Memory Controller

6.8.316-Bit PC Card Overview

The PXA255 processor 16-bit PC Card interface provides control for one 16-bit PC Card card slot with a PSKTSEL pin for support of a second slot. The PXA255 processor interface supports 8- and 16-bit peripherals and handles common memory, I/O, and attribute-memory accesses. The duration of each access is based on the values programmed in the fields in the MCMEMx, MCATTx, and MCIOx registers. Figure 6-26shows the memory map for the 16-bit PC Card space.

Figure 6-26. 16-Bit PC Card Memory Map

0x3C00_0000

0x3800_0000

0x3400_0000

0x3000_0000

0x2C00_0000

0x2800_0000

0x2400_0000

0x2000_0000

Socket 1 Common Memory Space

Socket 1 Attribute Memory Space

reserved

Socket 1 I/O Space

Socket 0 Common Memory Space

Socket 0 Attribute Memory Space

reserved

Socket 0 I/O Space

The 16-bit PC Card Memory Map space is divided into eight partitions, four for each card slot. The four partitions for each card slot are: common memory, I/O, attribute memory, and a reserved space. Each partition starts on a 64-Mbyte boundary.

During an access, pins MA[25:0], nPREG, and PSKTSEL are driven at the same time. nPCE1 and nPCE2 are driven concurrently with the address signals for common memory and attribute- memory accesses. For I/O accesses, their value depends on the value of nIOIS16 and is valid a fixed amount of time after nIOIS16 is valid.

Common memory and attribute memory accesses assert the nPOE or nPWE control signals. I/O accesses assert the nIOR or nIOW control signals and use the nIOIS16 input signal to determine the bus width of the transfer (8 or 16 bits). The PXA255 processor uses nPCE2 to indicate to the expansion device that the upper half of the data bus (MD[15:8]) are used for the transfer, and nPCE1 to indicate that the lower half of the data bus (MD[7:0]) are used. nPCE1 and nPCE2 are asserted for 16-bit accesses.

Refer to Table 6-31through Table 6-38for signal combinations during common memory, I/O, and attribute accesses.

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Intel® PXA255 Processor Developer’s Manual

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Intel PXA255 manual 3 16-Bit PC Card Overview, Bit PC Card Memory Map