MC68HC908GR8 Datasheet, PDF (25/286 Pages) Freescale Semiconductor, Inc – M68HC08 Microcontrollers

Pin Functions
1.5.6 External Filter Capacitor Pin (CGMXFC)
CGMXFC is an external filter capacitor connection for the CGM. See Chapter 7 Clock Generator Module
(CGMC).
1.5.7 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 Chapter 5 Analog-to-Digital Converter (ADC).
1.5.8 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 Chapter 16 Input/Output Ports (I/O) and See
Chapter 12 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.
1.5.9 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 Chapter 16 Input/Output Ports (I/O) and See Chapter 5 Analog-to-Digital
Converter (ADC).
There are no pullups associated with this port.
1.5.10 Port C I/O Pins (PTC1–PTC0)
PTC1–PTC0 are general-purpose, bidirectional I/O port pins. See Chapter 16 Input/Output Ports (I/O).
PTC0 and PTC1 are only available on 32-pin QFP packages.
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.
1.5.11 Port D I/O Pins (PTD6/T2CH0–PTD0/SS)
PTD6–PTD0 are special-function, bidirectional I/O port pins. PTD3–PTD0 can be programmed to be
serial peripheral interface (SPI) pins, while PTD6–PTD4 can be individually programmed to be timer
interface module (TIM1 and TIM2) pins. See Chapter 22 Timer Interface Module (TIM), Chapter 20 Serial
Peripheral Interface (SPI), and See Chapter 16 Input/Output Ports (I/O).
MC68HC908GR8 • MC68HC908GR4 Data Sheet, Rev. 7
Freescale Semiconductor
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