Chapter 5 External Bus Interface (S12XEBIV4)
MC9S12XE-Family Reference Manual , Rev. 1.19
244
Freescale Semiconductor
Table 5-2. External System Signals Associated with XEBI
Signal
I
(1)
/O
1. All inputs are capable of reducing input threshold level
EBI Signal
Multiplex
(T)ime
(2)
(F)unction
(3)
2. Time-multiplex means that the respective signals share the same pin on chip level and are active alternating in a dedicated
time slot (in modes where applicable).
3. Function-multiplex means that one of the respective signals sharing the same pin on chip level continuously uses the pin
depending on configuration and reset state.
Description
Available in Modes
NS
SS
NX
ES
EX
ST
RE
O
—
—
Read Enable, indicates external read access
No
No
Yes
No
No
No
ADDR[22:20]
O
T
—
External address
No
No
Yes
Yes
Yes
Yes
ACC[2:0]
O
—
Access source
No
No
No
Yes
Yes
Yes
ADDR[19:16]
O
T
—
External address
No
No
Yes
Yes
Yes
Yes
IQSTAT[3:0]
O
—
Instruction Queue Status
No
No
No
Yes
Yes
Yes
ADDR[15:1]
O
T
—
External address
No
No
Yes
Yes
Yes
Yes
IVD[15:1]
O
—
Internal visibility read data
No
No
No
Yes
Yes
Yes
ADDR0
O
T
F
External address
No
No
No
Yes
Yes
Yes
IVD0
O
Internal visibility read data
No
No
No
Yes
Yes
Yes
UDS
O
—
Upper Data Select, indicates external access
to the high byte DATA[15:8]
No
No
Yes
No
No
No
LSTRB
O
—
F
Low Strobe, indicates valid data on DATA[7:0]
No
No
No
Yes
Yes
Yes
LDS
O
—
Lower Data Select, indicates external access
to the low byte DATA[7:0]
No
No
Yes
No
No
No
RW
O
—
F
Read/Write, indicates the direction of internal
data transfers
No
No
No
Yes
Yes
Yes
WE
O
—
Write Enable, indicates external write access
No
No
Yes
No
No
No
CS[3:0]
O
—
—
Chip select
No
No
Yes
No
Yes
No
DATA[15:8]
I/O
—
—
Bidirectional data (even address)
No
No
Yes
Yes
Yes
Yes
DATA[7:0]
I/O
—
—
Bidirectional data (odd address)
No
No
Yes
Yes
Yes
Yes
EWAIT
I
—
—
External control for external bus access
stretches (adding wait states)
No
No
Yes
No
Yes
No
Because
of
an
order
from
the
United
States
International
Trade
Commission,
BGA-packaged
product
lines
and
part
numbers
indicated
here
currently
are
not
available
from
Freescale
for
import
or
sale
in
the
United
States
prior
to
September
2010:
S12XE
products
in
208
MAPBGA
packages