Table of Contents
Advertisement
4.5
I/O Transfer Function
4.5.1
I/O Function
The I/O transfer to or from the CompactFlash
Memory Card can be either 8 or 16 bits. When a
16-bit accessible port is addressed, the signal
-IOIS16 is asserted by the CompactFlash Card.
Otherwise, the -IOIS16 signal is de-asserted.
When a 16 bit transfer is attempted, and the
-IOIS16
signal
is
CompactFlash Card, the system must generate a
pair of 8-bit references to access the word's even
Table 4-15 I/O Function
Function Code
Standby Mode
Byte Input Access
(8 bits)
Byte Output
A c c e s s
(8 bits)
Word Input
A c c e s s
(16 bits)
Word Output
A c c e s s
(16 bits)
I/O Read Inhibit
I/O Write Inhibit
High Byte Input
Only
(8 bits)
High Byte Output
Only
(8 bits)
SanDisk CompactFlash Memory Card Product Manual © 1998 SANDISK CORPORATION
CompactFlash Memory Card Product Manual
not
asserted
by
the
-REG
-CE2
-CE1
X
H
H
L
H
L
L
H
L
L
H
L
L
H
L
L
L
L
L
L
L
H
X
X
H
X
X
L
L
H
L
L
H
byte and odd byte. The CompactFlash Card
permits both 8 and 16 bit accesses to all of its I/O
addresses, so -IOIS16 is asserted for all addresses
to which the CompactFlash Card responds.
The CompactFlash Memory Card may request the
host to extend the length of an input cycle until
data is ready by asserting the -WAIT signal at
the start of the cycle.
A0
- I O R D
- I O W R
X
X
X
L
L
H
H
L
H
L
H
L
H
H
L
L
L
H
L
H
L
X
L
H
X
H
L
X
L
H
X
H
L
D15-D8
D7-D0
High Z
High Z
High Z
Even-Byte
High Z
Odd-Byte
Don't Care
Even-Byte
Don't Care
Odd-Byte
Odd-Byte
Even-Byte
Odd-Byte
Even-Byte
Don't Care
Don't Care
High Z
High Z
Odd-Byte
High Z
Odd-Byte
Don't Care
43
Advertisement
Table of Contents
