Page 43 - ARM Based Microcontroller Projects Using MBED

3.3 THE ARM PROCESSOR ARCHITECTURE 29
Cortex-R
Cortex-R series are real-time higher performance processors than the Cortex-M and some
members are designed to operate at high clock rates in excess of 1GHz. These processors are
commonlyusedinhard-diskcontrollers,networkdevices,automotiveapplications,andspecial-
izedinhigh-speedmicrocontrollerapplications.Cortex-R4andCortex-R5aretheearlymembers
andcanbeusedatclockspeedsofupto600MHz.Cortex-R7isanewermemberthatincorporates
11-stage pipeline for high performance and it can operate in excess of 1GHz. Although the Cor-
tex-R processors are high performance, their architecture is complex and these processors
consume high power, making them unsuitable for use in mobile battery powered devices.

Cortex-A
Cortex-A are the highest performance ARM processors designed for use with real-time op-
erating systems in mobile applications such as in mobile phones, tablets, GPS devices, games
consoles, and so on. These processors support advanced features for operating systems such as
Android, ioS, Linux, Windows, etc. In addition, advanced memory management is supported
with virtual memory. Early members of the family included processors such as Cortex-A5 to
Cortex-A17, based on the ARMv7-A architecture. Latest members of the family are the Cortex-
A50 and Cortex-A72 series designed for low-power and very high-performance mobile appli-
cations. These processors are built using the ARMv8-A architecture which offers 64-bit energy-
efficient operation with the capabilities of more than 4GB of physical memory.

3.3.3 Cortex-M Processor Comparison

A comparison of the various Cortex-M series processors is given in Table 3.1. As can be
seen from this table, Cortex-M0 and Cortex-M0+ are used at low speed and low power con-
sumption applications. Cortex-M1 is optimized for use in programmable gate array applica-
tions. Cortex-M3 and Cortex-M4 are medium-power processors used in microcontroller
applications with the Cortex-M4 supporting DSP and floating point arithmetic operations.
Cortex-M7 is a high-performance member of the family which is used in applications requir-
ing higher performance than the Cortex-M4.

TABLE 3.1 Cortex-M Processor Comparison
Processor Description
Cortex-M7 High-performance processor, used in applications where Cortex-M4 is not fast enough, supports
DSP and single and double precision arithmetic
Cortex-M4 Similar architecture as the Cortex-M3 but includes DSP and floating point arithmetic, used in
high-end microcontroller-type applications
Cortex-M3 Very popular, low power consumption, medium performance, debug features, used in
microcontroller-type applications
Cortex-M1 Designed mainly for programmable gate array applications
Cortex-M0+ Lower power consumption and higher performance than the Cortex-M0
Cortex-M0 Low power consumption, low to medium performance, smallest ARM processor