PXD20RM Datasheet, PDF (79/1628 Pages) Freescale Semiconductor, Inc – PXD20 Microcontroller

The MMU translates physical memory addresses for use by the CPU and it must be configured before any
peripherals or memories are available for use by the CPU. See the e200z4 Power Architecture Core
Reference Manual for details on how to configure the MMU.
The MC_ME module enables the modules and other features like clocks. It is therefore an essential part
of the initialization and operation software. In general, the software will configure an MC_ME mode to
make certain peripherals, clocks, and memory active and then switch to that mode.
Chapter 8, Clock Description, includes a graphic of the clock architecture of the MCU. This can be used
to determine how to configure the MC_CGM module. In general software will configure the module to
enable the required clocks and PLLs and route these to the active modules.
After these steps are complete it is possible to configure the input/output pins and the modules for the
application.
1.7.4 Other features
The MC_ME module manages low power modes and so it is likely that it will be used to switch into
different configurations (module sets, clocks) depending on the application requirements.
The MCU includes two other features (both described in Chapter 4, Safety) to improve the integrity of the
application:
• It is possible to enable a software watchdog (SWT) immediately at reset or afterwards to help
detect code runaway.
• Individual register settings can be protected from unintended writes using the features of the
Register Protection module. The protected registers are shown in Appendix A, Registers Under
Protection.
Other integration functionality is provided by the System Status and Configuration Module (SSCM).
Freescale Semiconductor
PXD20 Microcontroller Reference Manual, Rev. 1
Preliminary—Subject to Change Without Notice
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