M68ICS08GR datasheet(33/408 Pages) FREESCALE

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General Description

Pin Functions

MC68HC908GR8 — Rev 4.0

Technical Data

MOTOROLA

General Description

1.6.6 External Filter Capacitor Pin (CGMXFC)

CGMXFC is an external filter capacitor connection for the CGM. See

Clock Generator Module (CGMC).

1.6.7 Analog Power Supply/Reference Pins (VDDAD/VREFH and VSSAD/VREFL)

VDDAD and VSSAD are the power supply pins for the analog-to-digital

converter. Decoupling of these pins should be as per the digital supply.

NOTE:

VREFH is the high reference supply for the ADC. The VREFH signal is

internally connected with VDDAD and have the same potential as VDDAD.

VDDAD should be tied to the same potential as VDD via separate traces.

VREFL is the low reference supply for the ADC. The VREFL pin is

internally connected with VSSAD and has the same potential as VSSAD.

VSSAD should be tied to the same potential as VSS via separate traces.

See Analog-to-Digital Converter (ADC).

1.6.8 Port A Input/Output (I/O) Pins (PTA3/KBD3–PTA0/KBD0)

PTA3–PTA0 are special-function, bidirectional I/O port pins. Any or all of

the port A pins can be programmed to serve as keyboard interrupt pins.

See Input/Output Ports (I/O) and External Interrupt (IRQ).

These port pins also have selectable pullups when configured for input

mode. The pullups are disengaged when configured for output mode.

The pullups are selectable on an individual port bit basis.

When the port pins are configured for special-function mode (KBI),

pullups will be automatically engaged. As long as the port pins are in

special-function mode, the pullups will always be on.

1.6.9 Port B I/O Pins (PTB5/AD5–PTB0/AD0)

PTB5–PTB0 are special-function, bidirectional I/O port pins that can also

be used for analog-to-digital converter (ADC) inputs. See Input/Output

Ports (I/O) and Analog-to-Digital Converter (ADC).

There are no pullups associated with this port.

Freescale Semiconductor, Inc.

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