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MC68HC908GR16 Datasheet, PDF (25/276 Pages) Motorola, Inc – Microcontrollers
Pin Functions
1.5.5 CGM Power Supply Pins (VDDA and VSSA)
VDDA and VSSA are the power supply pins for the analog portion of the clock generator module (CGM).
Decoupling of these pins should be as per the digital supply. See Chapter 4 Clock Generator Module
(CGM).
1.5.6 External Filter Capacitor Pin (VCGMXFC)
CGMXFC is an external filter capacitor connection for the CGM. See Chapter 4 Clock Generator Module
(CGM).
1.5.7 ADC Power Supply/Reference Pins (VDDAD/VREFH and VSSAD/VREFL)
VDDAD and VSSAD are the power supply pins to the analog-to-digital converter (ADC). VREFH and VREFL
are the reference voltage pins for the ADC. VREFH is the high reference supply for the ADC, and by default
the VDDAD/VREFH pin should be externally filtered and connected to the same voltage potential as VDD.
VREFL is the low reference supply for the ADC, and by default the VSSAD/VREFL pin should be connected
to the same voltage potential as VSS. See Chapter 3 Analog-to-Digital Converter (ADC).
1.5.8 Port A Input/Output (I/O) Pins (PTA7/KBD7–PTA0/KBD0)
PTA7–PTA0 are general-purpose, bidirectional I/O port pins. Any or all of the port A pins can be
programmed to serve as keyboard interrupt pins. See Chapter 12 Input/Output Ports (PORTS) and
Chapter 9 Keyboard Interrupt Module (KBI).
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.
1.5.9 Port B I/O Pins (PTB7/AD7–PTB0/AD0)
PTB7–PTB0 are general-purpose, bidirectional I/O port pins that can also be used for analog-to-digital
converter (ADC) inputs. See Chapter 12 Input/Output Ports (PORTS) and Chapter 3 Analog-to-Digital
Converter (ADC).
1.5.10 Port C I/O Pins (PTC6–PTC0)
PTC6 and PTC5 are general-purpose, bidirectional I/O port pins. PTC4–PTC0 are general-purpose,
bidirectional I/O port pins that contain higher current sink/source capability. See Chapter 12 Input/Output
Ports (PORTS).
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 (PTD7/T2CH1–PTD0/SS)
PTD7–PTD0 are special-function, bidirectional I/O port pins. PTD3–PTD0 can be programmed to be
serial peripheral interface (SPI) pins, while PTD7–PTD4 can be individually programmed to be timer
interface module (TIM1 and TIM2) pins. See Chapter 18 Timer Interface Module (TIM), Chapter 16 Serial
Peripheral Interface (SPI) Module, and Chapter 12 Input/Output Ports (PORTS).
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.
MC68HC908GR16 Data Sheet, Rev. 5.0
Freescale Semiconductor
25