![](http://datasheet.mmic.net.cn/Freescale-Semiconductor/MC68F375MZP33R2_datasheet_98733/MC68F375MZP33R2_169.png)
MC68F375
SINGLE-CHIP INTEGRATION MODULE 2 (SCIM2E)
MOTOROLA
REFERENCE MANUAL
Rev. 25 June 03
4-87
4.10 General-Purpose Input/Output
The SCIM2E has six general-purpose input/output ports: A, B, E, F, G, and H. (Port C,
an output-only port, is included under the discussion of chip-selects). Ports A, B, and
G are available in single-chip mode only and port H is available in single-chip and 8-
bit expanded modes only. Ports E, F, G, and H have associated data direction regis-
ters to configure each port pin as an input or output. Ports A and B share a data
direction register that configures each port entirely as inputs or outputs. Ports E and F
have associated pin assignment registers that allow the digital I/O or alternate function
of each port pin to be selected. Port F has an edge-detect flag register that indicates
whether a transition has occurred on any of its pins.
Table 4-42 shows the shared functions of the general-purpose I/O ports and the
modes in which they are available.
Access to the port A, B, E, G, and H data and data direction registers, and the port E
pin assignment register require three clock cycles to ensure timing compatibility with
external port replacement logic. Accesses to the port F registers require two clock
cycles. Port registers are byte-addressable and are grouped to allow coherent word
access to port data register pairs A-B and G-H, as well as word aligned long-word
coherency of the port A-B-G-H data registers.
Table 4-41 CSBOOT Base and Option Register
Reset Values
Fields
Reset Values
Base address
0x000000
Block size
1 Mbyte
Async/sync mode
Asynchronous mode
Upper/lower byte
Both bytes
Read/write
AS/DS
AS
DSACK
13 wait states
Address space
Supervisor space
IPL
Any level
Autovector
External vector externally
Table 4-42 General-Purpose I/O Ports
Port
Shared Function
Modes
A
ADDR[18:11]
Single-chip
B
ADDR[10:3]
Single-chip
E
Bus control signals
All
FIRQ[7:1]/FASTREF
All
G
DATA[15:8]
Single-chip
H
DATA[7:0]
Single-chip, 8-bit expanded
F
re
e
sc
a
le
S
e
m
ic
o
n
d
u
c
to
r,
I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
n
c
..
.