Fujitsu F2MC-16L Series User Manual page 25

Instruction SPACE
Group RETURN
INT trace
CALL
common
JMP/JCTX
RET/RETI
BRA
Bcc trace both branch and
no branch
Important:
NOTE: The monitor uses the INT9 instruction and the corresponding vector in the user
vector table to realise the Breakpoint and Trace operation. Thus, this instruction must
not be invoked by the user program and the vector at FFFFD8h (equal to the content
of shadow RAM at xFBFFDh) must not be overwritten.
NOTE: As TRACE, STEP, BREAK are realised by INT9, these functions need a valid
system stack when the user program is running or traced. TRACEing, STEPping or
BREAKing an uninitialised program may cause malfunction.
This is important, too, when a valid stack is changed to another valid value. Because
two values (bank and offset) might be changed, there can be an invalid "gap" when the
one has changed but the second part is still to be changed. Depending on whether this
undefined stack pointer is pointing to unused RAM or not, executing an INT9
instruction can cause misoperation.
E.g.: The current system stack pointer value is F80157h in the lower area of page 8
(RAM 0). This value is to be changed to an area in page A, to FA8000h. After setting
SSB to the new value (FAh) the system stack pointer is pointing to FA0157:
MOV A,#H'FA
MOV SSB,A
After this instruction the system pointer of the user program points within the monitor
data area. When the INT9-instruction is executed (TRACE step or breakpoint), the
stack operation may destroy monitor data.
MOVW A,#H'80000
MOVW SP,A
After this instruction the stack is defined and all trace functions can be used.
This problem will normally occur only in the start routine (INIT16L.ASM-module),
that can be skipped by "GO _start _main" command. The advanced programmer can
use register setting commands before critical trace steps to define a useful temporary
system stack. If the monitor command
>register SSP 8000↵
is requested before tracing the "MOV SSB,A" instruction, there will be no problem.
© FUJITSU Mikroelektronik GmbH 1996
FUJITSU MB90675-Evaluation Board - User Manual
O V
(Over) (oVer)
trace over
trace
trace only
branch
R B
(oveR) (Branch)
abort
trace over branch
branch always
; S-flag set of course
N X
(Next) eXit
abort
branch
never
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