
MOTOROLA
Signal Description
2-1
Section 2
Signal Description
2.1
INTRODUCTION
This section describes the MCF5249 input and output signals. The signal descriptions as shown in
Table2-1 are grouped according to relevant functionality.
Table 2-1 MCF5249 Signal Index
SIGNAL NAME
MNEMONIC
FUNCTION
INPUT/
OUTPUT
RESET
STATE
Address
A[23:1]
A[25]/GPO8
23 address bus lines, address line 25
multiplexed with gpo8
Out
X
Read-write control
RW_b
Bus write enable - indicates if read or
write cycle in progress
Out
H
Output enable
OE
Output enable for asynchronous
memories connected to chip selects
Out
negated
Data
D[31:16]
Data bus used to transfer word data
In/Out
Hi-Z
Synchronous row address
strobe
SDRAS
Row address strobe for external
SDRAM.
Out
negated
Synchronous column
address strobe
SDCAS
Column address strobe for external
SDRAM
Out
negated
SDRAM write enable
SDWE
Write enable for external SDRAM
Out
negated
SDRAM upper byte
enable
SDUDQM
Indicates during write cycle if high
byte is written
Out
SDRAM lower byte enable SDLDQM
Indicates during write cycle if low
byte is written
Out
SDRAM chip selects
SDRAMCS1
SDRAM chip select
Out
negated
SDRAM chip selects
SDRAMCS2/GPIO7
SDRAM chip select
In/Out
negated
SDRAM clock enable
BCLKE
SDRAM clock enable
Out
System clock
SCLK/GPIO10
SDRAM clock output
In/Out
ISA bus read strobes
CS2/IDE-DIOR/GPIO13
CS3/SRE/GPIO11
There are 2 ISA bus read strobes
and 2 ISA bus write strobes. They
Allow connection of two independent
ISA bus peripherals, e.g. an IDE
slave device and a SmartMedia card
In/Out
ISA bus write strobes
IDE-DIOW/GPIO14
SWE/GPIO12
In/Out
ISA bus wait signal
IDE-IORDY/GPIO16
ISA bus wait line - available for both
busses
In/Out
Chip Selects[1:0]
CS0
CS1/GPIO58
Enables peripherals at programmed
addresses. CS[1:0]. CS[0] provides
boot ROM selection
Out
In/Out
negated
Buffer enable 1
BUFENB1/GPIO57
Two programmable buffer enables
Allow seamless steering of external
buffers to split data and address bus
in sections.
In/Out
Buffer enable 2
BUFENB2/GPIO7
In/Out
Transfer acknowledge
TA/GPIO20
Transfer Acknowledge signal
In/Out
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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