M68HC08 datasheet(19/124 Pages) FREESCALE

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Functional Pin Descriptions

MC68HC05C9A Advance Information Data Sheet, Rev. 5.1

Freescale Semiconductor

Figure 1-6. 44-Pin QFP Pin Assignments

NOTE

If MC68HC705C9A devices are to be used in the same socket, pin 43

should be tied to VDD.

1.5.1 VDD and VSS

Power is supplied to the MCU using these two pins. VDD is the positive supply and VSS is ground.

1.5.2 IRQ

This interrupt pin has an option that provides two different choices of interrupt triggering sensitivity.

The IRQ pin contains an internal Schmitt trigger as part of its input to improve noise immunity. Refer to

Chapter 4 Interrupts for more detail.

1.5.3 OSC1 and OSC2

These pins provide control input for an on-chip clock oscillator circuit. A crystal or ceramic resonator

connected to these pins provides a system clock. The internal frequency is one-half the crystal frequency.

1.5.4 RESET

As an input pin, this active low RESET pin is used to reset the MCU to a known startup state by pulling

RESET low. As an output pin, the RESET pin indicates that an internal MCU reset has occurred. The

PC3

PC2

PC1

PC0

PD0/RDI

PD1/TDO

PD2/MISO

PD3/MOSI

PD4/SCK

PD5/SS

TCMP

PA6

PA5

PA4

PA3

PA2

PA1

PA0

PB0

PB1

PB2

PB3

M68HC08 Datasheet(PDF) 19 Page - Freescale Semiconductor, Inc