MC68HC08BD24 Datasheet, PDF (99/244 Pages) Motorola, Inc – HCMOS Microcontroller Unit

SBSW can be read within the break interrupt routine. The user can
modify the return address on the stack by subtracting one from it. The
following code is an example.
;This code works if the H register has been pushed onto the stack in the break
;service routine software. This code should be executed at the end of the break
;service routine software.
HIBYTE EQU
5
LOBYTE EQU
6
;
If not SBSW, do RTI
BRCLR SBSW,SBSR, RETURN
;See if wait mode or stop mode was exited by
;break.
TST
LOBYTE,SP
;If RETURNLO is not zero,
BNE
DOLO
;then just decrement low byte.
DEC
HIBYTE,SP
;Else deal with high byte, too.
DOLO
DEC
LOBYTE,SP
;Point to WAIT/STOP opcode.
RETURN PULH
RTI
;Restore H register.
7.8.2 SIM Reset Status Register (SRSR)
This register contains six flags that show the source of the last reset.
Clear the SIM reset status register by reading it. A power-on reset sets
the POR bit and clears all other bits in the register.
Address: $FE01
Bit 7
6
5
4
3
2
Read: POR
PIN
COP
ILOP
ILAD
0
1
Bit 0
0
0
Write:
POR: 1
0
0
0
0
0
0
0
= Unimplemented
Figure 7-19. SIM Reset Status Register (SRSR)
POR — Power-On Reset Bit
1 = Last reset caused by POR circuit
0 = Read of SRSR
MC68HC08BD24 — Rev. 1.1
Freescale Semiconductor
Technical Data
99