MC68181 Datasheet, PDF (7/119 Pages) Freescale Semiconductor, Inc – Advance Information ROAMING FLEX chip SIGNAL PROCESSOR

Freescale Semiconductor, Inc.
MC68181
Processor Clock
PROCESSOR CLOCK
Signal
Name
CLKOUT
SYMCLK
EXTAL
XTAL
OSCPD
Table 1-3 Processor Clock Signals
Type
Output
Output
Input
Output
Input
State During
Reset
Signal Description
Indeterminate
Clock Output—This is typically a 38.4 kHz clock output (derived
from 76.8 kHz oscillator).
Indeterminate
Recovered Symbol Clock—Data is synchronized to the internal
clock and this recovered clock output enhances lockon capability
by reducing jitter from cable-induced noise.
Input
External Clock/Crystal Input—EXTAL interfaces the internal
crystal oscillator input to a 76.8 kHz crystal input or other external
input clock.
Indeterminate
External Clock/Crystal Output—This is typically a 76.8 kHz
clock output.
Input
Oscillator Power Down—This input determines whether the
internal oscillator is used. Connect this pin to V_SS when using the
76.8 kHz crystal input. Connect this pin to V_DD when using an
external input clock signal.
RESET
Signal Name
RESET
Table 1-4 Test and Reset Signals
Type
Input
State During
Reset
Signal Description
Input
Reset—This input is a direct hardware reset on the FLEX™ chip
IC. When RESET is asserted low, the FLEX™ chip IC is
initialized and placed in the Reset state.
CURRENT SYMBOL INPUTS
Signal Name
EXTS1
EXTS0
Table 1-5 Interrupt and Mode Control
Type
State During
Reset
Signal Description
Input Input
External Symbol 1—This is the Most Significant Bit (MSB) of
the symbol being tested.
Input Input
External Symbol 0—This is the Least Significant Bit (LSB) of
the symbol being tested.
MOTOROLA
MC68181 Technical Data Sheet
1-3
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