Why ARM is Most Popular? ARM Architecture

Introduction of ARM:

ARM stands for Advanced RISC (reduced instruction set computer) machine.  ARM started life as part of Acorn makers of the BCC computer and now designs chips for Apple iPad. The first ARM was established at Cambridge University in 1978. The Acorn group computers have developed the first ARM commercial RISC processor in 1985. ARM was founded and very popular in 1990. The ARM using more than 98% of the mobile phones in 2007 and 10 billion processors are shipped in 2008. ARM is the latest technology which replaced by microcontrollers and microprocessors. Basically ARM is a 16 bit/ 32 bit Processors or Controllers. ARM is the heart of advanced digital products like mobile phones automotive systems digital cameras and home networking and wireless technologies.

General ARM Chip Diagram
General ARM Chip Diagram

Why ARM is most popular:

  • ARM is the most popular processor, particularly used in portable devices due to its low power consumption and reasonable performance.
  • ARM has got better performance when compared to other processors. The ARM processor is basically consisting of low power consumption and low cost. It is very easy to use ARM for quick and efficient application developments so that is the main reason why ARM is most popular.

Introduction to ARM Architecture Families:

ARM Architecture Families
ARM Architecture Families

Features of Different ARM Versions:

Version 1:

The ARM version one Architecture:

  • Software interrupts
  • 26-bit address bus
  • Data processing is slow
  • It supports byte, word, and multiword load operations

Version 2:

  • 26-Bit address bus
  • Automatic instructions for thread synchronization
  • Co-processor support

Version 3:

  • 32-Bit addressing
  • Multiple data support (like 32 bit=32*32=64).
  • Faster than ARM version1 and version2

Version 4:

  • 32-bit address space
  • Its support T variant:16 bit THUMB instruction set
  • It supports M variant: long multiply means give a 64-bit result

Version 5:

  • Improved ARM THUMB interworking
  • Its supports CCL instructions
  • It support E variant: Enhanced DSP Instruction set
  • It supports S variant:  Acceleration of Java byte code execution

Version 6:

  • Improved memory system
  • Its supports a single instruction multiple data

ARM Nomenclature:

There are different versions of ARM, like ARMTDMI, ARM10XE, the meaning of TDMI and XE is given below:

ARM {X}{Y}{Z}{T}{D}{M}{I}{E}{J}{F}{S}

  • X – Family
  • Y – Memory management
  • Z – Cache
  • T – THUMB 16-bit decoder
  • D – JTAG Debug
  • M – Fast multiplier
  • I – Embedded ICE macrocell
  • E – Enhanced Instruction
  • J – Jazelle (Java)
  • F – Vector floating-point unit
  • S – Synthesizable version

ARM Architecture:

ARM is a load-store reducing instruction set computer architecture; it means the core cannot directly operate with the memory. All data operations must be done by registers with the information which is located in the memory. Performing the operation of data and storing the value back to the memory.  ARM consist of 37 register sets, 31 are general-purpose registers and 6 are status registers. The ARM uses seven processing modes that are used to run the user task.

  • USER mode
  • FIQ mode
  • IRQ mode
  • SVC mode
  • UNDEFINED mode
  • ABORT mode
  • THUMB mode

The user mode is a normal mode; which has the least number of registers. It doesn’t have SPSR and limited access to the CPSR. The FIQ and IRQ are the two interrupt caused modes of the CPU. The FIQ is processing past interrupt and IRQ is slandered interrupt. The FIQ mode has an additional five banked registers to provide more flexibility and high performance when critical interrupts are handling. The Supervisor mode is the software interrupt mode of the processor to start-up or reset. The Undefined mode traps illegal instructions is executed. The ARM core consists 32-bit data bus and faster data flow. In THUMB mode the 32-bit of data divided into 16-bits and increases the processing speed.

Some of the registers are reserved in each mode for specific use by the core. The reserved registers are

  • SP (stack pointer).
  • LR (link register).
  • PC (program counter).
  • CPSR (current program status register).
  • SPSR (saved program status register).

The reserved registers are used for specific functions. The SPSR and CPSR contain the status control bits of specific properties. These properties are defining operating mode, ALU status flag, Interrupt enable or disable flags. The ARM core is operating in two states 32-bit state or THUMBS state.

ARM Mode Selection Registers

ARM Mode Selection Registers

ARM BASED Temperature Measurement:

Temperature is the most important parameter in industrial applications. Accuracy of measured and controlled is very essential. More industrials transformers are damaged by high voltage and overload and high temperature. Accuracy of temperature measured and controlled is highly demanding. This Project is designed to interface the temperature sensor to an ARM-based microcontroller.

Industrial Temperature Controller
Industrial Temperature Controller

Working Procedure:

The LPC2148 is a 16/32 bit ARM7 CPUThe temperature sensor LM35 is an analog sensor, connected to the LPC2148 microcontroller analog channel. The slandered temperature values are pre-programmed in the microcontroller. The graphical LCD is connected to the microcontroller output pins. The temperature sensor monitors the temperature every sec. When the temperature is increased due to overload then the sensor sends the analog signal to the microcontroller. The microcontroller gives the alerts through the buzzer and the LCD display. The LCD displays the temperature on the screen. This application is used in industries for safety purposes.

ARM7 Block Diagram and Features:

ARM7 Block Diagram
ARM7 Block Diagram

Features of ARM7:

  • The ARM7 is a 16/31 – Bit bus
  • The static Ram is 40 kb
  • On-chip flash programmable memory is 512kb
  • It is a high-speed controller 60 MHz operation
  • Two 10 bit ADC converters provide a total of 14 analog inputs
  • One 10- bit D/A converter
  • Two 32 bit timers/counters
  • 4- CCM (Capture Compare Modulation), 6-PWM, Watchdog timer
  • One RTC, 9 interrupts
  • One I2C protocol, SPI protocols, SSP protocol
  • Two UART serial communication protocols


  • Industrial control
  • Medical systems
  • Communication gateway
  • Embedded soft modem
  • General-purpose Applications
  • Access control
  • Point of scale

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