Freescale Semiconductor, Inc.
GENERAL RELEASE SPECIFICATION
1.5.3 OSC1 and OSC2
These pins provide control input for an on-chip clock oscillator circuit. A crystal, a
ceramic resonator, a resistor/capacitor combination, or an external signal
connects to these pins and provides a system clock. A mask option selects either
a crystal/ceramic resonator or a resistor/capacitor as the frequency determining
element. The oscillator frequency is two times the internal bus rate.
1.5.4 RESET
This active low pin is used to reset the MCU to a known start-up state by pulling
RESET low. The RESET pin contains an internal Schmitt trigger as part of its
input to improve noise immunity.
1.5.5 TCMP
This pin provides an output for the output compare feature of the on-chip timer
system.
1.5.6 PA0 through PA7
Port A is an 8-bit bidirectional port which does not share any of its pins with other
subsystems. The port A data register is at $0000, and the data direction register is
at $0004. Reset does not affect the data registers, but clears the data direction
registers, thereby returning the ports to inputs. Writing a one to a DDR bit sets the
corresponding port bit to output mode. Port A has mask option enabled pullup
devices and interrupt capability by pin. For a detailed description of I/O
programming, refer to 1.6 Input/Output Programming.
Rev. 2.0
1-5
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