Datasheet

General Description
Pin Functions
MC68HC908GR8 — Rev 4.0 Technical Data
MOTOROLA General Description 33
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 (V
DDAD
/V
REFH
and V
SSAD
/V
REFL
)
V
DDAD
and V
SSAD
are the power supply pins for the analog-to-digital
converter. Decoupling of these pins should be as per the digital supply.
NOTE: V
REFH
is the high reference supply for the ADC. The V
REFH
signal is
internally connected with V
DDAD
and have the same potential as V
DDAD.
V
DDAD
should be tied to the same potential as V
DD
via separate traces.
V
REFL
is the low reference supply for the ADC. The V
REFL
pin is
internally connected with V
SSAD
and has the same potential as V
SSAD.
V
SSAD
should be tied to the same potential as V
SS
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.
Frees
cale Semiconductor,
I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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