mc9s12xd256 Freescale Semiconductor, Inc, mc9s12xd256 Datasheet - Page 622

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

Chapter 17 Memory Mapping Control (S12XMMCV2)
17.3.2.4
Read: Anytime
Write: anytime in special modes, one time only in other modes.
This register determines the position of the direct page within the memory map.
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
622
Address: 0x0011
Example 17-2. This example demonstrates usage of the Direct Addressing Mode by a global instruction
DP[15:8]
Reset
Field
7–0
W
R
Expansion of the CPU Local Address
LDAADR
MOVB
MOVB
GLDAA
DP15
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
EQU $0000
#$80,DIRECT
#$14,GPAGE
<LDAADR
DP14
0
6
Figure 17-9. DIRECT Address Mapping
Table 17-8. DIRECT Field Descriptions
Figure 17-8. Direct Register (DIRECT)
Bit16
MC9S12XDP512 Data Sheet, Rev. 2.17
Global Address [22:0]
DP13
0
5
;Initialize LDADDR with the value of $0000
;Initialize DIRECT register with the value of $80
;Initialize GPAGE register with the value of $14
;Load Accu A from the global address $14_8000
Bit15
CAUTION
Map).
DP12
DP [15:8]
0
4
Description
CPU Address [15:0]
Bit8
DP11
0
3
Bit7
DP10
0
2
Figure
Freescale Semiconductor
Bit0
DP9
1-9).
0
1
DP8
0
0