MC68HC08GP32A Datasheet, PDF (24/258 Pages) Freescale Semiconductor, Inc – Microcontrollers

General Description
1.6 Pin Functions
Descriptions of the pin functions are provided here.
1.6.1 Power Supply Pins (V_DD and V_SS)
V_DD and V_SS are the power supply and ground pins. The MCU operates from a single power supply.
Fast signal transitions on MCU pins place high, short-duration current demands on the power supply. To
prevent noise problems, take special care to provide power supply bypassing at the MCU as Figure 1-4
shows. Place the C1 bypass capacitor as close to the MCU as possible. Use a high-frequency-response
ceramic capacitor for C1. C2 is an optional bulk current bypass capacitor for use in applications that
require the port pins to source high current levels.
MCU
V_DD
V_SS
C1
0.1 µF
+
C2
V_DD
Note: Component values shown represent typical applications.
Figure 1-4. Power Supply Bypassing
1.6.2 Oscillator Pins (OSC1 and OSC2)
The OSC1 and OSC2 pins are the connections for the on-chip oscillator circuit. See Chapter 4 Clock
Generator Module (CGM).
1.6.3 External Reset Pin (RST)
A low on the RST pin forces the MCU to a known startup state. RST is bidirectional, allowing a reset of
the entire system. It is driven low when any internal reset source is asserted. This pin contains an internal
pullup resistor. See Chapter 15 System Integration Module (SIM).
1.6.4 External Interrupt Pin (IRQ)
IRQ is an asynchronous external interrupt pin. This pin contains an internal pullup resistor. See
Chapter 7 External Interrupt (IRQ)
MC68HC08GP32A • MC68HC08GP16A Data Sheet, Rev. 1.0
24
Freescale Semiconductor