PXS20RM Datasheet, PDF (1183/1368 Pages) Freescale Semiconductor, Inc – PXS20 Microcontroller

Chapter 40
Register Protection (REG_PROT)
Register Protection (REG_PROT)
40.1 Introduction
40.1.1 Overview
The REG_PROT module offers a mechanism to protect defined memory-mapped address locations in a
module under protection from being written. The address locations that can be protected are
module-specific.
The protection module is located between the module under protection and the PBRIDGE. (For an
explanation of the REG_PROT and module base addresses, see Section 40.3, Memory map and register
definition.) This is shown in Figure 40-1.
PBRIDGE
peripheral enable
REG_PROT module
Access allowed?
peripheral
enable
supervisor access /
address / access size
write data
Lock
Registers
Other control signals
UAA
GCR
HLB
Module
under
Protection
Figure 40-1. REG_PROT block diagram
40.1.2 Features
The REG_PROT includes these distinctive features:
• Restrict write accesses for the module under protection to supervisor mode only
• Lock registers for first 6 KB of memory-mapped address space
• Write to address mirror automatically sets corresponding lock bit
• Once configured lock bits can be protected from changes
Freescale Semiconductor
PXS20 Microcontroller Reference Manual, Rev. 1
40-1