MC68HC705P9 Datasheet, PDF (17/156 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Pin Descriptions
Pin Functions
NOTE:
Because the frequency stability of ceramic resonators is not as high as
that of crystal oscillators, using a ceramic resonator may degrade the
performance of the ADC.
External Clock
Connections
RESET
An external clock from another
CMOS-compatible device can
drive the OSC1 input, with the
OSC2 pin unconnected, as
Figure 5 shows.
A logic zero on the RESET pin
forces the MCU to a known
startup state. The RESET pin
input circuit contains an internal
Schmitt trigger to improve noise
immunity.
MCU
EXTERNAL
CMOS CLOCK
UNCONNECTED
Figure 5. External Clock
Connections
IRQ/V_PP
PA7–PA0
The IRQ/V_PP pin has the following functions:
• Applying asynchronous external interrupt signals
• Applying V_PP, the EPROM/OTPROM programming voltage
PA7–PA0 are general-purpose bidirectional I/O port pins. Use data
direction register A to configure port A pins as inputs or outputs.
PB7/SCK–
PB5/SDO
Port B is a 3-pin bidirectional I/O port that shares its pins with the SIOP.
Use data direction register B to configure port B pins as inputs or
outputs.
PC7/V_RH–PC0
Port C is an 8-pin bidirectional I/O port that shares five of its pins with the
ADC. Use data direction register C to configure port C pins as inputs or
outputs.
5-mc68hc705p9
MOTOROLA
Pin Descriptions
17