Freescale Semiconductor, Inc.
System Integration Module (SIM)
Reset and System Initialization
OSC1
PORRST
4096
CYCLES
32
CYCLES
32
CYCLES
CGMXCLK
CGMOUT
RST
IAB
$FFFE
$FFFF
Figure 9-7. POR Recovery
9.4.2.2 Computer Operating Properly (COP) Reset
The overflow of the COP counter causes an internal reset and sets the
COP bit in the SIM reset status register (SRSR) if the COPD bit in the
CONFIG-1 register is at logic 0. See Section 14. Computer Operating
Properly (COP) Module.
9.4.2.3 Illegal Opcode Reset
The SIM decodes signals from the CPU to detect illegal instructions. An
illegal instruction sets the ILOP bit in the SIM reset status register
(SRSR) and causes a reset.
If the stop enable bit, STOP, in the CONFIG-1 register is logic 0, the SIM
treats the STOP instruction as an illegal opcode and causes an illegal
opcode reset.
9.4.2.4 Illegal Address Reset
An opcode fetch from an unmapped address generates an illegal
address reset. The SIM verifies that the CPU is fetching an opcode prior
to asserting the ILAD bit in the SIM reset status register (SRSR) and
resetting the MCU. A data fetch from an unmapped address using
MC68HC908AS60 — Rev. 1.0
Technical Data
System Integration Module (SIM)
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