
SCF5250 Data Sheet: Technical Data, Rev. 1.3
Freescale Semiconductor
9
Table 2. SCF5250 Signal Index
Signal Name
Mnemonic
Function
Input/
Output
Reset
State
Address
A[24:1]
A[23]/GPO54
24 address lines, address line 23
multiplexed with GPO54 and address 24
is multiplexed with A20 (SDRAM access
only).
Out
X
Read-write control
R/W
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/GPIO59
Row address strobe for external SDRAM.
Out
negated
Synchronous column
address strobe
SDCAS/GPIO39
Column address strobe for external
SDRAM
Out
negated
SDRAM write enable
SDWE/GPIO38
Write enable for external SDRAM
Out
negated
SDRAM upper byte
enable
SDUDQM/GPO53
Indicates during write cycle if high byte is
written
Out
–
SDRAM lower byte enable SDLDQM/GPO52
Indicates during write cycle if low byte is
written
Out
–
SDRAM chip selects
SD_CS0/GPIO60
SDRAM chip select
In/Out negated
SDRAM clock enable
BCLKE/GPIO63
SDRAM clock enable
Out
–
System clock
BCLK/GPIO40
SDRAM clock output
In/Out
–
ISA bus read strobe
IDE-DIOR/GPIO31
(CS2)
There is 1 ISA bus read strobe and 1 ISA
bus write strobe. They allow connection
of one independent ISA bus peripherals,
e.g. an IDE slave device.
In/Out
–
ISA bus write strobe
IDE-DIOW/GPIO32
(CS2)
In/Out
–
ISA bus wait signal
IDE-IORDY/GPIO33
ISA bus wait line - available for both
busses
In/Out
–
Chip Selects[2:0]
CS0/CS4
CS1/QSPI_CS3/GPIO28
Enables peripherals at programmed
addresses.
CS[0] provides boot ROM selection
Out
In/Out
negated
Buffer enable 1
BUFENB1/GPIO29
Two programmable buffer enables allow
seamless steering of external buffers to
split data and address bus in sections.
In/Out
–
Buffer enable 2
BUFENB2/GPIO30
In/Out
–
Transfer acknowledge
TA/GPIO12
Transfer Acknowledge signal
In/Out
–
Wake Up
WAKE_UP/GPIO21
Wake-up signal input
In
–
Serial Clock Line
SCL0/SDATA1_BS1/GPIO41
SCL1/TXD1/GPIO10
Clock signal for Dual I2C module
operation
In/Out
–
Serial Data Line
SDA0/SDATA3/GPIO42
SDA1/RXD1/GPIO44
Serial data port for second I2C module
operation
In/Out
–
Receive Data
SDA1/RXD1/GPIO44
RXD0/GPIO46
Signal is receive serial data input for
DUART
In
–