Manual

220 Series Commercial Grade CF Product Manual v2.0Cactus Technologies
®
22
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 not
asserted by the CompactFlash Card, the system must generate a pair of 8-bit references to access
the word‘s even 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 (refer to Table 3-16).
I/O Transfer Function
3.5.
Table 3-16. I/O Function
Function Code -REG -CE2 -CE1 A0 -IORD -IOWR D15-D8 D7-D0
Standby Mode
X H H X X X High Z High Z
Byte Input Access
(8 bits)
L
L
H
H
L
L
L
H
L
L
H
H
High Z
High Z
Even-Byte
Odd-Byte
Byte Output Access
(8 bits)
L
L
H
H
L
L
L
H
H
H
L
L
Do not care
Do not care
Even-Byte
Odd-Byte
Word Input Access
(16 bits)
L L L L L H Odd-Byte Even-Byte
Word Output Access
(16 bits)
L L L L H L Odd-Byte Even-Byte
I/O Read Inhibit
H X X X L H Do not care Do not care
I/O Write Inhibit
H X X X H L High Z High Z
High Byte Input Only
(8 bits)
L L H X L H Odd-Byte High Z
High Byte Output
Only (8 bits)
L L H X H L Odd-Byte Do not care