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Chapter 3 Memory Mapping Control (S12XMMCV4)
MC9S12XE-Family Reference Manual Rev. 1.07
Freescale Semiconductor
197
3.3.2.6
Program Page Index Register (PPAGE)
Read: Anytime
Write: Anytime
These eight index bits are used to page 16 KByte blocks into the Flash page window located in the local
(CPU or BDM) memory map from address 0x8000 to address 0xBFFF (see
Figure 3-12
). This supports
accessingupto4MbytesofFlash(intheGlobalmap)withinthe64KByteLocalmap.ThePPAGEregister
iseffectivelyusedtoconstructpagedFlashaddressesintheLocalmapformat.TheCPUhasspecialaccess
to read and write this register directly during execution of CALL and RTC instructions..
CAUTION
XGATEwriteaccesstothisregisterduringanCPUaccesswhichmakesuse
of this register could lead to unexpected results.
Table 3-11. Data Sources when CPU or BDM is Accessing Flash Area
Chip Modes
ROMON
EROMON
DATA SOURCE
1
1
Internal Flash means Flash resources inside the MCU are read/written.
Emulation memory means resources inside the emulator are read/written (PRU registers, flash
replacement, RAM, EEPROM and register space are always considered internal).
External application means resources residing outside the MCU are read/written.
2
The external access stretch mechanism is part of the EBI module (refer to EBI Block Guide for details).
Stretch
2
Normal Single Chip
X
X
Internal Flash
N
Special Single Chip
Emulation Single Chip
X
0
Emulation Memory
N
X
1
Internal Flash
Normal Expanded
0
X
External Application
Y
1
X
Internal Flash
N
Emulation Expanded
0
X
External Application
Y
1
0
Emulation Memory
N
1
1
Internal Flash
Special Test
0
X
External Application
N
1
X
Internal Flash
Address: 0x0015
7
6
5
4
3
2
1
0
R
W
PIX7
PIX6
PIX5
PIX4
PIX3
PIX2
PIX1
PIX0
Reset
1
1
1
1
1
1
1
0
Figure 3-11. Program Page Index Register (PPAGE)