What is the sense of a RTOS on a single-chip microcontroller?

Hello,

I do not have a idea, where a RTOS on a singlechip microcontroller is
good for. I know, that it is good for making two (or more) processes
parallel but cannot imagine, how this works. O.K, a simple example to
make it clear. There is microcontroller and two processes shall run on
it. The first one ANDs two intput-pins and gives the result to an
output-pin. The second one ORs two other inputs and gives the result
to another output-pin. If I want to make this processes parallel I
write both commands into one program and they will run "parallel".
What would be the way, the RTOS would make this two processes
"parallel"?

Consider my furnace project.  Each MCU is constantly running a 1wire
search to check for buttons, scanning a 1wire temperature and humidity
module, talking to the gumstix via i2c, queuing up serial data for the
LCD, keeping track of the time, and keeping some LEDs updated.

Or look at something like eCos, which includes interrupt-driven device
drivers for serial, USB, ethernet, etc, and includes a full TCP/IP
stack and file system drivers for everything from flash to hard
drives.

The two "processes" don't have to both be applications.  You can have
one application (the "main" thread) and lots of threads taking care of
your devices.

And RTOS also provides a number of standard services, like networking,
serial channels (rs232, usb, SPI), file systems, etc.

"Paul Rosen" <proxx@lycos.de> wrote in message 
news:j53vh3lpr6onplmemfostk1rbf0e2nek4t@4ax.com...
> Hello,
>
> I do not have a idea, where a RTOS on a singlechip microcontroller is
> good for. I know, that it is good for making two (or more) processes
> parallel but cannot imagine, how this works. O.K, a simple example to
> make it clear. There is microcontroller and two processes shall run on
> it. The first one ANDs two intput-pins and gives the result to an
> output-pin. The second one ORs two other inputs and gives the result
> to another output-pin. If I want to make this processes parallel I
> write both commands into one program and they will run "parallel".
> What would be the way, the RTOS would make this two processes
> "parallel"?

Here are some ideas, although it is really very dependent on the 
characteristics of your application.
http://www.freertos.org/FAQWhat.html#WhyUseRTOS

-- 
Regards,
Richard.

+ http://www.FreeRTOS.org
13 official architecture ports, 1000 downloads per week.

+ http://www.SafeRTOS.com
Certified by T&#4294967295;V as meeting the requirements for safety related systems.

On Wed, 24 Oct 2007 19:21:02 GMT, "FreeRTOS.org" <noemail@address.com>
wrote:

>Here are some ideas, although it is really very dependent on the 
>characteristics of your application.
>http://www.freertos.org/FAQWhat.html#WhyUseRTOS

 Thanks, very good. That answers indeed, what I was not able to ask.
:-) A further question: Are there URLs, a forum or a group concerning
FreeRTOS on the Microchip dsPIC signalcontrollers?

>>Here are some ideas, although it is really very dependent on the
>>characteristics of your application.
>>http://www.freertos.org/FAQWhat.html#WhyUseRTOS
>
> Thanks, very good. That answers indeed, what I was not able to ask.
> :-) A further question: Are there URLs, a forum or a group concerning
> FreeRTOS on the Microchip dsPIC signalcontrollers?

Specific to FreeRTOS.org in general, rather than just the dsPIC: 
http://sourceforge.net/forum/forum.php?forum_id=382005

-- 
Regards,
Richard.

+ http://www.FreeRTOS.org
13 official architecture ports, 1000 downloads per week.

+ http://www.SafeRTOS.com
Certified by T�V as meeting the requirements for safety related systems. 

DJ Delorie wrote:

> Consider my furnace project.  Each MCU is constantly running a 1wire

OT: DJ, I am still using your wanderful GCC port for DOS (lot of
thanks for it). I never had any idea your intrests are so wide!

Thanks,
Arcady