Datasheet

Chapter 3 Memory Mapping Control (S12XMMCV4)
MC9S12XE-Family Reference Manual Rev. 1.25
222 Freescale Semiconductor
Figure 3-24. ROM in Single Chip Modes
3.5.3.2 ROM Control in Emulation Single-Chip Mode
In emulation single-chip mode the external bus is connected to the emulator. If the EROMON bit is set,
the internal FLASH provides the data and the emulator can observe all internal CPU actions on the external
bus. If the EROMON bit is cleared, the emulator provides the data (generator) and traces the all CPU
actions (see Figure 3-25).
Figure 3-25. ROM in Emulation Single-Chip Mode
3.5.3.3 ROM Control in Normal Expanded Mode
In normal expanded mode the external bus will be connected to the application. If the ROMON bit is set,
the internal FLASH provides the data. If the ROMON bit is cleared, the application memory provides the
data (see Figure 3-26).
MCU
Flash
No External Bus
EROMON = 1
Emulator
MCU
EROMON = 0
Emulator
Flash
MCU
Flash
Observer
Generator