mc68hc908sr12 Freescale Semiconductor, Inc, mc68hc908sr12 Datasheet - Page 149

• Manufacturer Part Number: mc68hc908sr12
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

9.4.2.2 Computer Operating Properly (COP) Reset
MC68HC908SR12•MC68HC08SR12 — Rev. 5.0
Freescale Semiconductor
CGMOUT
PORRST
OSC1
ICLK
IRST
RST
IAB
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 5
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 pin is held at
V
disabled only through combinational logic conditioned with the high
voltage signal on the RST or the IRQ1 pin. This prevents the COP from
becoming disabled as a result of external noise. During a break state,
V
13
TST
TST
CYCLES
4096
– 2
while the MCU is in monitor mode. The COP module can be
on the RST pin disables the COP module.
4
ICLK cycles, drives the COP counter. The COP should be
Figure 9-7. POR Recovery
System Integration Module (SIM)
CYCLES
32
CYCLES
32
$FFFE
System Integration Module (SIM)
Reset and System Initialization
$FFFF
Data Sheet
149