MC68HC05P18A Datasheet, PDF (22/130 Pages) Freescale Semiconductor, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
General Description
1.5.2.2 Ceramic Resonator
In cost-sensitive applications, a ceramic resonator can be used in place
of the crystal. The circuit in Figure 1-3 (a) can be used for a ceramic
resonator.
NOTE:
The crystal manufacturer’s recommendations should be followed, as the
crystal parameters determine the external component values required to
provide maximum stability and reliable startup.
The load capacitance values used in the oscillator circuit design should
include all stray capacitances. Mount the resonator and components as
close as possible to the pins for startup stabilization and to minimize
output distortion.
1.5.2.3 External Clock
An external clock from another CMOS-compatible device can be
connected to the OSC1 input, with the OSC2 input not connected, as
shown in Figure 1-3 (b).
1.5.3 Reset (RESET)
Driving this input low resets the MCU to a known startup state. As an
output pin, the RESET pin indicates that an internal MCU reset has
occurred. The RESET pin contains an internal Schmitt trigger to improve
its noise immunity. Refer to Section 5. Resets.
1.5.4 Port A (PA0–PA7)
Port A is comprised of eight I/O pins (PA0–PA7). The state of any pin is
software programmable and all port A lines are configured as inputs
during power-on or reset. Eight mask options can be chosen to enable
pullups and interrupts (active low) on port A pins (see 1.4 Mask
Options). Refer to Section 7. Input/Output (I/O) Ports and Section 4.
Interrupts.
Technical Data
General Description
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MC68HC05P18A