MC9S12Q FREESCALE [Freescale Semiconductor, Inc], MC9S12Q Datasheet - Page 103

• Manufacturer Part Number: MC9S12Q
• Description: Microcontrollers
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

2.4
Each pin can act as general purpose I/O. In addition the pin can act as an output from a peripheral module
or an input to a peripheral module.
A set of configuration registers is common to all ports. All registers can be written at any time, however a
specific configuration might not become active.
Example: Selecting a pull-up resistor. This resistor does not become active while the port is used as a push-
pull output.
2.4.1
2.4.1.1
This register holds the value driven out to the pin if the port is used as a general purpose I/O. Writing to
this register has only an effect on the pin if the port is used as general purpose output. When reading this
address, the value of the pins are returned if the data direction register bits are set to 0.
If the data direction register bits are set to 1, the contents of the I/O register is returned. This is independent
of any other configuration
2.4.1.2
This is a read-only register and always returns the value of the pin
2.4.1.3
This register defines whether the pin is used as an input or an output. If a peripheral module controls the
pin the contents of the data direction register is ignored
Freescale Semiconductor
Functional Description
Registers
I/O Register
Input Register
Data Direction Register
(Figure
Figure 2-46. Illustration of I/O Pin Functionality
Module
DDR
PTI
PT
2-46).
Data Out
Output Enable
Module Enable
0
1
MC9S12Q128
Rev 1.09
0
1
0
1
Chapter 2 Port Integration Module (PIM9C32) Block Description
(Figure
2-46).
(Figure
PAD
2-46).
103