XC2000 datasheet(77/647 Pages) INFINEON

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XC2000 Derivatives

System Units (Vol. 1 of 2)

Memory Organization

Preliminary

User’s Manual

3-15

V1.0, 2007-06

MemoryX2K, V1.1

3.6

IO Areas

The following areas of the XC2000’s address space are marked as IO area:

•The external IO area is provided for external peripherals (or memories) and also

comprises the on-chip LXBus-peripherals, such as the CAN or USIC modules. It is

located from 20’0000H to 3F’FFFFH (2 Mbytes).

•The internal IO area provides access to the internal peripherals and is split into three

blocks:

– The SFR area, located from 00’FE00H to 00’FFFFH (512 bytes).

– The ESFR area, located from 00’F000H to 00’F1FFH (512 bytes).

– The XSFR area, located from 00’E000H to 00’EFFFH (4 Kbytes).

Note: The external IO area supports real byte accesses. The internal IO area does not

support real byte transfers, the complementary byte is cleared when writing to a

byte location.

The IO areas have special properties, because peripheral modules must be controlled

in a different way than memories:

•

Accesses are not buffered and cached, the write back buffers and caches are not

used to store IO read and write accesses.

•

Speculative reads are not executed, but delayed until all speculations are solved (e.g.

pre-fetching after conditional branches).

•

Data forwarding is disabled, an IO read access is delayed until all IO writes pending

in the pipeline are executed, because peripherals can change their internal state after

a write access.

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