serial ports I've tried can't lock to it. I'll have to give the embedded ATMEL part that I'm using a spin to see if I can vary the baud rate enough to see it (the embedded part I use has a base xtal that all frequencies are based on, so I've seen my share of non-standard baud rates debugging it as I went from board to board that had different frequencies).

I'm also putting this out as a kind of test to see if I can find people who have done this sort of thing, or would like to. I'm not sure of how well Google covers blogs, so now I have something to search on.

In the future, I'll try to see if I can kick this CPU into a 'useful' recovery mode so I can just take over from scratch before redboot even gets around to starting :-0

7 comments:

Anonymous said...

would be brilliant to get to alternate various things inside this nas' config, such software would always improve the usability of such a product, keep on going :D

deichert said...

Hmmm, do you know if there is a serial line driver chip on the 4100? This sounds similiar to what I've seen on other embedded systems that are to cheap to add a MAX3232 chip.

deichert

Warner Losh said...

Hmmm, do you know if there is a serial line driver chip on the 4100? This sounds similiar to what I've seen on other embedded systems that are to cheap to add a MAX3232 chip.

There's some TI chip that's used as the level converter. There's other posts that I've stumbled upon for other embedded devices that lead to a clue. There's one gentleman who is having issues similar to mine (the characters look the same in the screen shot he's posted). It was suggested that there's some mixup between GND and VCC which is causing issues. When I get some time, I plan on connecting the USB to 3.3V adapter I have for another project. That may be sufficient to break into this box.

I foolishly thought that if I soldered the serial port to the header everything would be OK. It appears that there's some problem with doing that. The TI chip I chased down shows that there's supposed to be level conversion, but something isn't working quite right. Maybe there's some jumper that needs to be installed as well. Going back to the output of the ARM chip may be profitable.

Anonymous said...

My n4100 (VER: 1.0) has a TI MAX3243, which is an RS232 level conversion chip. I can't find where its pins are actually going, however. They don't appear to go to CJ1. And CN1 looks like a JTAG connector.

Where is this "serial port header" of which you speak?

b.g. bgat@billgatliff.com

Anonymous said...

I also thought buying one of these would help OpenBSD/armish get better - but I get nothing on my screen, even though my model did include the header.

If you get something to boot on this and give output on serial please tell the world :-)

Henrik Kramshøj
hlk@kramse.dk

Imagetaylor said...

It would be great to get something like openfiler installed

Anonymous said...

The web based software is so full of vulnerabilities its not funny, you might want to go that route.

You can replace almost any file on the filesystem using a directory traversal bug in the web share software.

Granted, some people have made this easy by writing modules that will give you root access.