mc68hc05bs8 Freescale Semiconductor, Inc, mc68hc05bs8 Datasheet - Page 21

• Manufacturer Part Number: mc68hc05bs8
• Description: Mc68hc05 Family Of Low-cost Single-chip Microcontrollers.
• Manufacturer: Freescale Semiconductor, Inc

This section provides a description of the functional pins of the MC68HC05BS8 microcontroller.
2.1
MC68HC05BS8
VDD, VSS
IRQ/ VPP
RESET
OSC1, OSC2
PA0-PA7
PIN NAME
Pin Descriptions
44-pin QFP
PIN No.
38, 39
36, 37
33-26
34
35
PIN DESCRIPTION
Power is supplied to the MCU using these pins. VDD is the positive power supply;
VSS is ground.
In the user mode this pin is the external hardware interrupt IRQ. Two choices of
interrupt triggering sensitivity are available through the Option register:
In bootstrap mode on the MC68HC705BS8, this is the EPROM programming
voltage input pin.
The active low RESET input is not required for start-up, but can be used to reset
the MCU internal state and provide an orderly software start-up procedure.
These pins provide connections to the
on-chip oscillator. The oscillator can be
driven by an AT-crystal circuit or a
ceramic resonator with a maximum
frequency of 4.4MHz. OSC1 may also
be driven by an external oscillator if an
external crystal/resonator circuit is not
used.
Example showing crystal connections.
These eight I/O lines comprise port A. The state of any pin is software
programmable. All port A lines are configured as input during power-on or external
reset.
PIN DESCRIPTION
1) negative-edge sensitive triggering, or
2) negative-level sensitive triggering.
2
DESCRIPTION
36pF
OSC1
4.2MHz
2M
MCU
36pF
OSC2
TPG
2