Memory Mapping Control (S12XMMCV4)
S12XS Family Reference Manual, Rev. 1.13
134
Freescale Semiconductor
3.3.2.3
Direct Page Register (DIRECT)
Read: Anytime
Write: anytime in special modes, one time only in other modes.
This register determines the position of the 256B direct page within the memory map.It is valid for both
global and local mapping scheme.
Figure 3-9. DIRECT Address Mapping
Bits [22:16] of the global address will be formed by the GPAGE[6:0] bits in case the CPU executes a global
instruction in direct addressing mode or by the appropriate local address to the global address expansion
(refer to
Section 3.4.2.1.1, “Expansion of the Local Address Map
Example 3-2. This example demonstrates usage of the Direct Addressing Mode
MOVB
#0x80,DIRECT
;Set DIRECT register to 0x80. Write once only.
;Global data accesses to the range 0xXX_80XX can be direct.
;Logical data accesses to the range 0x80XX are direct.
LDY
<00
;Load the Y index register from 0x8000 (direct access).
;< operator forces direct access on some assemblers but in
;many cases assemblers are “direct page aware” and can
;automatically select direct mode.
Address: 0x0011
7
6
5
4
3
2
1
0
R
DP15
DP14
DP13
DP12
DP11
DP10
DP9
DP8
W
Reset
0
0
0
0
0
0
0
0
Figure 3-8. Direct Register (DIRECT)
Table 3-5. DIRECT Field Descriptions
Field
Description
7–0
DP[15:8]
Direct Page Index Bits 15–8 — These bits are used by the CPU when performing accesses using the direct
addressing mode. The bits from this register form bits [15:8] of the address (see
Bit15
Bit0
Bit7
Bit22
CPU Address [15:0]
Global Address [22:0]
Bit8
Bit16
DP [15:8]
Содержание MC9S12XS128
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Страница 150: ...Memory Mapping Control S12XMMCV4 S12XS Family Reference Manual Rev 1 13 150 Freescale Semiconductor ...
Страница 168: ...Interrupt S12XINTV2 S12XS Family Reference Manual Rev 1 13 168 Freescale Semiconductor ...
Страница 194: ...Background Debug Module S12XBDMV2 S12XS Family Reference Manual Rev 1 13 194 Freescale Semiconductor ...
Страница 364: ...Periodic Interrupt Timer S12PIT24B4CV1 S12XS Family Reference Manual Rev 1 13 364 Freescale Semiconductor ...
Страница 396: ...Pulse Width Modulator S12PWM8B8CV1 S12XS Family Reference Manual Rev 1 13 396 Freescale Semiconductor ...
Страница 506: ...Voltage Regulator S12VREGL3V3V1 S12XS Family Reference Manual Rev 1 13 506 Freescale Semiconductor ...
Страница 736: ...Ordering Information S12XS Family Reference Manual Rev 1 13 736 Freescale Semiconductor ...
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