MC68HC908KX8 Datasheet, PDF (146/310 Pages) Motorola, Inc – Microcontrollers

Configuration Register (CONFIG)
EXTXTALEN — External Crystal Enable Bit
EXTXTALEN enables the external oscillator circuits to be configured
for a crystal configuration where the PTB6/(OSC1) and PTB7/(OSC2)
pins are the connections for an external crystal.
NOTE: This bit does not function without setting the EXTCLKEN bit also.
Clearing the EXTXTALEN bit (default setting) allows the
PTB7/(OSC2) pin to function as a general-purpose I/O pin. Refer to
Table 9-1 for configuration options for the external source. See
Section 7. Internal Clock Generator Module (ICG) for a more
detailed description of the external clock operation.
EXTXTALEN, when set, also configures the clock monitor to expect
an external clock source in the valid range of crystals (30 kHz to
100 kHz or 1 MHz to 8 MHz). When EXTXTALEN is clear, the clock
monitor will expect an external clock source in the valid range for
externally generated clocks when using the clock monitor (60 Hz to
32 MHz).
EXTXTALEN, when set, also configures the external clock
stabilization divider in the clock monitor for a 4096-cycle timeout to
allow the proper stabilization time for a crystal. When EXTXTALEN is
clear, the stabilization divider is configured to 16 cycles since an
external clock source does not need a startup time.
1 = Allows PTB7/(OSC2) to be an external crystal connection.
0 = PTB7/(OSC2) functions as an I/O port pin (default).
OSCENINSTOP — Oscillator Enable In Stop Mode Bit
OSCENINSTOP, when set, will enable the internal clock generator
module to continue to generate clocks (either internal, ICLK, or
external, ECLK) in stop mode. See Section 7. Internal Clock
Generator Module (ICG). This function is used to keep the timebase
running while the rest of the microcontroller stops. See Section 15.
Timebase Module (TBM). When clear, all clock generation will cease
and both ICLK and ECLK will be forced low during stop mode. The
default state for this option is clear, disabling the ICG in stop mode.
1 = Oscillator enabled to operate during stop mode
0 = Oscillator disabled during stop mode (default)
NOTE: This bit has the same functionality as the OSCSTOPENB CONFIG bit in
MC68HC908GP20 and MC68HC908GR8 parts.
Technical Data
146
MC68HC908KX8 • MC68HC908KX2 • MC68HC08KX8 — Rev. 1.0
Configuration Register (CONFIG)
MOTOROLA