System Memory Protection Unit (Smpu); Overview; Block Diagram - STMicroelectronics SPC572L series Reference Manual

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System Memory Protection Unit (SMPU)

16.1

Overview

The System Memory Protection Unit (SMPU) provides hardware access control for system
bus memory references. The SMPU concurrently monitors and evaluates system bus
transactions using pre-programmed region descriptors that define memory spaces and their
access rights. Memory references that have sufficient access control rights are allowed to
complete, while references that are not mapped to any region descriptor or have insufficient
rights are terminated with an access error response.
16.2

Block diagram

A simplified block diagram of the SMPU module is shown in the following figure. The
hardware's two-dimensional connection matrix is clearly visible with the basic access
evaluation macro shown as the replicated submodule block. The crossbar switch slave
ports are shown on the left, the region descriptor registers are in the middle, and the
peripheral bus interface is on the right side. The evaluation macro contains two magnitude
comparators connected to the start and end address registers from each region descriptor
as well as the combinational logic blocks to determine the region hit and detect protection
violations.
For details of the access evaluation macro, see
System Memory Protection Unit (SMPU)
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