MC908KX2MDWE Datasheet, PDF (21/210 Pages) Freescale Semiconductor, Inc – High-performance M68HC08 architecture, Fully upward-compatible object code with M6805, M146805, and M68HC05 Families

Pin Assignments
1.4.2 Oscillator Pins (OSC1 and OSC2)
The OSC1 and OSC2 pins are available through programming options in the configuration register. These
pins then become the connections to an external clock source or crystal/ceramic resonator. PTB7 and
PTB6 are not available for the crystal/ceramic resonator option and PTB6 is unavailable for the external
clock source option.
1.4.3 External Interrupt Pin (IRQ1)
IRQ1 is an asynchronous external interrupt pin with an internal pullup resistor. See Chapter 8 External
Interrupt (IRQ).
1.4.4 Port A Input/Output (I/O) Pins (PTA4/KBD4–PTA0/KBD0)
PTA4/KBD4–PTA0/KBD0 is a 5-bit special-function port that shares its pins with the keyboard interrupt
(KBI) module and the 2-channel timer module (TIM).
• Any or all of the port A pins can be programmed to serve as keyboard interrupt pins. The respective
pin utilizes an internal pullup resistor when enabled. See Chapter 9 Keyboard Interrupt Module
(KBI).
• Each port A pin contains a software selectable internal pullup resistor when the general-function
I/O port is configured as an input. See Chapter 11 Input/Output (I/O) Ports (PORTS). The pullup
resistor is automatically disabled once a TIM special function is enabled for that pin.
• All port A pins are high-current source/sink pins.
NOTE
Any unused inputs and I/O ports should be tied to an appropriate logic level
(either V_DD or V_SS). Although the I/O ports of the MC68HC908KX8 do not
require termination, termination is recommended to reduce the possibility
of static damage.
1.4.5 Analog Reference Pin (V_REFH)
The V_REFH pin is the analog reference voltage for the analog-to-digital converter (ADC) module. The
voltage is supplied through a double-bond to the V_DD pin. See Chapter 17 Electrical Specifications for
ADC parameters.
1.4.6 Port B Input/Output (I/O) Pins (PTB7/(OSC2)/RST–PTB0/AD0)
PTB7/(OSC2)/RST–PTB0/AD0 are general-purpose bidirectional I/O port pins, all sharing special
functions.
• PTB7 and PTB6 share with the on-chip oscillator circuit through configuration options. See 7.3.3
External Clock Generator.
• PTB5 and PTB4 share with the SCI module. See Chapter 12 Serial Communications Interface
Module (SCI).
• PTB3–PTB0 share with the ADC module. See Chapter 3 Analog-to-Digital Converter (ADC).
MC68HC908KX8 • MC68HC908KX2 • MC68HC08KX8 Data Sheet, Rev. 2.1
Freescale Semiconductor
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