Microcontroller Vs Microprocessor for RTOS
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Microcontroller Vs Microprocessor for RTOS

 
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Guest
Posted: Mon Jan 31, 2005 7:56 am    Post subject: Microcontroller Vs Microprocessor for RTOS Reply with quote
Dear all,
I am just curious to know why almost all commercial popular RTOS like
RTLINUX,Vxworks work mainly on Micro processor instead of
Microcontrollers?
AFAIK,I have seen Vxworks work on Boards like Intel x86,powerpc,ARM and
all mentioned processor boards instead of real microcontrollers like
8051,68HC series from motorola and so.
Why do RTOS prefer microprocessors as compared to microcontrollers?

Though I know few RTOS like RTX-51 which runs exclusively only on 8051
microcontrollers,still such things are not so common in embedded world.

I would like to hear some real facts behind this decision instead of
starting a religious war of using microcontrollers or microprocessors
with RTOS...

Regards,
s.subbarayan
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RusH
Guest
Posted: Mon Jan 31, 2005 7:56 am    Post subject: Re: Microcontroller Vs Microprocessor for RTOS Reply with quote
s_subbarayan@rediffmail.com wrote :

Quote:
Dear all,
I am just curious to know why almost all commercial popular RTOS
like RTLINUX,Vxworks work mainly on Micro processor instead of
Microcontrollers?
AFAIK,I have seen Vxworks work on Boards like Intel
x86,powerpc,ARM and all mentioned processor boards instead of real
microcontrollers like 8051,68HC series from motorola and so.
Why do RTOS prefer microprocessors as compared to
microcontrollers?

are you a sales person ? a manager (brr) ?
those are basics - you DONT NEED an OS on something with 128 bytes of
ram, you need every byte of resources. RTOS is a luxury


Pozdrawiam.
--
RusH //
http://randki.o2.pl/profil.php?id_r=352019
Like ninjas, true hackers are shrouded in secrecy and mystery.
You may never know -- UNTIL IT'S TOO LATE.
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42Bastian Schick
Guest
Posted: Mon Jan 31, 2005 7:56 am    Post subject: Re: Microcontroller Vs Microprocessor for RTOS Reply with quote
Quote:
AFAIK,I have seen Vxworks work on Boards like Intel x86,powerpc,ARM and
all mentioned processor boards instead of real microcontrollers like
8051,68HC series from motorola and so.

What is _your_ definition of a microcontroller ? Registersize ?

Mine is: A microntroller is a cpu + periperals on the same chip.

Quote:
Though I know few RTOS like RTX-51 which runs exclusively only on 8051
microcontrollers,still such things are not so common in embedded world.

Ouch, do you want to start another RTOS or not thread :-))

Quote:
I would like to hear some real facts behind this decision instead of
starting a religious war of using microcontrollers or microprocessors
with RTOS...

But it seems to.
--
42Bastian
Do not email to bastian42@yahoo.com, it's a spam-only account :-)
Use <same-name>@monlynx.de instead !
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42Bastian Schick
Guest
Posted: Mon Jan 31, 2005 7:56 am    Post subject: Re: Microcontroller Vs Microprocessor for RTOS Reply with quote
On 30 Jan 2005 21:36:22 -0800, s_subbarayan@rediffmail.com wrote:

Quote:
Dear all,
I am just curious to know why almost all commercial popular RTOS like
RTLINUX,Vxworks work mainly on Micro processor instead of
Microcontrollers?

I don't think they make such difference. Some companies even differ
between microcontroller, embedded microprocessor and microprocessor.

For an (RT)OS it is only interressting to know which architecture the
CPU has, is it 8,16,32 or more bits, does it have an MMU or FPU etc.

Esp. for VxWorks I know that it runs also on ARM base microcontrollers
(taking the definition, that a microcontroller is an CPU + peripherals
on the same chip).

