mc9s12xd256 Freescale Semiconductor, Inc, mc9s12xd256 Datasheet - Page 662

• Manufacturer Part Number: mc9s12xd256
• Description: Hcs12x Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Chapter 18 Memory Mapping Control (S12XMMCV3)
18.3.2.4
Read: Anytime
Write: anytime in special modes, one time only in other modes.
This register determines the position of the 256 Byte direct page within the memory map.It is valid for both
global and local mapping scheme.
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
662
Address: 0x0011
DP[15:8]
Reset
Field
7–0
W
R
Section 18.4.2.1.1, “Expansion of the Local Address
MOVB
LDY
DP15
Example 18-2. This example demonstrates usage of the Direct Addressing Mode
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
Direct Page Register (DIRECT)
0
7
XGATE write access to this register during an CPU access which makes use
of this register could lead to unexpected results.
Bit22
#0x80,DIRECT
<00
DP14
0
6
Figure 18-9. DIRECT Address Mapping
Table 18-9. DIRECT Field Descriptions
Figure 18-8. Direct Register (DIRECT)
Bit16
MC9S12XDP512 Data Sheet, Rev. 2.17
Global Address [22:0]
DP13
0
5
;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.
;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
Bit15
CAUTION
DP12
DP [15:8]
0
4
Description
CPU Address [15:0]
Bit8
DP11
Map).
0
3
Bit7
DP10
0
2
Figure
Freescale Semiconductor
Bit0
DP9
18-9).
0
1
DP8
0
0