Microcontroller Vs Microprocessor for RTOS

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

Reply to
s_subbarayan
Loading thread data ...

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
 Click to see the full signature
Reply to
RusH

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).

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.

Hope springs eternal.

--
Tim Wescott
Wescott Design Services
 Click to see the full signature
Reply to
Tim Wescott

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 :-)
 Click to see the full signature
Reply to
42Bastian Schick

What is _your_ definition of a microcontroller ? Registersize ?

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

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

But it seems to.

--
42Bastian
Do not email to bastian42@yahoo.com, it's a spam-only account :-)
 Click to see the full signature
Reply to
42Bastian Schick

Or rather a bragging session ?

Reply to
Lanarcam

One Word "OVERHEAD"

Reply to
Neil Kurzman

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.

Reply to
gunda123

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.