
Chapter 17 Memory Mapping Control (S12XMMCV2)
MC9S12XDP512 Data Sheet, Rev. 2.21
624
Freescale Semiconductor
17.3.2.6
RAM Page Index Register (RPAGE)
Read: Anytime
Write: Anytime
The RAM page index register allows accessing up to (1M minus 2K) bytes of RAM in the global memory
map by using the eight page index bits to page 4 Kbyte blocks into the RAM page window located in the
CPU local memory map from address $1000 to address $1FFF (see Figure 1-12).
CAUTION
XGATE write access to this register during an CPU access which makes use
of this register could lead to unexpected results.
Table 17-10. Data Sources when CPU or BDM is Accessing Flash Area
Chip Modes
ROMON
EROMON
DATA SOURCE1
1 Internal means resources inside the MCU are read/written.
Internal Flash means Flash resources inside the MCU are read/written.
Emulation memory means resources inside the emulator are read/written (PRU registers, ash
replacement, RAM, EEPROM and register space are always considered internal).
External application means resources residing outside the MCU are read/written.
Stretch2
2 The external access stretch mechanism is part of the EBI module (refer to EBI Block Guide for details).
Normal Single Chip
X
Internal
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
Internal Flash
Special Test
0
X
External Application
N
1
X
Internal Flash
Address: 0x0016
76543210
R
RP7
RP6
RP5
RP4
RP3
RP2
RP1
RP0
W
Reset
11111101
Figure 17-11. RAM Page Index Register (RPAGE)