The ARM (Advanced RISC Machines) architecture is a microprocessor architecture designed to produce light and energy-efficient processors based on the RISC (Reduced Instruction Set Computing) principle. ARM processors are typically used through cores designed and licensed globally by ARM Ltd. The architecture is equipped with technical features such as 32-bit and 64-bit addressing, Thumb-2 instruction set, advanced interrupt structures, Memory Protection Units (MPU), Digital Signal Processing (DSP) instructions, and Optional Floating Point Units (FPU).
Today's embedded systems require smaller, faster, and more energy-efficient hardware. Processor architectures that meet these requirements, from mobile devices to IoT (Internet of Things) sensors, medical devices to automotive, form the heart of system design. In this context, the ARM architecture is one of the cornerstones of modern embedded system design, standing out with its low power consumption, high processing efficiency, and modular structure. This structure makes ARM processors widely usable not only in microcontrollers but also in areas such as Mobile Devices, Portable Computers, Smart Home Systems, and Artificial Intelligence Applications.
History and Development Process
The origins of the ARM architecture date back to the Acorn RISC Machine design developed by Acorn Computers in the 1980s. This initial architecture set out with the goal of low transistor count and high efficiency, and the first processor prototype, ARM1, was produced in 1985. In the continuing process, ARM Ltd. was founded in 1990 through a partnership between Apple and VLSI Technology, and the architecture evolved and became widespread. While the ARM6 series, introduced in 1994, attracted attention with its mobile compatibility; the ARM7TDMI model gained great acceptance in the world of embedded systems, for example, it was used in Nokia phones. The Cortex series (M, A, R), introduced from 2004 onwards, segmented the architecture, offering optimized solutions for each application type. Over time, the ARM architecture transformed into an ecosystem that includes not only processors but also software development tools, security solutions, and artificial intelligence accelerators. With Apple's ARM-based M1 and M2 chips, this architecture has found its place not only in embedded systems but also in desktop and laptop computers.
Historical Development of ARM Architecture (Mehmet Alperen Bakıcı)
Technical Specifications of the Architecture
The ARM architecture is a RISC (Reduced Instruction Set Computing) architecture developed with the goal of high efficiency and low energy consumption. This approach ensures that the processor only supports basic commands, offering less transistor usage, lower power consumption, and simpler hardware design. However, what truly makes the ARM architecture powerful is the rich hardware and software capabilities built upon this simple foundation.
Thumb and Thumb-2 Instruction Sets
ARM processors support the classic 32-bit ARM instruction set as well as Thumb and the more advanced Thumb-2 instruction sets. Thumb-2 combines 16-bit and 32-bit instructions, reducing code density and enabling processing with less memory space without sacrificing performance. This structure creates a significant advantage, especially in embedded systems with limited Flash memory.
Pipeline Architecture
ARM cores operate with a multi-stage Pipeline structure. A typical Cortex-M core uses a 3 to 6-stage Pipeline, while in more advanced Cortex-A series, this number increases further. Thanks to this structure, while one instruction is being executed, the next instruction can be fetched, and another can be decoded. Thus, the processor achieves maximum processing capacity with every clock cycle.
NVIC - Nested Vectored Interrupt Controller
NVIC (Nested Vectored Interrupt Controller) is an integrated interrupt control unit found in ARM Cortex-M cores. With features such as software-controlled prioritization, priority-based masking, and nested interrupt handling, it provides high compatibility with real-time operating systems (RTOS). Thanks to NVIC, interrupt operations are managed extremely quickly and precisely.
MPU - Memory Protection Unit
MPU (Memory Protection Unit) allows the definition of access permissions for different memory regions. This feature is particularly used in applications critical for security and reliability. For example, a task can only access its own memory; access to other tasks' memory can be prevented. This increases software security at the processor level.
FPU - Floating Point Unit and DSP Support
Cores like Cortex-M4, M7, and M55 optionally include a single or double-precision floating point unit (FPU). This unit significantly increases performance by accelerating mathematical operations at the hardware level. Additionally, DSP (Digital Signal Processing) instructions included in these cores provide hardware acceleration for signal processing, filtering, FFT, and similar operations.
Low Power Consumption and Sleep Modes
The ARM architecture is one of the most successful solutions in the industry in terms of power efficiency. The cores minimize power consumption with different sleep modes such as Sleep, Deep Sleep, and Standby. Furthermore, thanks to the WIC (Wake-up Interrupt Controller), the processor wakes up only when needed. This structure is of critical importance, especially in battery-powered IoT (Internet of Things) devices.
ARM Core Families
The ARM architecture offers processor cores that differ according to the application type. These cores are basically divided into three main categories: Cortex-M, Cortex-A, and Cortex-R. Each family is optimized for different performance, power consumption, and system requirements.
Cortex-M Series: Optimization for Microcontrollers
Cortex-M cores are designed for embedded systems requiring low power consumption and hardware simplicity. They are widely used especially in RTOS (Real-Time Operating System) supported systems.
ARM Cortex-M Series Technical Specifications (Generated with Artificial Intelligence)
Cortex-A Series: Application Processors
The Cortex-A family is developed for operating system-supported and high processing power demanding applications. This series is found in Android phones, Raspberry Pi, and other Linux-based systems.
Technical Specifications and Typical Application Areas of ARM Cortex-A Series (Generated with Artificial Intelligence)
Cortex-R Series: Real-Time System Applications
The Cortex-R family is developed for real-time systems requiring high stability and low latency. Cores in this series offer high fault tolerance and deterministic behavior.
Technical Specifications and Usage Areas of ARM Cortex-R Series (Generated with Artificial Intelligence)
Application Areas of ARM Cortex Cores
The ARM architecture provides effective solutions for embedded systems in various sectors thanks to its customizable core design. ARM Cortex series are optimized for specific application types. This versatility allows for a wide range of uses, from microcontroller level to applications requiring high processing power.
The graph below represents the common application areas where different Cortex cores are used. The data provides an estimated distribution based on technical documentation, manufacturer datasheets, and sectoral analysis reports.
Estimated Distribution of ARM Cortex Cores by Usage Area Based on Technical Sources (Mehmet Alperen Bakıcı)
