MC68HC908KX2 MOTOROLA [Motorola, Inc], MC68HC908KX2 Datasheet - Page 145

• Manufacturer Part Number: MC68HC908KX2
• Description: Microcontrollers
• Manufacturer: MOTOROLA [Motorola, Inc]

MC68HC908KX8 • MC68HC908KX2 • MC68HC08KX8 — Rev. 1.0
MOTOROLA
EXTCLKEN
Configuration Bits
0
0
1
1
External Clock
EXTXTALEN
0
1
0
1
EXTCLKEN — External Clock Enable Bit
EXTSLOW — Slow External Crystal Enable Bit
Table 9-1. External Clock Option Settings
EXTCLKEN enables an external clock source or crystal/ceramic
resonator to be used as a clock input. Setting this bit enables
PTB6/(OSC1) pin to be a clock input pin. Clearing this bit (default
setting) allows the PTB6/(OSC1) and PTB7/(OSC2) pins to function
as a general-purpose input/output (I/O) pin. Refer to
configuration options for the external source. See
Clock Generator Module (ICG)
external clock operation.
The EXTSLOW bit has two functions. It configures the ICG module for
a fast (1 MHz to 8 MHz) or slow (30 kHz to 100 kHz) speed crystal.
The option also configures the clock monitor operation in the ICG
module to expect an external frequency higher (307.2 kHz to 32 MHz)
or lower (60 Hz to 307.2 kHz) than the base frequency of the internal
oscillator. See
PTB6/(OSC1)
1 = Allows PTB6/(OSC1) to be an external clock connection
0 = PTB6/(OSC1) and PTB7/(OSC2) function as I/O port pins
1 = ICG set for slow external crystal operation
0 = ICG set for fast external crystal operation
OSC1
OSC1
PTB6
PTB6
(default).
Configuration Register (CONFIG)
Pin Function
Section 7. Internal Clock Generator Module
PTB7/(OSC2)
OSC2
PTB7
PTB7
PTB7
Default setting — external oscillator disabled
External oscillator disabled since EXTCLKEN
External oscillator configured for an external
External oscillator configured for an external
not set
clock source input (square wave) on OSC1
crystal configuration on OSC1 and OSC2.
System will also operate with square-wave
clock source in OSC1.
for a more detailed description of the
Configuration Register (CONFIG)
Description
Section 7. Internal
Functional Description
Table 9-1
Technical Data
(ICG).
for
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