--
42Bastian
Do not email to bastian42@yahoo.com, it's a spam-only account :-)
Use <same-name>@monlynx.de instead !
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Tim Wescott
Guest
Posted: Mon Jan 31, 2005 7:56 am    Post subject: Re: Microcontroller Vs Microprocessor for RTOS Reply with quote
s_subbarayan@rediffmail.com wrote:
Quote:
Dear all,
I am just curious to know why almost all commercial popular RTOS like
RTLINUX,Vxworks work mainly on Micro processor instead of
Microcontrollers?

You mean "heavily advertised". Those two, in particular, are huge. The
last time I checked VxWorks wasn't even available for anything less than
a 32-bit processor. There are smaller micro kernels out there made for
8- and 16-bit processors (MicroC/OS is notable).

Quote:
AFAIK,I have seen Vxworks work on Boards like Intel x86,powerpc,ARM and
all mentioned processor boards instead of real microcontrollers like
8051,68HC series from motorola and so.
Why do RTOS prefer microprocessors as compared to microcontrollers?

Because the RTOS takes chip resources to run, and microprocessors

generally have more resources to spend. Most significantly when you do
a task swap you need to save the task's stack frame so you need storage
for as many stack frames as you have separate tasks. This can suck up
very large amounts of memory very quickly.

Also, the benefits of an RTOS diminish as the application gets small,
and microcontrollers are more likely to have small applications. For a
small enough application you'll spend more time dinking with the RTOS to
get it up and running than you'll save by having it there.

Quote:
Though I know few RTOS like RTX-51 which runs exclusively only on 8051
microcontrollers,still such things are not so common in embedded world.

I would like to hear some real facts behind this decision instead of
starting a religious war of using microcontrollers or microprocessors
with RTOS...

Hope springs eternal.
Quote:

Regards,
s.subbarayan



--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
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Lanarcam
Guest
Posted: Mon Jan 31, 2005 1:13 pm    Post subject: Re: Microcontroller Vs Microprocessor for RTOS Reply with quote
Quote:
I would like to hear some real facts behind this decision i­nstead
of starting a religious war of using microcontrollers or
micro­processors with RTOS...
But it seems to.

Or rather a bragging session ?
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Charles Krug
Guest
Posted: Mon Jan 31, 2005 7:17 pm    Post subject: Re: Microcontroller Vs Microprocessor for RTOS Reply with quote
On Mon, 31 Jan 2005 07:51:24 GMT, 42Bastian Schick <bastian42@yahoo.com> wrote:
Quote:
On 30 Jan 2005 21:36:22 -0800, s_subbarayan@rediffmail.com wrote:

Dear all,
I am just curious to know why almost all commercial popular RTOS like
RTLINUX,Vxworks work mainly on Micro processor instead of
Microcontrollers?

I don't think they make such difference. Some companies even differ
between microcontroller, embedded microprocessor and microprocessor.

For an (RT)OS it is only interressting to know which architecture the
CPU has, is it 8,16,32 or more bits, does it have an MMU or FPU etc.

Esp. for VxWorks I know that it runs also on ARM base microcontrollers
(taking the definition, that a microcontroller is an CPU + peripherals
on the same chip).


Well, if one looks at the cross-post list, one might suspect that the OP
is trolling by posting things in terms designed to incite to groups
likely to have differing opinions, but I digress.

I remember when my computer was a Z80.

Now a Z80 is sold as a microcontroller.

Just a data point.
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Juhan Leemet
Guest
Posted: Tue Feb 01, 2005 7:14 am    Post subject: Re: Microcontroller Vs Microprocessor for RTOS Reply with quote
On Mon, 31 Jan 2005 14:17:55 +0000, Charles Krug wrote:
Quote:
On Mon, 31 Jan 2005 07:51:24 GMT, 42Bastian Schick <bastian42@yahoo.com> wrote:
On 30 Jan 2005 21:36:22 -0800, s_subbarayan@rediffmail.com wrote:

Dear all,
I am just curious to know why almost all commercial popular RTOS like
RTLINUX,Vxworks work mainly on Micro processor instead of
Microcontrollers?

I don't think they make such difference. Some companies even differ
between microcontroller, embedded microprocessor and microprocessor.

For an (RT)OS it is only interressting to know which architecture the
CPU has, is it 8,16,32 or more bits, does it have an MMU or FPU etc.

