P912XDP512F0MPVR datasheet(646/1348 Pages) FREESCALE

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Chapter 17 Memory Mapping Control (S12XMMCV2)

MC9S12XDP512 Data Sheet, Rev. 2.21

646

Freescale Semiconductor

17.5.3

On-Chip ROM Control

The MCU offers two modes to support emulation. In the ﬁrst mode (called generator) the emulator

provides the data instead of the internal FLASH and traces the CPU actions. In the other mode (called

observer) the internal FLASH provides the data and all internal actions are made visible to the emulator.

17.5.3.1

ROM Control in Single-Chip Modes

In single-chip modes the MCU has no external bus. All memory accesses and program fetches are internal

(see Figure 1-27).

Figure 17-27. ROM in Single Chip Modes

17.5.3.2

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 1-28).

Figure 17-28. ROM in Emulation Single-Chip Mode

MCU

Flash

No External Bus

EROMON = 1

Emulator

MCU

EROMON = 0

Emulator

Flash

MCU

Flash

Observer

Generator

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