IEEE Electrification Magazine - December 2017 - 50

The Cortex-A family is a suitable microprocessor architecture option for the CCPS digital core. ARM Cortex-A is
capable of undertaking complex computing tasks and
supporting multiple software applications. These processors provide the highest performance at low power, and
they have MMU support. They are used in a range of applications such as smartphones, digital televisions, mobile
computing platforms, IoT devices, networking, server solutions, and more. A comparison of different Cortex-A products for the two latest versions, ARMv7-A and ARMv8-A,
are presented in Table 1. The architectures are divided into
three types in terms of performance and efficiency. Efficiency is the output-to-input power ratio, and the fundamental difference between high-efficiency and
high-performance processors depends on the power budget at which the performance is optimized. In other
words, there is usually a tradeoff between performance
and efficiency. The high-performance architectures offer
the fastest operations with compromised efficiency, and
they are suitable for applications requiring a quick
response while efficiency is not of concern. The ultrahighefficiency cores have the most optimum proficiency,
while their performance is lower than that of the highperformance cores. The high-efficiency cores are between
the high-performance and ultrahigh-efficiency cores,
offering a balance of performance and efficiency for

TABLE 1. ARM Cortex-A products.
Feature

ARMv7-A

ARMv8-A

High performance

Cortex-A15
Cortex-A17

Cortex-A57
Cortex-A72

High efficiency

Cortex-A8
Cortex-A9

Cortex-A53

Ultrahigh efficiency

Cortex-A5
Cortex-A7

Cortex-A32
CortexA35

Source: ARM Holdings, www.arm.com.

various applications. ARMv8-A architecture processors,
like the Cortex-A72, Cortex-A57, Cortex-A53, and CortexA35 processors, have 64-b computing capability but also
support 32-b applications. High-performance cores in the
ARMv8-A category, such as the Cortex-A72 and CortexA57, can be paired with high-efficiency cores in the same
category, such as Cortex-A53 and Cortex-A35, with the
high-performance core delivering peak execution for
intensive tasks while background processing is performed
by the high-efficiency core. This combination, referred to
as big.LITTLE, results in improved overall system energy
efficiency and performance. The big.LITTLE architecture
can also be applied to ARMv7-A processors.
ARMv8-A and Cortex-A17 from the ARMv7-A family
were released after 2014. In the aerospace industry, a
major aspect of choosing a component is technology readiness, i.e., the maturity of the concept and hardware. In
addition, for the CCPS application, a balance of performance, efficiency, and cost is required. Therefore, architectures like the Cortex-A5, -A7, -A8, and -A9 are considered
acceptable for the CCPS digital core. Table 2 presents
a comparative analysis between the different processor architectures.
Cortex-A5, -A7, and -A8 have the same clock speed of
1 GHz, while Cortex-A9 has 2 GHz. However, when comparing microprocessors, the number of operations that the
processor can do in each clock cycle is an important
parameter. One such method of benchmarking processors
that is representative of system (integer) programming is
Dhrystone. Dhrystone benchmarking usually gives the
metric as either Dhrystone million instructions per second (DMIPS) or Dhrystone million instructions per second
per megahertz (DMIPS/MHz). As seen in Table 2, Cortex-A9
has a 2.5 DMIPS/MHz ratio, the highest among the selected architectures. However, compared to Cortex-A9, the
Cortex-A7 is 80% more power-efficient. If two Cortex-A7
processors are used in a multicore operation, they will
exhibit higher performance than a single-core Cortex-A9
as well as better power efficiency, but they will incur a
higher cost. The Cortex-A7 and -A9 are the most popular

TABLE 2. A comparison of ARM Cortex-A processors.
Features

Cortex-A5

Cortex-A7

Cortex-A8

Cortex-A9

Release date

December 2009

October 2011

July 2006

March 2008

Typical clock speed (GHz)

~1

~1

~1

~2

Cores

1-4

1-4

1

1-4

Dhrystone (DMIPS/MHz)

1.6

1.9

2

2.5

L1 instruction cache size (KB)

4-64

8-64

16-32

16-64

L1 data cache size (KB)

4-64

8-64

16-32

16-64

L2 cache (KB)

-

0-1,024

0-10,000

-

Source: ARM Holdings, www.arm.com.

