This page will try to explain my experience with jtag cable.

Contents: [Dobrica Pavlinušić's random unstructured stuff]
• Dobrica Pavlinušić's random unstructured stuff (Hardware) 
• Dobrica Pavlinušić's random unstructured stuff (Software) 
• Dobrica Pavlinušić's random unstructured stuff (dependencies) 
• Dobrica Pavlinušić's random unstructured stuff (checkout source) 
• Dobrica Pavlinušić's random unstructured stuff (include) 
• Dobrica Pavlinušić's random unstructured stuff (jtag) 
• Dobrica Pavlinušić's random unstructured stuff (Connect to device) 
• Dobrica Pavlinušić's random unstructured stuff (Load kernel module) 
• Dobrica Pavlinušić's random unstructured stuff (Start jtag tool) 

Hardware
• JTAG cable 
Software
Currently supported jtag utility is UrJTAG 
dependencies
apt-get install libreadline-dev

checkout source
svn co https://urjtag.svn.sourceforge.net/svnroot/urjtag/trunk urjtag
cd unrjtag

include
cd include
./autogen.sh
sudo make install
cd ..

jtag
cd jtag
./autogen.sh
make
make install

Connect to device
Load kernel module
modprobe ppdev

Start jtag tool
$ jtag
jtag> cable ppdev /dev/parport0 WIGGLER
Initializing Macraigor Wiggler JTAG Cable on ppdev port /dev/parport0
jtag> detect