MC9S08RG60 Datasheet, PDF (111/232 Pages) Motorola, Inc – Microcontrollers

Chapter 8 Parallel Input/Output
SoC Guide — MC9S08RG60/D Rev 1.10
8.1 Introduction
This section explains software controls related to parallel input/output (I/O). The MC9S08RC/RD/RE/RG
has five I/O ports that include a total of 39 general-purpose I/O pins (two of these pins are output only and
one pin is input only). Not all of the ports are available in all packages. See Chapter 2 Pins and Connections
for more information 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 (if the pin is configured as an input).
NOTE:
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.
8.2 Features
Parallel I/O features for the MC9S08RC/RD/RE/RG MCUs, depending on specific device and package
choice, include:
• A total of 39 general-purpose I/O pins in five ports (two pins are output only, one is input only)
• High-current drivers on port B pins
• Hysteresis input buffers on all inputs
• Software-controlled pullups on each input pin
• Eight port A pins shared with KBI1
• Eight port B pins shared with SCI and TPMCH1
• Eight port C pins shared with KBI2 and SPI
• Seven port D pins shared with TPMCH0, ACMP, IRQ, RESET, and BKGD/MS
• Eight port E pins
8.3 Pin Descriptions
The MC9S08RC/RD/RE/RG has a total of 39 parallel I/O pins distributed between four 8-bit ports and one
7-bit port. Not all pins are bonded out in all packages. Consult the pin assignment in the Pins and
Connections section for available parallel I/O pins. All of these pins are available for general-purpose I/O
when they are not used by other on-chip peripheral systems.
Freescale Semiconductor
MC9S08RC/RD/RE/RG
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