ARM Technical Support Knowledge Articles

LPC2000 SINGLE STEP AT RESET APPEARS TO FAIL

Applies to: ULINK USB-JTAG Debugger

Answer


Information in this article applies to:


QUESTION

I am using the Keil ULINK on a Philips/NXP LPC2000 target hardware. When I start a debugging session (with 'Run to main()' turned off) or when I reset the CPU the program counter is at its reset address. From there I execute single steps and expect to go through the STARTUP.S file. Instead the system jumps to the 0xFFFFxxxx region and stays there.

What causes this behavior?

ANSWER

The NXP LPC2000 devices have built-in boot firmware which executes after CPU reset. What you actually see is the execution of this boot firmware. Since the boot firmware disables the JTAG interface with one of the first instructions it is not possible to step through it. When the program counter is on the reset address (0x0000 when on-chip flash is used) there are two ways to reach the startup code:

Now, you can single step through the startup code.

MORE INFORMATION

SEE ALSO

Article last edited on: 2007-01-28 19:21:02

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