S912XEG384J3VA Datasheet, PDF (197/1324 Pages) Freescale Semiconductor, Inc – MC9S12XEP100 Reference Manual Covers MC9S12XE Family

3.3.2.3
Global Page Index Register (GPAGE)
Chapter 3 Memory Mapping Control (S12XMMCV4)
Address: 0x0010
7
R
0
W
6
GP6
5
GP5
4
GP4
Reset
0
0
0
0
= Unimplemented or Reserved
3
GP3
0
2
GP2
0
1
GP1
0
0
GP0
0
Figure 3-6. Global Page Index Register (GPAGE)
Read: Anytime
Write: Anytime
The global page index register is used to construct a 23 bit address in the global map format. It is only used
when the CPU is executing a global instruction (GLDAA, GLDAB, GLDD, GLDS, GLDX,
GLDY,GSTAA, GSTAB, GSTD, GSTS, GSTX, GSTY) (see CPU Block Guide). The generated global
address is the result of concatenation of the CPU local address [15:0] with the GPAGE register [22:16] (see
Figure 3-7).
CAUTION
XGATE write access to this register during an CPU access which makes use
of this register could lead to unexpected results.
Global Address [22:0]
Bit22
Bit16 Bit15
Bit 0
GPAGE Register [6:0]
CPU Address [15:0]
Figure 3-7. GPAGE Address Mapping
Field
6–0
GP[6:0]
Table 3-9. GPAGE Field Descriptions
Description
Global Page Index Bits 6–0 — These page index bits are used to select which of the 128 64-kilobyte pages is
to be accessed.
Example 3-1. This example demonstrates usage of the GPAGE register
LDX
MOVB
GLDAA
#0x5000
#0x14, GPAGE
X
;Set GPAGE offset to the value of 0x5000
;Initialize GPAGE register with the value of 0x14
;Load Accu A from the global address 0x14_5000
MC9S12XE-Family Reference Manual Rev. 1.25
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