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Hi Guys, May be very basic question. I want to understand how JTAG debugger and Break point works.
Can any one help here...?
Abhijit Dhopate
Note that, strictly, "JTAG" just refers to the communication interface by which you connect to the target and communicate with the on-board debug hardware.
The on-board debug hardware has links to the data bus, address bus, and internal CPU features (registers, etc) to allow it to read and (in some cases) modify them. And a breakpoint signal that allows it to stop (or "freeze") the CPU.
The on-board debug hardware also has its own registers that can be programmed (via the JTAG interface) and, when a "match" is seen in the target hardware, the breakpoint occurs. Some debug hardware also has advanced features like Trace...
I just put "how does a jtag debugger work" into google and got this as the very first hit: instruct1.cit.cornell.edu/.../index.html
I suggest you do the same, and then get googling yourself.
en.wikipedia.org/.../Joint_Test_Action_Group also has a load of links...
Also look at the ARM technical documentation: infocenter.arm.com/.../index.jsp www.arm.com/.../index.php