This is going to be a bit long. What I want to explain is what is going on when you attempt to port a modern operating system to a hardware platform. The things to remember are many, and you need to be aware of them
I am putting this at the beginning since it is important. Porting an OS to a hardware platform is difficult, but there are different levels of difficulties. Math is difficult simply because it seems unrelated to reality (I am talking about advanced math) and the real difficulty of math is to be able to take it down to everyday life. Engineering (mechanical/civil) is difficult because you cannot really test your "building" until you build it, and once it is finished it better be OK. Porting a full OS to an hardware platform requires precision, patience, and the will to never let go. Something that is not for everybody. I didn't mention a extraordinary knowledge of computing HW and SW, but this is obious, isn't it ?
I am assuming here that your board is working, this means that a tiny four lines assembler program that blinks the usual LED does actually make the led blink. We have not yet come to enabling RAM, peripheral and all the rest, but at least the processors is working.
JTAG is a standard that allows an external machine to inquire about your inner board configuration and working. It also allows you to change software bits and pieces of your system. This seems all good and it would actually be good if it was standard all the way trough.
The main problem of JTAG is that it allows you to talk to your board but then you need to be able to speak the language of your components. This means that it is not enough to have a JTAG pod (including the correct connectors), you also need to have the correct software that will let you talk to all the components of your board.
If you are new to the field, just buy the reasonably cheap JTAG debugger and once you have mastered all the concepts of it you will be ready to buy the proper one, knowing what you are going to buy. I have got a cheap and reasonably good pod from Olimex and especially it comes with Linux support.
to be continued.......
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