What is ARM Cortex Microcontroller

ARM Cortex Microcontrollers are a series of low power, high performance 32-bit and 64-bit RISC core processors optimized for embedded systems. They are designed and licensed by ARM Holdings and manufactured by various semiconductor companies. The Cortex series offers a wide range of cores optimized for different applications, making them highly popular in embedded electronics.

Key Features of ARM Cortex Microcontrollers

Here are some of the key features that make ARM Cortex microcontrollers highly desirable for embedded systems:

• Power Efficient – ARM cores are designed to provide high performance at very low power, resulting in excellent energy efficiency. This allows longer battery life in portable devices.
• High Performance – Advanced RISC architecture and optimizations provide very high instructions per clock cycle, enabling complex tasks.
• Small Size – Efficient 16/32 bit Thumb instruction set results in very small die size, reducing costs.
• Real Time Performance – Low interrupt latency and fast context switching provides real time responsiveness.
• Scalable – The Cortex family scales from the tiny Cortex-M0 for simple tasks to Cortex-A series for complex applications.
• Customizable – Companies can license, customize and incorporate ARM cores into their own ASIC and SoC designs.
• Software Support – Support for operating systems like Linux, Android, Windows IoT, etc. Large open source software support.
• Development Ecosystem – Availability of wide range of development tools and debuggers from ARM and partners.

ARM Cortex Processor Families

ARM offers a wide range of processor cores optimized for different applications. The major families are:

Cortex-M Series

The Cortex-M series targets embedded and IoT applications with its small size, low power, real-time capabilities, and integration of memory and peripherals on-chip. Key members include:

• Cortex-M0/M0+ – For basic and cost sensitive applications like home appliances, toys etc.
• Cortex-M3 – Mid range 32-bit performance for industrial, automotive applications.
• Cortex-M4 – Digital Signal Controllers with DSP extensions and Floating Point Unit.
• Cortex-M7 – Highest performance M-series core with superscalar architecture.
• Cortex-M23/M33 – Adds security extensions for trusted execution environments.

Cortex-R Series

The Cortex-R series focuses on reliability and functional safety for mission critical applications like automotive, industrial control and medical devices. Key members are:

• Cortex-R4 and Cortex-R5 – For reliable real time embedded applications requiring safety certification.
• Cortex-R7 and Cortex-R8 – High performance real-time safe cores with lock-step capability.

Cortex-A Series

The Cortex-A series provides high performance computing required for application processors in devices like smartphones, tablets, smart TVs, AR/VR headsets and single board computers. Key members include:

• Cortex-A5 and Cortex-A7 – Power efficient 32-bit multicore application processor cores.
• Cortex-A53 and Cortex-A55 – Ultra efficient 64-bit multicore cores for mainstream mobile devices.
• Cortex-A72 and Cortex-A76 – High performance 64-bit multicore cores.
• Cortex-A77 – Latest high-end core with machine learning optimizations.

Microcontroller vs Microprocessor

ARM Cortex series has cores targeted for both Microcontrollers and Microprocessors. What are the key differences?

Microcontrollers

• System on Chip with integrated CPU, memory, peripherals.
• Optimized for embedded control applications.
• Real time behavior, low latency interrupts.
• Low power consumption for battery powered devices.
• Examples: Cortex-M0, M3, M4 etc.

Microprocessors

• Standalone general purpose CPU requiring external chips.
• Optimized for high performance computing.
• Used in PCs, Servers, Smartphones etc.
• High power consumption.
• Examples: Cortex-A Series chips.

Development Tools and Software

ARM offers a robust ecosystem of development tools and software support:

• IDEs – GCC, Keil MDK, IAR Embedded Workbench, ARM DS-5
• Debuggers – JTAG debuggers like Segger J-Link, ST-Link
• OS Support – FreeRTOS, ARM Mbed OS, Linux, Windows IoT etc.
• Modeling – Cycle accurate models for early software development.
• IP Cores – ARM offers various peripheral and interface IP cores.

ARM has a large global ecosystem of partners providing development boards, tools and software solutions.

Licensing and Manufacturing

ARM Holdings licenses its processor IP cores to many semiconductor companies instead of manufacturing the chips themselves. Companies like STMicroelectronics, NXP, Qualcomm, Samsung, Apple etc take ARM’s IP cores and integrate them into their own System on Chip designs which are then fabbed at foundries.

This fabless licensing model allows ARM architecture to be supported by a wide range of chip vendors at various price points. Original chip design companies can achieve differentiation while keeping their R&D focused on actual chip design rather than microarchitecture design.

Applications of ARM Microcontrollers

Given their power efficiency, performance and flexibility, ARM cores find use in nearly all embedded electronic applications:

• Consumer Electronics – Smartphones, tablets, smartwatches, digital cameras etc.
• Industrial Automation – Motor controls, industrial PLCs, SCADA systems.
• Medical Devices – Diagnostics equipment, imaging systems, smart wearables.
• Automotive – Engine control units, infotainment systems, self driving systems.
• IoT Devices – Smart home, wearables, sensors, edge nodes.

ARM’s large library of microcontroller, graphics, interface and security cores allows system on chip integration for specific applications.

Comparison with other Architectures

Let’s compare ARM with some other popular embedded microcontroller architectures:

ARM Cortex M4

• 32 bit RISC architecture
• High performance, low power
• Memory protection unit
• DSP extensions
• Wide software and tools support

AVR

• 8 bit Harvard architecture
• Very low cost
• Low power
• Small code size
• Open source friendly

PIC

• 16/32 bit modified Harvard
• Medium performance
• Very low cost
• Limited software support

ARM Cortex M cores provide significantly better performance while maintaining low cost and power consumption. The availability of a large variety of cores for different applications has made ARM the architecture of choice for embedded electronics.

Conclusion

ARM Cortex series microcontrollers provide an ideal combination of performance, power efficiency, customizability and software support for the full range of embedded electronics applications. Their RISC architecture, ultra low power designs and a robust development ecosystem has made ARM the most popular 32-bit architecture in the embedded space today.