AVR-Chat

--- In AVR-Chat@yahoogroups.com, wagnerj@... wrote:
> I think this is an inherent limit due to JTAG debugging.
> You don't get history information out of JTAG.
Some ICE debuggers implement an execution trace buffer (JTAG does not) but that is not what the OP was referring to.  If the stack frames are set up to support it, the debugging software can "walk" the stack to determine the calling context, e.g. A called B called C called D where it hit the breakpoint and stopped execution.  Microsoft VisualStudio does this very well for C/C++, showing the parameter values passed, the point at which each nested invocation was called, etc.

Breakpoints aren't particularly useful for debugging some types of realtime systems, e.g. one in which you can't afford to stop the processor for any significant amount of time.  In these situations you have to instrument your code to allow it either to record important data to be examined at the end of a "run" or to output important data for analysis in real time by another computer, e.g. a PC.  Indicator LEDs and other types of information displays may be useful as well when the system cannot be stopped.

Don Kinzer
ZBasic Microcontrollers
http://www.zbasic.net