Memory interface – a summary
The Cortex®-M3 and Cortex-M4 processors possess the following memory system features:
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4GB straight line address space – With 32-bit addressing, the ARM® processors have access to as much as 4GB of storage. Even though many embedded systems don’t need greater than 1MB of memory, the 32-bit addressing capacity ensures future upgrade and expansion options. The Cortex-M3 and Cortex-M4 processors provide 32-bit buses utilizing a generic bus protocol known as AHB LITE. Public transit enables connections to 32/16/8-bit memory devices with appropriate memory interface controllers.
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Architecturally defined memory map – The 4GB storage is split into numerous regions for a number of predefined memory and peripheral uses. This enables the processor design to become enhanced for performance. For instance, the Cortex-M3 and Cortex-M4 processors have multiple bus interfaces to permit synchronised access in the CODE region for rule and knowledge operations to SRAM or peripheral regions.
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Support for little endian and large endian memory systems – The Cortex-M4 and Cortex-M4 processors could work with either little endian or big endian memory systems. Used, a microcontroller method is normally made with only one endian configuration.
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Bit band accesses (optional) – Once the bit-band feature is incorporated (based on microcontroller/System-on-Nick vendors), two 1MB regions within the memory map are bit addressable via two bit-band regions. This enables atomic use of individual bits in SRAM or peripheral address space.
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Write buffer – Whenever a write transfer to some bufferable memory region will require multiple cycles, the transfer could be buffered through the internal write buffer within the Cortex-M3 or Cortex-M4 processor so the processor could execute the following instruction, if at all possible. This enables greater program execution speed.
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Memory Protection Unit (Optional) – The MPU is really a programmable unit which defines access permissions for a number of memory regions. The MPU within the Cortex-M3 and Cortex-M4 processor supports eight programmable regions, and could be combined with an embedded OS to supply a robust system.
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Unaligned transfer support – All processors supporting ARMv7-M architecture (including Cortex-M3 and Cortex-M4 processors) support unaligned data transfers.
Resourse: https://sciencedirect.com/topics/engineering/
