Datasheet

MC9S08AW60 Data Sheet, Rev 2
Freescale Semiconductor 81
Chapter 6
Parallel Input/Output
6.1 Introduction
This chapter explains software controls related to parallel input/output (I/O). The MC9S08AW60 has
seven I/O ports which include a total of 54 general-purpose I/O pins. 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, communication systems, or
keyboard interrupts. When these other modules are not controlling the port pins, they revert to
general-purpose I/O control.
Pins that are not used in the application must be terminated. This prevents excess current caused by floating
inputs and enhances immunity during noise or transient events. Termination methods include:
• Configuring unused pins as outputs driving high or low
• Configuring unused pins as inputs and using internal or external pullups
Never connect unused pins to V
DD
or V
SS
.
6.2 Features
Parallel I/O and Pin Control features, depending on package choice, include:
• A total of 54 general-purpose I/O pins in seven ports
• Hysteresis input buffers
• Software-controlled pullups on each input pin
Table 6-1. KBI and Parallel I/O Interaction
PTxPEn
(Pull Enable)
PTxDDn
(Data Direction)
KBIPEn
(KBI Pin Enable)
KBEDGn
(KBI Edge Select)
Pullup Pulldown
000 x
1
1
x = Don’t care
disabled disabled
1 0 0 x enabled disabled
x 1 0 x disabled disabled
1 x 1 0 enabled disabled
1 x 1 1 disabled enabled
0 x 1 x disabled disabled