MC68HC908QL4 Datasheet, PDF (131/226 Pages) Motorola, Inc – Microcontrollers

13.8 SIM Registers
The SIM has two memory mapped registers.
SIM Registers
13.8.1 SIM Reset Status Register
This register contains seven 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.
Bit 7
6
5
4
3
2
1
Bit 0
Read: POR
PIN
COP
ILOP
ILAD MODRST LVI
0
Write:
POR: 1
0
0
0
0
0
0
0
= Unimplemented
Figure 13-19. SIM Reset Status Register (SRSR)
POR — Power-On Reset Bit
1 = Last reset caused by POR circuit
0 = Read of SRSR
PIN — External Reset Bit
1 = Last reset caused by external reset pin (RST)
0 = POR or read of SRSR
COP — Computer Operating Properly Reset Bit
1 = Last reset caused by COP counter
0 = POR or read of SRSR
ILOP — Illegal Opcode Reset Bit
1 = Last reset caused by an illegal opcode
0 = POR or read of SRSR
ILAD — Illegal Address Reset Bit (illegal attempt to fetch an opcode from an unimplemented
address)
1 = Last reset caused by an opcode fetch from an illegal address
0 = POR or read of SRSR
MODRST — Monitor Mode Entry Module Reset bit
1 = Last reset caused by monitor mode entry when vector locations $FFFE and $FFFF are $FF after
POR while IRQB = V_DD
0 = POR or read of SRSR
LVI — Low Voltage Inhibit Reset bit
1 = Last reset caused by LVI circuit
0 = POR or read of SRSR
MC68HC908QL4 Data Sheet, Rev. 7
Freescale Semiconductor
131