MC68HC908AZ60 Datasheet, PDF (126/480 Pages) Motorola, Inc – HCMOS Microcontroller Unit

System Integration Module (SIM)
BW can be read within the break state SWI routine. The user can modify
the return address on the stack by subtracting one from it. The following
code is an example of this. Writing zero to the BW bit clears it.
; 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 BW, do RTI
BRCLR BW,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.
SIM Reset Status
Register
This register contains six flags that show the source of the last reset. The
status register will automatically clear after 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
1
Bit 0
Read: POR
PIN
COP ILOP ILAD
0
LVI
0
Write:
POR: 1
0
0
0
0
0
0
0
= Unimplemented
Figure 18. SIM Reset Status Register (SRSR)
POR — Power-On Reset Bit
1 = Last reset caused by POR circuit
0 = Read of SRSR
MC68HC908AZ60 — Rev 2.0
124
System Integration Module (SIM)
20-sim
MOTOROLA