MC908QT1 FREESCALE [Freescale Semiconductor, Inc], MC908QT1 Datasheet - Page 97

• Manufacturer Part Number: MC908QT1
• Description: Microcontrollers
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

Chapter 12
Input/Output Ports (PORTS)
12.1 Introduction
The MC68HC908QT1, MC68HC908QT2, and MC68HC908QT4 have five bidirectional input-output (I/O)
pins and one input only pin. The MC68HC908QY1, MC68HC908QY2, and MC68HC908QY4 have
thirteen bidirectional pins and one input only pin. All I/O pins are programmable as inputs or outputs.
12.2 Port A
Port A is a 6-bit special function port that shares all six of its pins with the keyboard interrupt (KBI) module
(see
device if the corresponding port pin is configured as an input port.
Freescale Semiconductor
Chapter 9 Keyboard Interrupt Module
Connect any unused I/O pins to an appropriate logic level, either V
Although the I/O ports do not require termination for proper operation,
termination reduces excess current consumption and the possibility of
electrostatic damage.
8-pin devices have non-bonded pins. These pins should be configured
either as outputs driving low or high, or as inputs with internal pullups
enabled. Configuring these non-bonded pins in this manner will prevent any
excess current consumption caused by floating inputs.
PTA2 is input only.
When the IRQ function is enabled in the configuration register 2
(CONFIG2), bit 2 of the port A data register (PTA) will always read a 0. In
this case, the BIH and BIL instructions can be used to read the logic level
on the PTA2 pin. When the IRQ function is disabled, these instructions will
behave as if the PTA2 pin is a logic 1. However, reading bit 2 of PTA will
read the actual logic level on the pin.
MC68HC908QY/QT Family Data Sheet, Rev. 5
(KBI)). Each port A pin also has a software configurable pullup
NOTE
NOTE
DD
or V
SS
.
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