Resets, Interrupts, and System Conguration
MC9S08RC/RD/RE/RG Data Sheet, Rev. 1.11
66
Freescale Semiconductor
76543210
R
POR
PIN
COP
ILOP
ILAD
(1)
1. The ILAD bit is only present in 16K and 8K versions of the devices.
0
LVD
0
W
Writing any value to SRS address clears COP watchdog timer.
POR
10000010
LVR
u0000010
Any other
reset:
0
(2)
2. Any of these reset sources that are active at the time of reset will cause the corresponding bit(s) to be set; bits corresponding
to sources that are not active at the time of reset will be cleared.
(2)
000
u = Unaffected by reset
Figure 5-3. System Reset Status (SRS)
Table 5-3. SRS Field Descriptions
Field
Description
7
POR
Power-On Reset — Reset was caused by the power-on detection logic. Because the internal supply voltage was
ramping up at the time, the low-voltage reset (LVR) status bit is also set to indicate that the reset occurred while
the internal supply was below the LVR threshold.
0 Reset not caused by POR.
1 POR caused reset.
6
PIN
External Reset Pin — Reset was caused by an active-low level on the external reset pin.
0 Reset not caused by external reset pin.
1 Reset came from external reset pin.
5
COP
Computer Operating Properly (COP) Watchdog — Reset was caused by the COP watchdog timer timing out.
This reset source may be blocked by COPE = 0.
0 Reset not caused by COP timeout.
1 Reset caused by COP timeout.
4
ILOP
Illegal Opcode — Reset was caused by an attempt to execute an unimplemented or illegal opcode. The STOP
instruction is considered illegal if stop is disabled by STOPE = 0 in the SOPT register. The BGND instruction is
considered illegal if active background mode is disabled by ENBDM = 0 in the BDCSC register.
0 Reset not caused by an illegal opcode.
1 Reset caused by an illegal opcode.
3
ILAD
Illegal Address Access — Reset was caused by an attempt to access a designated illegal address.
0 Reset not caused by an illegal address access
1 Reset caused by an illegal address access
Illegal address areas only exist in the 16K and 8K versions and are dened as:
$0440–$17FF — Gap from end of RAM to start of high-page registers
$1834–$BFFF — Gap from end of high-page registers to start of FLASH memory
Unused and reserved locations in register areas are not considered designated illegal addresses and do not
trigger illegal address resets.
1
LVD
Low Voltage Detect — If the LVDRE bit is set and the supply drops below the LVD trip voltage, an LVD reset
occurs. This bit is also set by POR.
0 Reset not caused by LVD trip or POR
1 Reset caused by LVD trip or POR