XC866 datasheet(21/108 Pages) INFINEON

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XC866

Functional Description

Data Sheet

V1.0, 2006-02

3.2.2.2

Address Extension by Paging

Address extension is further performed at the module level by paging. With the address

extension by mapping, the XC866 has a 256-SFR address range. However, this is still

less than the total number of SFRs needed by the on-chip peripherals. To meet this

requirement, some peripherals have a built-in local address extension mechanism for

increasing the number of addressable SFRs. The extended address range is not directly

controlled by the CPU instruction itself, but is derived from bit field PAGE in the module

page register MOD_PAGE. Hence, the bit field PAGE must be programmed before

accessing the SFR of the target module. Each module may contain a different number

of pages and a different number of SFRs per page, depending on the specific

requirement. Besides setting the correct RMAP bit value to select the SFR area, the user

must also ensure that a valid PAGE is selected to target the desired SFR. A page inside

the extended address range can be selected as shown in Figure 8.

Figure 8

Address Extension by Paging

SFR0

SFR1

SFRx

PAGE 0

SFR0

SFR1

SFRy

PAGE 1

SFR0

SFR1

SFRz

PAGE q

MOD_PAGE.PAGE

SFR Address

(from CPU)

SFR Data

(to/from CPU)

Module

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