MC9S08QD4_07 Datasheet, PDF (62/202 Pages) Freescale Semiconductor, Inc – 8-Bit HCS08 Central Processor Unit (CPU)

Chapter 5 Resets, Interrupts, and General System Control
Table 5-4. SRS Register Field Descriptions (continued)
Field
5
COP
4
ILOP
3
ILAD
1
LVD
Description
Computer Operating Properly (COP) Watchdog — Reset was caused by the COP watchdog timer timing out.
This reset source can be blocked by COPE = 0.
0 Reset not caused by COP timeout.
1 Reset caused by COP timeout.
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.
Illegal Address — Reset was caused by an attempt to access either data or an instruction at an unimplemented
memory address.
0 Reset not caused by an illegal address
1 Reset caused by an illegal address
Low Voltage Detect — If the LVDRE bit is set and the supply drops below the LVD trip voltage, an LVD reset will
occur. This bit is also set by POR.
0 Reset not caused by LVD trip or POR.
1 Reset caused by LVD trip or POR.
5.8.3 System Background Debug Force Reset Register (SBDFR)
This high-page register contains a single write-only control bit. A serial background command such as
WRITE_BYTE must be used to write to SBDFR. Attempts to write this register from a user program are
ignored. Reads always return 0x00.
7
6
5
4
3
2
1
R
0
0
0
0
0
0
0
W
Reset:
0
0
0
0
0
0
0
= Unimplemented or Reserved
1 _{BDFR is writable only through serial background debug commands, not from user programs.}
Figure 5-4. System Background Debug Force Reset Register (SBDFR)
0
0
BDFR¹
0
Field
0
BDFR
Table 5-5. SBDFR Register Field Descriptions
Description
Background Debug Force Reset — A serial background command such as WRITE_BYTE can be used to allow
an external debug host to force a target system reset. Writing 1 to this bit forces an MCU reset. This bit cannot
be written from a user program. To enter user mode, PTA4/TPM2CH0O/BKGD/MS must be high immediately
after issuing WRITE_BYTE command. To enter BDM, PTA4/TPM2CH0O/BKGD/MS must be low immediately
after issuing WRITE_BYTE command. See A.8.1, “Control Timing,” for more information.
MC9S08QD4 Series MCU Data Sheet, Rev. 3
62
Freescale Semiconductor