Esp. for VxWorks I know that it runs also on ARM base microcontrollers
(taking the definition, that a microcontroller is an CPU + peripherals
on the same chip).


Well, if one looks at the cross-post list, one might suspect that the OP
is trolling by posting things in terms designed to incite to groups
likely to have differing opinions, but I digress.

I remember when my computer was a Z80.

Now a Z80 is sold as a microcontroller.

Just a data point.

I also remember having my own first computer: Z80 running CP/M. I used it
to hack some industrial and laboratory control stuff. That ran under a
home-brew foreground/background kinda scheme, sort of like RT-11, etc.

I remember trying to write some mini-O/S for the Z80 and being frustrated
by its lack of base+index instruction addressing, so you really could not
have any relocatable code. MP/M used a horrible hack for its relocatable
code modules: it compiled them 2x, with a 0100h offset, and saved the code
as absolute code with a bitmap identifying the relocatable addresses. Then
you needed a special loader program to use that bitmap to translate
the absolute addresses. Yuck! ISTR the Z80 was also rather weak at
stack+offset operations, so handling stack frames was awkward. It had
strong index+offset support with a couple of special purpose index
registers, to make block operations fly, but more or less on a stand-alone
basis. Two register sets supported a foreground/background scheme well,
using interrupts to trigger context change. However, I came to the
conclusion that the Z80 (inheriting its faults from the 8080?) was really
not suitable for writing a general purpose (or even R/T?) O/S. It could
run a fixed set of code that was fixed in memory (e.g. ROM) quite well,
and we used it for many control applications: industrial, laboratory,
communications, etc. I thought the (later) 6809 had a much better CPU
architecture for general purpose O/S applications.

I guess what I'm saying is that numbers of bits, FPU, MMU are not
sufficient to characterize suitability of a CPU. You also have to look at
the instruction set, and addressing modes, etc.

Of course, you could always write an emulator... but then a Turing machine
could also execute an emulator... why bother? Pick a good CPU.

In general tho, I agree that a microcontroller = CPU + peripherals (and
memory?). So the Z8 and 8051 are microcontrollers. Dunno if there is any
RTOS available for them? I would expect that to be rather painful.

Nowadays, the M683xx are pretty impressive beasties? Buddies of mine have
worked with them. I get the impression they are quite good CPUs and also
have a bunch of peripherals bundled with them. They could be interesting.

--
Juhan Leemet
Logicognosis, Inc.
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Neil Kurzman
Guest
Posted: Tue Feb 01, 2005 7:57 am    Post subject: Re: Microcontroller Vs Microprocessor for RTOS Reply with quote
s_subbarayan@rediffmail.com wrote:

Quote:
Dear all,
I am just curious to know why almost all commercial popular RTOS like
RTLINUX,Vxworks work mainly on Micro processor instead of
Microcontrollers?
AFAIK,I have seen Vxworks work on Boards like Intel x86,powerpc,ARM and
all mentioned processor boards instead of real microcontrollers like
8051,68HC series from motorola and so.
Why do RTOS prefer microprocessors as compared to microcontrollers?

Though I know few RTOS like RTX-51 which runs exclusively only on 8051
microcontrollers,still such things are not so common in embedded world.

I would like to hear some real facts behind this decision instead of
starting a religious war of using microcontrollers or microprocessors
with RTOS...

Regards,
s.subbarayan

One Word "OVERHEAD"
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Guest
Posted: Thu Feb 03, 2005 8:03 pm    Post subject: Re: Microcontroller Vs Microprocessor for RTOS Reply with quote
Dear Subbu,

I think it may be this way if you are going for a specific applications
then the need for a specific controller comes into picture and then
they go for microcontrollers,

Usually an OS will be very generic and they operate on a generic
devices with so that the user will have a more flexibility for there
application but if you go for a microcontroller the devices on chip and
the controller will be very specific and the same code which is written
on the controller will have less portable options ,but if you consider
a pentium family for an example,if you have device driver for one
device on P3 the same code can be run on the P4 also.

Please let me know if i am wrong .
Thanks and Regard
Prashanth B.S.
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