mc9s12xd256 Freescale Semiconductor, Inc, mc9s12xd256 Datasheet - Page 666

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

Chapter 18 Memory Mapping Control (S12XMMCV3)
18.3.2.7
Read: Anytime
Write: Anytime
These eight index bits are used to page 1 KByte blocks into the EEPROM page window located in the local
(CPU or BDM) memory map from address 0x0800 to address 0x0BFF (see
accessing up to 256 Kbytes of EEPROM (in the Global map) within the 64 KByte Local map. The
EEPROM page index register is effectively used to construct paged EEPROM addresses in the Local map
format.
The reset value of 0xFE ensures that there is a linear EEPROM space available between addresses 0x0800
and 0x0FFF out of reset.
The fixed 1K page 0x0C00–0x0FFF of EEPROM is equivalent to page 255 (page number 0xFF).
666
Address: 0x0017
Reset
EP[7:0]
Field
7–0
W
R
EP7
0
EEPROM Page Index Bits 7–0 — These page index bits are used to select which of the 256 EEPROM array
pages is to be accessed in the EEPROM Page Window.
EEPROM Page Index Register (EPAGE)
1
7
XGATE write access to this register during an CPU access which makes use
of this register could lead to unexpected results.
0
1
EP6
1
6
Figure 18-13. EEPROM Page Index Register (EPAGE)
0
Figure 18-14. EPAGE Address Mapping
Table 18-13. EPAGE Field Descriptions
MC9S12XDP512 Data Sheet, Rev. 2.17
0
EP5
1
5
Bit17
Global Address [22:0]
EPAGE Register [7:0]
Bit16
CAUTION
EP4
1
4
Description
EP3
1
3
Bit10
Address: CPU Local Address
Bit9
EP2
or BDM Local Address
1
2
Figure
Address [9:0]
18-14). This supports
Freescale Semiconductor
EP1
1
1
Bit0
EP0
0
0