Datasheet

System Integration Module (SIM)
SIM Counter
MC68HC908JB8•MC68HC08JB8•MC68HC08JT8 — Rev. 2.3 Technical Data
Freescale Semiconductor System Integration Module (SIM) 103
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.
Table 8-3. Registers not Affected by Normal Reset
Bits Registers
After Reset
(except POR or
LVI)
After POR or LVI
URSTD, LVIDIS CONFIG Unaffected 0
USBEN UADDR Unaffected 0
PULLEN UCR3 Unaffected 0
All USR0, USR1 Unaffected Indeterminate
All UE0D0–UE0D7 Unaffected Indeterminate
All UE1D0–UE1D7 Unaffected Indeterminate
All UE2D0–UE2D7 Unaffected Indeterminate
All
PTA, PTB, PTC,
PTD, and PTE
Unaffected Indeterminate
DDRA7 DDRA Unaffected 0