mc68hc08az60 Freescale Semiconductor, Inc, mc68hc08az60 Datasheet - Page 93

• Manufacturer Part Number: mc68hc08az60
• Description: M68hc08 Family Of 8-bit Microcontroller Units Mcus
• Manufacturer: Freescale Semiconductor, Inc

SIM Counter
SIM Counter
During Power-On
Reset
SIM Counter
During Stop Mode
Recovery
SIM Counter and
Reset States
11-sim
MOTOROLA
The SIM counter is used by the power-on reset module (POR) and in
stop mode recovery to allow the oscillator time to stabilize before
enabling the internal bus (IBUS) clocks. The SIM counter also serves as
a prescaler for the computer operating properly module (COP). The SIM
counter overflow supplies the clock for the COP module. The SIM
counter is 12 bits long and is clocked by the falling edge of CGMXCLK.
The power-on reset module (POR) detects power applied to the MCU.
At power-on, the POR circuit asserts the signal PORRST. Once the SIM
is initialized, it enables the clock generation module (CGM) to drive the
bus clock state machine.
The SIM counter also is used for stop mode recovery. The STOP
instruction clears the SIM counter. After an interrupt, break, or reset, the
SIM senses the state of the short stop recovery bit, SSREC, in the mask
option register. If the SSREC bit is a logic one, then the stop recovery is
reduced from the normal delay of 4096 CGMXCLK cycles down to 32
CGMXCLK cycles. This is ideal for applications using canned oscillators
that do not require long start-up times from stop mode. External crystal
applications should use the full stop recovery time, that is, with SSREC
cleared.
External reset has no effect on the SIM counter. See
page 100 for details. The SIM counter is free-running after all reset
states. See
counter control and internal reset recovery sequences.
Freescale Semiconductor, Inc.
For More Information On This Product,
System Integration Module (SIM)
Active Resets from Internal Sources
Go to: www.freescale.com
System Integration Module (SIM)
MC68HC08AZ60 — Rev 1.0
on page 89 for
Stop Mode
SIM Counter
on
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