Datasheet

MC68HC908QY4•MC68HC908QT4•MC68HC908QY2•MC68HC908QT2•MC68HC908QY1•MC68HC908QT1
MOTOROLA Input/Output (I/O) Ports 161
NON-DISCLOSURE AGREEMENT REQUIRED
Data Sheet — MC68HC908QY4
Section 12. Input/Output (I/O) Ports
12.1 Contents
12.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .161
12.3 Port A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .162
12.3.1 Port A Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . .163
12.3.2 Data Direction Register A. . . . . . . . . . . . . . . . . . . . . . . . . .164
12.3.3 Port A Input Pullup Enable Register. . . . . . . . . . . . . . . . . .166
12.4 Port B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .167
12.4.1 Port B Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . .167
12.4.2 Data Direction Register B. . . . . . . . . . . . . . . . . . . . . . . . . .168
12.4.3 Port B Input Pullup Enable Register. . . . . . . . . . . . . . . . . .169
12.2 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.
NOTE: Connect any unused I/O pins to an appropriate logic level, either V
DD
or
V
SS
. Although the I/O ports do not require termination for proper
operation, termination reduces excess current consumption and the
possibility of electrostatic damage.
Figure 12-1 provides a summary of the I/O registers.