MC9S08GB32 Motorola, MC9S08GB32 Datasheet - Page 77

• Manufacturer Part Number: MC9S08GB32
• Description: Microcontrollers
• Manufacturer: Motorola

Chapter 6 Parallel Input/Output
6.1
This section explains software controls related to parallel input/output (I/O). The MC9S08GBxx has seven
I/O ports which include a total of 56 general-purpose I/O pins (one of these pins is output only). The
MC9S08GTxx has six I/O ports which include a total of up to 39 general-purpose I/O pins, depending on
the package (one pin, PTG0, is output only). See
about the logic and hardware aspects of these pins.
Many of these pins are shared with on-chip peripherals such as timer systems, external interrupts, or
keyboard interrupts. When these other modules are not controlling the port pins, they revert to
general-purpose I/O control. For each I/O pin, a port data bit provides access to input (read) and output
(write) data, a data direction bit controls the direction of the pin, and a pullup enable bit enables an internal
pullup device (provided the pin is configured as an input), and a slew rate control bit controls the rise and
fall times of the pins.
Freescale Semiconductor
Introduction
Not all general-purpose I/O pins are available on all packages. To avoid
extra current drain from floating input pins, the user’s reset initialization
routine in the application program should either enable on-chip pullup
devices or change the direction of unconnected pins to outputs so the pins
do not float.
MC9S08GB/GT Data Sheet, Rev. 2.3
Chapter 2, “Pins and
NOTE
Connections,” for more information
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