Table 220. 16-Bit Pc-Card Signals And Access Type - ST STM32F40 Series Reference Manual

RM0090
the odd byte on D15-8 and nCE1 accesses the even byte on D7-0 if A0=0 or the odd byte on
D7-0 if A0=1. The full word is accessed on D15-0 if both nCE2 and nCE1 are low.
The memory space is selected by asserting low nOE for read accesses or nWE for write
accesses, combined with the low assertion of nCE2/nCE1 and nREG.
●
If pin nREG=1 during the memory access, the common memory space is selected
●
If pin nREG=0 during the memory access, the attribute memory space is selected
The I/O Space is selected by asserting low nIORD for read accesses or nIOWR for write
accesses [instead of nOE/nWE for memory Space], combined with nCE2/nCE1. Note that
nREG must also be asserted low during accesses to I/O Space.
Three type of accesses are allowed for a 16-bit PC Card:
●
Accesses to Common Memory Space for data storage can be either 8-bit accesses at
even addresses or 16 bit AHB accesses.
Note that 8-bit accesses at odd addresses are not supported and will not lead to the
low assertion of nCE2. A 32-bit AHB request is translated into two 16-bit memory
accesses.
●
Accesses to Attribute Memory Space where the PC Card stores configuration
information are limited to 8-bit AHB accesses at even addresses.
Note that a 16-bit AHB access will be converted into a single 8-bit memory transfer:
nCE1 will be asserted low, NCE2 will be asserted high and only the even Byte on D7-
D0 will be valid. Instead a 32-bit AHB access will be converted into two 8-bit memory
transfers at even addresses: nCE1 will be asserted low, NCE2 will be asserted high
and only the even bytes will be valid.
●
Accesses to I/O Space can be performed either through AHB 8-bit or 16-bit accesses.

Table 220. 16-bit PC-Card signals and access type

1 0 1 0
0 1 1 0
0 0 1 0
X 0 0 0
X 0 0 0
1 0 0 0
0 1 0 0
1 X X X-X X
1 X X X-X X
1 X X X-X 0
1 0 1 X-X 0
1 0 0 X-X 0
1 X X X-X 1
1 X X X-X x
Doc ID 018909 Rev 4
Flexible static memory controller (FSMC)
Space Access Type
Read/Write byte on D7-D0
Common
Memory Read/Write byte on D15-D8
Space
Read/Write word on D15-D0
Read or Write Configuration
Registers
Attribute
Space
Read or Write CIS (Card
Information Structure)
Invalid Read or Write (odd address)
Attribute
Read or Write (odd address)
Space
Allowed/not
Allowed
YES
Not supported
YES
YES
YES
YES
YES
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