Fujitsu MB91401 Notes Of Debug, Step execution of RETI instruction, Operand break, Trace mode

MB91401	Prelminary
	2004.11.12

■NOTES OF DEBUG

Step execution of RETI instruction

In an environment where interrupts frequently occur during single-step execution, only the relevant interrupt processing routines are executed repeatedly during single-step execution of the RETI instruction. This will prevent the main routine and low-interrupt-level programs from being executed.

Do not execute step of RETI instruction for escape.

When the relevant interrupt routine no longer requires being debugged, disable the relevant interrupt and perform debugging.

Operand break

Do not set the access which is used for area, including the address of system stack pointer, to the target of data event break.

Interrupt handler to NMI request (tool)

To prevent the malfunction because of the noise problem of DSU pin when ICE is unconnected, the following programs are added to the interrupt handler by the cause flag, which is only set by the break request from ICE. ICE can be used even if this program is added.

Location to added

The following interrupt handler

Interrupt resource	: NMI request (tool)
Interrupt number	: 13 (decimal), 0D (hexadecimal)
Offset	: 3C8H
TBR is default address.	: 000FFFC8H

Additional program

STM	(R0, R1)
LDI	#B00H, R0	; B00H is address of the break resource register.
LDI #0, R1
STB	R1, @R0	; Clear the break resource register.
LDM	(R0, R1)

RETI

Trace mode

If the trace mode is set to "Full trace mode" during debug (in full trace mode, built-in FIFO is used as output buffer, the trace memory of the main body of ICE is used, and the trace data lost is not occurred), the electric current is increased and D-busDMA access may be lost.

Also, the trace data lost may be occurred.

To take the measures, do not set full trace mode.

Simultaneous generation of a software break and a user interrupt/NMI

When a software break and a user interrupt/NMI occur simultaneously, the emulator debugger may react as follows.

•The debugger stops pointing to a location other than the programmed breakpoints.

•The halted program is not re-executed correctly.

When these problems are occurred, not only the software break, the hardware break should also be used. Do not set the break to the corresponding location when using monitor debugger.

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