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Monday, March 10, 2014

Cortex M3 Processor

The ARM Cortex™-M3 processor is the industry-leading 32-bit processor for highly deterministic real-time applications, specifically developed to enable developers to develop high-performance low-cost platforms for a broad range of devices including microcontrollers, automotive body systems, industrial control systems and wireless networking and sensors. The processor delivers outstanding computational performance and exceptional system response to events while meeting the challenges of low dynamic and static power constraints. The processor is highly configurable enabling a wide range of implementations from those requiring memory protection and powerful trace technology to cost sensitive devices requiring minimal area.

Why Cortex-M3??

Delivering higher performance and richer features

Introduced in 2004 and recently updated with new technologies and configurability, the Cortex-M3 is the mainstream ARM processor developed specifically with microcontroller applications in mind.

Performance and Energy Efficiency 

With high performance and low dynamic power consumption the Cortex-M3 processor delivers leading power efficiency. Coupled with integrated sleep modes and optional state retention capabilities the Cortex-M3 processor ensures there is no compromise for applications requiring low power and excellent performance.

Full featured

The processor executes Thumb®-2 instruction set for optimal performance and code size, including hardware division, single cycle multiply, and bit-field manipulation. The Cortex-M3 NVIC is highly configurable at design time to deliver up to 240 system interrupts with individual priorities, dynamic reprioritization and integrated system clock.

Rich connectivity

The combination of features and performance enables Cortex-M3 based devices efficiently to handle multiple I/O channels and protocol standards such as USB OTG (On-The-Go). 

Energy efficiency advantage

The demand for ever lower-cost products with increasing connectivity (e.g. USB, Bluetooth, IEEE 802.15) and sophisticated analog sensors (e.g. accelerometers, touch screens) has resulted in the need to more tightly integrate analog devices with digital functionality to pre-process and communicate data. Most 8-bit devices do not offer the performance to sustain these tasks without significant increases in MHz and therefore power, and so embedded developers are required to look for alternative devices with more advanced processor technology. The 16-bit devices have previously been used to address energy efficiency concerns in microcontroller applications. However, the relative performance inefficiencies of 16-bit devices mean they will generally require a longer active duty cycle or higher clock frequency to accomplish the same task as a 32-bit device.

Ease of software development

Software development for ARM Cortex processor-based microcontrollers can be much easier than for 8-bit microcontroller products. Not only is the Cortex processor fully C programmable, it also comes with various enhanced debug features to help locating problems in software. There are also plenty of examples and tutorials on the internet, including many from ARM processor-based MCU vendor's websites, alongside any additional resources included in MCU development kits.

Cortex M3 Processor Simplified Block Diagram
Cortex M3 Processor Block Diagram. Ref

 Cortex M3 Core Peripherals

  • Nested Vectored Interrupt Controller
    The Nested Vectored Interrupt Controller (NVIC) is an embedded interrupt controller that supports low latency interrupt processing.
  • System control block
    The System control block (SCB) is the programmers model interface to the processor. It provides system implementation information and system control, including configuration, control, and reporting of system exceptions.
  • System timer
    The system timer, SysTick, is a 24-bit count-down timer. Use this as a Real Time Operating System (RTOS) tick timer or as a simple counter.
  • Memory protection unit
    The Memory protection unit (MPU) improves system reliability by defining the memory attributes for different memory regions. It provides up to eight different regions, and an optional predefined background region.

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