saa-xc886clm Infineon Technologies Corporation, saa-xc886clm Datasheet - Page 27

• Manufacturer Part Number: saa-xc886clm
• Description: 8-bit Single Chip Microcontroller
• Manufacturer: Infineon Technologies Corporation

3.2.2
The Special Function Registers (SFRs) occupy direct internal data memory space in the
range 80
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:
•
•
3.2.2.1
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 80
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 8F
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
As long as bit RMAP is set, the mapped SFR area can be accessed. This bit is not
cleared automatically by hardware. Thus, before standard/mapped registers are
accessed, bit RMAP must be cleared/set, respectively, by software.
Data Sheet
Mapping
Paging
H
to FF
Special Function Register
Address Extension by Mapping
H
. All registers, except the program counter, reside in the SFR area. The
H
. To access SFRs in the mapped area, bit RMAP in SFR
20
H
to FF
H
Functional Description
, bringing the number of
Figure
SAA-XC886CLM
7.
V1.0, 2009-09