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BOFH is offline BOFH
2008-04-02 , 15:33
Posts: 333 | Thanked: 32 times | Joined on Jul 2007
#1

I work on embedded systems, generally specialty networking gear like switches, routers, and security products. We use a commodity processor to handle administration tasks like web-based management, a command line interface, SNMP, etc. This processor runs an actual OS, which up to about six years ago would have been a commercial realtime package like vxWorks or QNX. In the last few years everything I've worked on has used Linux.

One question which comes up with reasonable frequency is why do embedded systems generally use RISC CPUs like PowerPC, MIPS, and ARM? Usually the question is phrased the other way around, "Why don't you just use x86?" To be clear: the processors used in the embedded systems I'm talking about are not the ultra-cheap 4, 8 or 16 bit CPUs you might think of when someone says "embedded". They are 32 or 64 bit CPUs, with memory protection and other features common to desktop CPUs. Asking why we're not using x86 is a legitimate question.

I'll cover four areas which push embedded systems towards non-x86 CPUs.

* Volume Discounts
* System on Chip (SoC)
* Production lifetime
* Power and heat
http://codingrelic.geekhold.com/2008...rocessors.html
 
TA-t3 is offline TA-t3
2008-04-03 , 19:05
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#2
This following part was a bit interesting:
For example in 2007 Gartner estimates that 264 million PCs were sold, nearly all of which contain an x86 processor. In the same year almost 3 billion ARM processors were sold.
I guess a huge amounts of ARM processors go into mobile phones, but I'm still surprised at the 3 billion CPUs.. in one year. There must be a lot more embedded applications out there than I imagined.
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tso is offline tso
2008-04-03 , 19:10
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#3
i think just about anything that has a kind of firmware have a arm based cpu in it...

not just phones, but maybe also things like dvd players and recorders, set top boxes of all kinds, home networking gear maybe?
 
fanoush is offline fanoush
2008-04-03 , 21:03
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#4
well as for numbers sold more important could be ordinary stuff like fridges, washing machines, microwave ovens, TVs, cameras, basically anything in your home with few buttons. also hardware for PC like network cards, bluetooth stuff (even bluetooth and wlan chips inside our tablets has one inside) or even hard drives and memory cards can have some sort of arm core inside. Simple arm7tdmi costs almost nothing today, see also ARM architecture. Of course there are other embedded cpus too which are even cheaper and simpler and are widely used too (like PIC or AVR) but ARM is more universal as it scales well from really simple stuff to more complex one.
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Last edited by fanoush; 2008-04-03 at 21:08.
 
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Benson is offline Benson
2008-04-03 , 21:13
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#5
Originally Posted by tso View Post
i think just about anything that has a kind of firmware have a arm based cpu in it...

not just phones, but maybe also things like dvd players and recorders, set top boxes of all kinds, home networking gear maybe?
Everything with firmware has a CPU or (maybe) MCU; not all of them are ARMs. But ARMs are quite popular in the segments you mentioned. All HP calculators (the real ones, not kiddie calculators) since 2002 are ARM based, though. And many phones have more than one, doing different things. (Nintendo DS has two dissimilar ARMs, doesn't it?)
 
nhanquy is offline nhanquy
2008-04-03 , 22:12
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#6
One big problem with the x86 is that it uses the little endian scheme instead of the big endian.
 
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GeneralAntilles is offline GeneralAntilles
2008-04-03 , 22:18
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#7
Originally Posted by nhanquy View Post
One big problem with the x86 is that it uses the little endian scheme instead of the big endian.
So do the tablets. (armel, ARM Endian Little, clever isn't it? )
 
TA-t3 is offline TA-t3
2008-04-04 , 11:12
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#8
ARM can be used in both little endian as well as big endian mode if I'm not mistaken. So can MIPS (which is actually used a lot in networking gear, as it turns out). That little endian mode is used on the N800 can sometimes be useful for us x86 PC owners, at least in principle - some data files can be used transparently on both, and there are less problems with porting some little-endian-only applications.
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Last edited by TA-t3; 2008-04-04 at 11:14.
 
fms is offline fms
2008-04-04 , 11:32
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#9
Originally Posted by nhanquy View Post
One big problem with the x86 is that it uses the little endian scheme instead of the big endian.
It is not a valid argument against using x86. There is absolutely no reason why an embedded system would use big-endian rather than little-endian mode. For example, most ARM-based systems use little-endian mode nowadays. SPARC (LEON) and 680x0 (Freescale) use big-endian mode.
 
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