SAF-XC888-6FFI 查看數據表（PDF） - Infineon Technologies

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SAF-XC888-6FFI

8-Bit Single-Chip Microcontroller

Infineon Technologies 

XC886/888CLM

Functional Description

3.2.2 Special Function Register

The Special Function Registers (SFRs) occupy direct internal data memory space in the

range 80H to FFH. All registers, except the program counter, reside in the SFR area. The

SFRs include pointers and registers that provide an interface between the CPU and the

on-chip peripherals. As the 128-SFR range is less than the total number of registers

required, address extension mechanisms are required to increase the number of

addressable SFRs. The address extension mechanisms include:

• Mapping

• Paging

3.2.2.1 Address Extension by Mapping

Address extension is performed at the system level by mapping. The SFR area is

extended into two portions: the standard (non-mapped) SFR area and the mapped SFR

area. Each portion supports the same address range 80H to FFH, bringing the number

of addressable SFRs to 256. The extended address range is not directly controlled by

the CPU instruction itself, but is derived from bit RMAP in the system control register

SYSCON0 at address 8FH. To access SFRs in the mapped area, bit RMAP in SFR

SYSCON0 must be set. Alternatively, the SFRs in the standard area can be accessed

by clearing bit RMAP. The SFR area can be selected as shown in Figure 8.

SYSCON0

System Control Register 0

Reset Value: 00H

7

6

5

4

3

2

1

0

0

IMODE

0

r

rw

r

RMAP

rw

The functions of the shaded bits are not described here

Field

RMAP

0

Bits

0

[7:5],

[3:1]

Type Description

rw Special Function Register Map Control

0 The access to the standard SFR area is

enabled.

1 The access to the mapped SFR area is

enabled.

r

Reserved

Returns 0 if read; should be written with 0.

Data Sheet

Prelimary

21

V0.1, 2006-02

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