What is the JTAG board for?

[SRG]

Damn ... I discovered "*-plugs" just a few days after the end of this special offer, sounds bad for me if we really need a JTAG (as it is now stated that's it's the case with this Globalscape answer).

[lou1z]

afaik, the plug comes with debian lenny on it so you don't need the jtag. but if you want to muck about with it ie a different os etc, you will need the jtag.

[SRG]

The problem is that i want to install /boot on the internal flash and everything else on the µSD, and as far as i've understood, i'd need the JTAG board for that i believe (but as i've never played with a real headless server, so who knows).

[peter a]

So for those without the JTAG board, let hope it`s set to multiboot by default, because if it`s set to only boot from the internal NAND flash, you aren`t booting from that microSD card or the Esata port without it.

[patermann]

I just received an answer from Globalscale Technologies, Inc. to my question(s). It clears everything up. To sum up, whoever wants to play with GuruPlug seriously, will apparently need that JTAG board.

Oh well, I didn't really want a GuruPlug anyway! Unfortunately, adding the JTag board takes it up to nearly £150 for the Plus version and I cannot justify paying that sort of money just to experiment with it. Although it is obviously not as convenient as having the whole thing built into a plug, I can get a small netbook (i.e. full computer with screen etc.) for not much more than that!

patermann

[SRG]

Eventually, i'm quite disappointed too, with taxes and the need of the JTAG board, it starts to be indeed quite expensive in the end ... so now i really don't know if i take one GuruPlug+ or not ...

[GrahamM]

I suspect that the JTAG adapter isn't going to be much more than an FTDI two port USB to serial adapter. One port will be for JTAG, and the other port will be a serial port. The JTAG part of it would really be useful if you want to debug the unit, or if you want to recover from a bad/corrupt flash. Otherwise, I suspect that JTAG isn't going to be that useful.

Thus, it might very well be possible to use a USB to serial (at a 3.3V logic level at least) converter to connect to the serial port (such as people have been doing with other routers/access points).

[SRG]

Interesting.
I already have a USB > RS232 adapter, indeed, but never had the opportunity to try it out
(bought for a really small price here : http://www.dealextreme.com/details.dx/sku.5859)

[peter a]

RS232 is the wrong voltage !!

You need 3.3v level , so you need something like this :- http://www.byvac.co.uk/co_serial.php

[McMonster]

Judging from what is in this file and from my research in the Internet I think JTAG board won't be really needed. This file shows UART cable connected directly to the plug and if it is really a fully functional UART port then it should be possible to access the serial console using this cable and a much cheaper UART to miniUSB adapter. The same should apply to JTAG port so hopefully it would even be possible to debrick the plug without buying the board.

But the above are just assumptions and guesses, I don't really have the knowledge or experience, so I would be thankful if someone correct me in case I'm wrong.

[Cloaked Alien]

I messed my boot sequence up (/etc/fstab) first day I got it (yesterday) so I had to use the JTAG to fix it. I had a feeling I was going to do that since I'm still learning =)

[mabuhay]

How did you guys access the GuruPlug without configuring the network and installing ssh over the JTAG-board? I am pretty sure ssh was not installed...
The first thing I did was connecting with my JTAG board to set an IP-address and the default gateway, then I was able to install ssh and connect through ssh from my PC. I have not tried it over Wireless-lan, but it bothered somehow that the wirless-IP was 192.168.1.1 since that was my adsl-router's address and needed as the default gateway.

The JTAG-board is not "really" needed I think. But for everyone who want's to play a little with the GuruPlug, especially with the network configuration, it can be very useful if the network interfaces are configured wrong or anything else happens (like as mentioned, if uboot is messed up).