Atmel Xplained Evaluation Board AT32UC3A3-XPLD AT32UC3A3-XPLD Data Sheet

32072H–AVR32–10/2012

The External Bus Interface integrates circuitry that interfaces to CompactFlash devices.

The CompactFlash logic is driven by the SMC on the NCS[4] and/or NCS[5] address space.
Writing to the HMATRIX.SFR6.CS4A and/or HMATRIX.SFR6.CS5A bits the appropriate value
enables this logic.

 

Access to an external CompactFlash device is then made by accessing the

address space reserved to NCS[4] and/or NCS[5].

Attribute Memory, Common Memory, I/O modes are supported but the signals _IOWR, _IOIS16
(I/O mode) are not handled.

Within the NCS[4] and/or NCS[5] address space, the current transfer address is used to distin-
guish I/O mode, common memory mode andattribute memory mode.

The different modes are accessed through a specific memory mapping as illustrated on 

. ADDR[23:21] bits of the transfer address are used to select the desired mode

as described in 

Figure 14-2. CompactFlash Memory Mapping

Note:

The ADDR[22] I/O line is used to drive the REG signal of the CompactFlash Device.

To cover all types of access, the SMC must be alternatively set to drive 8-bit data bus or 16-bit
data bus. The odd byte access on the DATA[7:0] bus is only possible when the SMC is config-

CompactFlash Mode Selection

000

Attribute Memory

001

I/O Mode (Write operations)

010

Common Memory

100

I/O Mode (Read operations)

I/O Mode Space 

(Read operations)

Common Memory Mode Space

Attribute Memory Mode Space

Offset 0x0080 0000

Offset 0x0040 0000

Offset 0x0000 0000

CF Address Space

I/O Mode Space 

(Write operations)

Offset 0x0020 0000