EM346-RTR datasheet(26/142 Pages) SILABS

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EM346

Rev 1.0

5. ARM® Cortex™-M3 and Memory Modules

This chapter discusses the ARM® CortexTM-M3 Microprocessor, and reviews the EM346’s flash and RAM memory

modules as well as the Memory Protection Unit (MPU).

5.1. ARM® Cortex™-M3 Microprocessor

The EM346 integrates the ARM® CortexTM-M3 microprocessor, revision r1p1, developed by ARM Ltd., making the

EM346 a true System-on-Chip solution. The ARM® CortexTM-M3 is an advanced 32-bit modified Harvard

architecture processor that has separate internal program and data buses, but presents a unified program and data

address space to software. The word width is 32 bits for both the program and data sides. The ARM® CortexTM-M3

allows unaligned word and half-word data accesses to support efficiently-packed data structures.

The ARM® CortexTM-M3 in the EM346 has also been enhanced to support two separate memory protection levels.

Basic protection is available without using the MPU, but normal operation uses the MPU. The MPU allows for

protecting unimplemented areas of the memory map to prevent common software bugs from interfering with

software operation. The architecture could also allow for separation of the networking stack from the application

code using a fine granularity RAM protection module. Errant writes are captured and details are reported to the

developer to assist in tracking down and fixing issues.

5.2. Embedded Memory

Figure 5.1 shows the EM346 ARM® CortexTM-M3 memory map.

EM346-RTR データシート(PDF) 26 Page - Silicon Laboratories