MC68HC908JB8 Datasheet, PDF (103/286 Pages) Motorola, Inc – MICROCONTROLLERS

System Integration Module (SIM)
SIM Counter
Table 8-3. Registers not Affected by Normal Reset
Bits
URSTD, LVIDIS
USBEN
PULLEN
All
All
All
All
All
DDRA7
Registers
CONFIG
UADDR
UCR3
USR0, USR1
UE0D0–UE0D7
UE1D0–UE1D7
UE2D0–UE2D7
PTA, PTB, PTC,
PTD, and PTE
DDRA
After Reset
(except POR or
LVI)
Unaffected
Unaffected
Unaffected
Unaffected
Unaffected
Unaffected
Unaffected
After POR or LVI
0
0
0
Indeterminate
Indeterminate
Indeterminate
Indeterminate
Unaffected
Indeterminate
Unaffected
0
8.5 SIM Counter
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 prescalar for the computer operating properly module (COP). The SIM
counter uses 12 stages for counting, followed by a 13th stage that
triggers a reset of SIM counters and supplies the clock for the COP
module. The SIM counter is clocked by the falling edge of OSCXCLK.
8.5.1 SIM Counter During Power-On Reset
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 oscillator to drive the bus clock state machine.
MC68HC908JB8•MC68HC08JB8•MC68HC08JT8 — Rev. 2.3
Freescale Semiconductor
System Integration Module (SIM)
Technical Data
103