50

I E E E E l e c t r i f i c ati o n M a gaz ine / DECEMBER 2017


http://www.arm.com http://www.arm.com

Table of Contents for the Digital Edition of IEEE Electrification Magazine - December 2017

IEEE Electrification Magazine - December 2017 - Cover1
IEEE Electrification Magazine - December 2017 - Cover2
IEEE Electrification Magazine - December 2017 - 1
IEEE Electrification Magazine - December 2017 - 2
IEEE Electrification Magazine - December 2017 - 3
IEEE Electrification Magazine - December 2017 - 4
IEEE Electrification Magazine - December 2017 - 5
IEEE Electrification Magazine - December 2017 - 6
IEEE Electrification Magazine - December 2017 - 7
IEEE Electrification Magazine - December 2017 - 8
IEEE Electrification Magazine - December 2017 - 9
IEEE Electrification Magazine - December 2017 - 10
IEEE Electrification Magazine - December 2017 - 11
IEEE Electrification Magazine - December 2017 - 12
IEEE Electrification Magazine - December 2017 - 13
IEEE Electrification Magazine - December 2017 - 14
IEEE Electrification Magazine - December 2017 - 15
IEEE Electrification Magazine - December 2017 - 16
IEEE Electrification Magazine - December 2017 - 17
IEEE Electrification Magazine - December 2017 - 18
IEEE Electrification Magazine - December 2017 - 19
IEEE Electrification Magazine - December 2017 - 20
IEEE Electrification Magazine - December 2017 - 21
IEEE Electrification Magazine - December 2017 - 22
IEEE Electrification Magazine - December 2017 - 23
IEEE Electrification Magazine - December 2017 - 24
IEEE Electrification Magazine - December 2017 - 25
IEEE Electrification Magazine - December 2017 - 26
IEEE Electrification Magazine - December 2017 - 27
IEEE Electrification Magazine - December 2017 - 28
IEEE Electrification Magazine - December 2017 - 29
IEEE Electrification Magazine - December 2017 - 30
IEEE Electrification Magazine - December 2017 - 31
IEEE Electrification Magazine - December 2017 - 32
IEEE Electrification Magazine - December 2017 - 33
IEEE Electrification Magazine - December 2017 - 34
IEEE Electrification Magazine - December 2017 - 35
IEEE Electrification Magazine - December 2017 - 36
IEEE Electrification Magazine - December 2017 - 37
IEEE Electrification Magazine - December 2017 - 38
IEEE Electrification Magazine - December 2017 - 39
IEEE Electrification Magazine - December 2017 - 40
IEEE Electrification Magazine - December 2017 - 41
IEEE Electrification Magazine - December 2017 - 42
IEEE Electrification Magazine - December 2017 - 43
IEEE Electrification Magazine - December 2017 - 44
IEEE Electrification Magazine - December 2017 - 45
IEEE Electrification Magazine - December 2017 - 46
IEEE Electrification Magazine - December 2017 - 47
IEEE Electrification Magazine - December 2017 - 48
IEEE Electrification Magazine - December 2017 - 49
IEEE Electrification Magazine - December 2017 - 50
IEEE Electrification Magazine - December 2017 - 51
IEEE Electrification Magazine - December 2017 - 52
IEEE Electrification Magazine - December 2017 - 53
IEEE Electrification Magazine - December 2017 - 54
IEEE Electrification Magazine - December 2017 - 55
IEEE Electrification Magazine - December 2017 - 56
IEEE Electrification Magazine - December 2017 - 57
IEEE Electrification Magazine - December 2017 - 58
IEEE Electrification Magazine - December 2017 - 59
IEEE Electrification Magazine - December 2017 - 60
IEEE Electrification Magazine - December 2017 - 61
IEEE Electrification Magazine - December 2017 - 62
IEEE Electrification Magazine - December 2017 - 63
IEEE Electrification Magazine - December 2017 - 64
IEEE Electrification Magazine - December 2017 - 65
IEEE Electrification Magazine - December 2017 - 66
IEEE Electrification Magazine - December 2017 - 67
IEEE Electrification Magazine - December 2017 - 68
IEEE Electrification Magazine - December 2017 - 69
IEEE Electrification Magazine - December 2017 - 70
IEEE Electrification Magazine - December 2017 - 71
IEEE Electrification Magazine - December 2017 - 72
IEEE Electrification Magazine - December 2017 - 73
IEEE Electrification Magazine - December 2017 - 74
IEEE Electrification Magazine - December 2017 - 75
IEEE Electrification Magazine - December 2017 - 76
IEEE Electrification Magazine - December 2017 - 77
IEEE Electrification Magazine - December 2017 - 78
IEEE Electrification Magazine - December 2017 - 79
IEEE Electrification Magazine - December 2017 - 80
IEEE Electrification Magazine - December 2017 - 81
IEEE Electrification Magazine - December 2017 - 82
IEEE Electrification Magazine - December 2017 - 83
IEEE Electrification Magazine - December 2017 - 84
IEEE Electrification Magazine - December 2017 - 85
IEEE Electrification Magazine - December 2017 - 86
IEEE Electrification Magazine - December 2017 - 87
IEEE Electrification Magazine - December 2017 - 88
IEEE Electrification Magazine - December 2017 - 89
IEEE Electrification Magazine - December 2017 - 90
IEEE Electrification Magazine - December 2017 - 91
IEEE Electrification Magazine - December 2017 - 92
IEEE Electrification Magazine - December 2017 - 93
IEEE Electrification Magazine - December 2017 - 94
IEEE Electrification Magazine - December 2017 - 95
IEEE Electrification Magazine - December 2017 - 96
IEEE Electrification Magazine - December 2017 - 97
IEEE Electrification Magazine - December 2017 - 98
IEEE Electrification Magazine - December 2017 - 99
IEEE Electrification Magazine - December 2017 - 100
IEEE Electrification Magazine - December 2017 - Cover3
IEEE Electrification Magazine - December 2017 - Cover4
http://www.nxtbook.com/nxtbooks/pes/electrification_december2019
http://www.nxtbook.com/nxtbooks/pes/electrification_september2019
http://www.nxtbook.com/nxtbooks/pes/electrification_june2019
http://www.nxtbook.com/nxtbooks/pes/electrification_march2019
http://www.nxtbook.com/nxtbooks/pes/electrification_december2018
http://www.nxtbook.com/nxtbooks/pes/electrification_september2018
http://www.nxtbook.com/nxtbooks/pes/electrification_june2018
http://www.nxtbook.com/nxtbooks/pes/electrification_december2017
http://www.nxtbook.com/nxtbooks/pes/electrification_september2017
http://www.nxtbook.com/nxtbooks/pes/electrification_march2018
http://www.nxtbook.com/nxtbooks/pes/electrification_june2017
http://www.nxtbook.com/nxtbooks/pes/electrification_march2017
http://www.nxtbook.com/nxtbooks/pes/electrification_june2016
http://www.nxtbook.com/nxtbooks/pes/electrification_december2016
http://www.nxtbook.com/nxtbooks/pes/electrification_september2016
http://www.nxtbook.com/nxtbooks/pes/electrification_december2015
http://www.nxtbook.com/nxtbooks/pes/electrification_march2016
http://www.nxtbook.com/nxtbooks/pes/electrification_march2015
http://www.nxtbook.com/nxtbooks/pes/electrification_june2015
http://www.nxtbook.com/nxtbooks/pes/electrification_september2015
http://www.nxtbook.com/nxtbooks/pes/electrification_march2014
http://www.nxtbook.com/nxtbooks/pes/electrification_june2014
http://www.nxtbook.com/nxtbooks/pes/electrification_september2014
http://www.nxtbook.com/nxtbooks/pes/electrification_december2014
http://www.nxtbook.com/nxtbooks/pes/electrification_december2013
http://www.nxtbook.com/nxtbooks/pes/electrification_september2013
http://www.nxtbookMEDIA.com