mc68hc708mp16 Freescale Semiconductor, Inc, mc68hc708mp16 Datasheet - Page 90

• Manufacturer Part Number: mc68hc708mp16
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

System Integration Module (SIM)
7.4.2.2 Computer Operating Properly (COP) Reset
7.4.2.3 Illegal Opcode Reset
7.4.2.4 Illegal Address Reset
Technical Data
90
An input to the SIM is reserved for the COP reset signal. The overflow of
the COP counter causes an internal reset and sets the COP bit in the
SIM reset status register (SRSR). The SIM actively pulls down the RST
pin for all internal reset sources.
To prevent a COP module timeout, write any value to location $FFFF.
Writing to location $FFFF clears the COP counter and bits 12 through 4
of the SIM counter. The SIM counter output, which occurs at least every
2
serviced as soon as possible out of reset to guarantee the maximum
amount of time before the first timeout.
The COP module is disabled if the RST pin or the IRQ1/V
at V
disabled only through combinational logic conditioned with the high
voltage signal on the RST or the IRQ1/V
from becoming disabled as a result of external noise. During a break
state, V
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.
Because the MC68HC708MP16 has stop mode disabled, execution of
the STOP instruction will cause an illegal opcode reset.
An opcode fetch from addresses other than EPROM or RAM addresses
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 does not generate a reset.
13
– 2
DD
+ V
4
DD
CGMXCLK cycles, drives the COP counter. The COP should be
HI
System Integration Module (SIM)
+ V
while the MCU is in monitor mode. The COP module can be
HI
on the RST pin disables the COP module.
PP
pin. This prevents the COP
MC68HC708MP16
Freescale Semiconductor
PP
pin is held
—
Rev. 3.1