INTRODUCTION
MOTOROLA
PORT B
5 - 3
5.1
INTRODUCTION
Port B is a dual-purpose I/O port. It performs as 15 general-purpose I/O (GPIO) pins,
each configurable as output or input, to be used for device control. Or, it can perform as
an 8-bit bidirectional host interface (HI) (see Figure 5-1), where it provides a convenient
connection to another processor. This section describes both configurations, including
examples of how to configure and use the port.
EXTERNAL ADDRESS
SWITCH
EXTERNAL DATA
SWITCH
BUS
CONTROL
HOST/DMA
PARALLEL
INTERFACE
SCI
INTERFACE
SSI
INTERFACE
PORT
A
I/0
(47)
PORT
C
I/0
(9)
PORT
B
I/0
(15)
A0 - A15
D0 - D23
PS
DS
X/Y
RD
WR
BN
BR
BG
WT
BS
—
—
—
—
—
—
—
—
—
—
—
—
PB0 - PB7
PB8
PB9
PB10
PB11
PB12
PB13
PB14
PC0
PC1
PC2
PC3
PC4
PC5
PC6
PC7
PC8
H0 - H7
HA0
HA1
HA2
HR/W
HEN
HREQ
HACK or PB14
RXD
TXD
SCLK
SC0
SC1
SC2
SCK
SRD
STD
DEFAULT
FUNCTION
ALTERNATE
FUNCTION
8
8
24
16
Figure 5-1 Port B Interface
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Freescale Semiconductor, Inc.
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