JTAG stands for "Joint Test Action Group"

Here is a useful JTAG link: http://hri.sourceforge.net/tools/index.html#jtag

It is a hardware method of talking to memory and flash without requireing any app running on the hardware. In other words: mess up your bootloader and your device is a brick? Use JTAG to install a new working loader.

TimRiker has no more JTAG dongles in stock. See the TimRiker page for details.

More info can be found on

http://www.lart.tudelft.nl/projects/jtag/

including the schematics

http://www.lart.tudelft.nl/projects/jtag/jtag-lart_schematic.pdf

the Bill of Material

http://www.lart.tudelft.nl/projects/jtag/jtag-lart_Rev_X1_BOM.txt

The JTAG dongle hardware distribution from Holly Gates. Contains all gerber files to build your own dongle.

http://www.lart.tudelft.nl/projects/jtag/jtag-lart_Rev_X1.tar.gz

There is updated JFlash software the TuxScreen CVS server

http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/tuxscreen/jflash/

RussDill wrote a JTAG MTD driver

http://russ.dhs.org/jtagmap.html

You need to do the FlashUnlock first to enable overwriting the InfernoLoader

TimRiker does not have full info on the jtag connector pin outs yet. You need to solder on a 13 pin header to J100 as on the picture below. You may want to solder it on the bottom so that the pins face towards the back and then cut a hole in the back of the case. More pics on this later.

Here is the wiring from a working JTAG cable. 1-8d are connectors on the LART JTAG dongle pictured above, 1-13h are the header on the mainboard where 1 starts towards the center of the phone.

GND	1h	1d
	2h
nRESET	3h	6h
	4h
	5h
nTRST	6h	3h
TDO	7h	5d
TDI	8h	4d
TCK	9h	3d
TMS	10h	2d
	11h
VCC 3.3v	12h	6d
GND	13h	8d

Notice that 7d is the clipped pin in the pictures above. It is mapped to nTRST on the LART but not connected on the JTAG dongle. Notice also the loop on the header end between 3h and 6h. 2h, 4h, 5h, 11h and 7d are unconnected.

To make a cable you will need a few parts. This right angle header from RadioShack should work for a connector on 1.5 phones. (13 * 3) = 39 It says it's a 40 pin header, but it's really only 20 pins.

http://www.radioshack.com/searchsku.asp?find=910-2048

At least a 16 possition connector for the dongle side:

http://www.radioshack.com/searchsku.asp?find=910-5431

and at least a 26 pin for the other side

http://www.radioshack.com/searchsku.asp?find=910-5433

and 16 conductor cable, note RS only listed a 20 conductor and that mignt not be available now.

http://www.radioshack.com/searchsku.asp?find=910-3828

You may want to cut a hole in your case and route the header out that way: