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SELECTION OF PROCESSOR 

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• Performance Consideration.

• Power consideration.

•

Peripheral set.• Operation Voltage.

• Specialied Processing !nits

SELECTION OF PROCESSOR 

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Performance Consideration

• First and Foremost consideration in selecting

the processor 

•

Performance speed depends on its architect"reand silicon design

• Presence of cache### red"ces data fetch timing

•

Pipelining s"perscalar architect"res and m"lticores ##### impro$es the performance .

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• E$ol"tion of fa%rication tech helped pac&ing

more transistor in same area there%' red"cing

the propagation dela'.

• Rather than stating the cloc& fre("enc' of the

 processor   which has limited significance to its

 processing power) than descri%ing then

capa%ilit' in a standard notation.

Performance Consideration

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Standard Notation

• *IPS# *illion Instr"ctions Per Second

• Core *ar& # %est wa' to compare the

 performance of $ario"s processor • S*I+# Single Instr"ction,*"ltiple +ata

• -aelle# -a$a cceleration

To impro$e m"ltimedia and -V*e/ec"tion speeds.

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Power consideration

• Increasing the logic densit' and cloc& speed has ad$erse impact on power

re("irement of the processor.

• higher cloc& implies faster charge and discharge c'cle leading to more

 power cons"mption.

• *ore logic leads to higher power densit' there %' ma&ing the heat

dissipation diffic"lt.

•

F"rther with more emphasis on greener technologies and man' s'stem

 %ecoming %atter' operated) it is important the design is for optimal power

"sage.

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Low Power cons"ming techni("es0

• Techni("es li&e fre("enc' scaling#red"cing the cloc& fre("enc' of the

 processor depending on the load .

• Voltage scaling#$ar'ing the $oltage %ased on load can help in achie$ing

low power "sage.

• F"rther as'mmetric m"ltiprocessors) "nder near ideal conditions) can

effecti$el' power off the more powerf"l core and load the less powerf"l

core for performing the tas&s.

• SoC  comes with ad$anced power gating techni("es  that can sh"tdown

cloc&s and power to "n"sed mod"les.

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Peripheral set0

• E$er' s'stem design needs) apart from the processor )man' other

 peripherals for inp"t and o"tp"t operation.

• Since in an em%edded s'stem) almost all the processors "sed are SoCs)it is

 %etter if the necessar' peripherals are a$aila%le in the chip itself .

• This offers $ario"s %enefits compared to peripherals in e/ternal IC1s s"ch

as optimal power architect"re) effecti$e data comm"nication "sing

+*)Lower 2o* ect.

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Operating Voltage

• Each and e$er' processor will ha$e its own ha$e its own operating $oltage

condition.

• The operating $oltage ma/im"m and minim"m ratings will %e pro$ided in

the respecti$e data sheet or "ser man"al.

• 3hile higher end processors t'picall' operating with 4 to 5 $oltages

incl"ding 6.7V for core,nalog"e domains )8.8V for IO lines) needs

specialied P*IC de$ices) it is deciding factor in low end micro#controllers %ased on the inp"t $oltage.

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Floating point co#processor

• RISC core s"pports primaril' integer onl' instr"ction set.

• 9ence presence of a FP Co#processor can %e $er' helpf"l in

application in$ol$ing comple/ mathematical operations

incl"ding m"ltimedia) image )codes) signal processing etc

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:raphic processing "nit;:P!<

• :P!;:raphic Processing !nit< also called as Vis"al processing "nit is

responsi%le for drawing images on the frame %"ffer memor' to %e displa'ed.

• Since h"man $is"al perception needed at#least 6= frames per second for a

smooth $iewing )drawing for 9+ displa's in$ol$es a lot of data %andwidth.

• lso with increasing graphic re("irements s"ch as te/t"res) lighting shaders

ect):P!1s ha$e %ecome a mandator' re("irements for mo%ile phones )gaming

consoles ect..

• Vario"s :P!1s li&e R*1s *LI)PowerV>)open:L ect are increasing

a$aila%le in higher end processors.

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Specialied Processing "nit

• part from the core ) presence of $ario"s co#processors and specialied

 processing "nits can help achie$ing necessar' processing performance.

• Co#processors e/ec"te the instr"ctions fetched %' the primar' processor

there%' red"cing the load on primar'.

• Some of the pop"lar co#processors incl"de.

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