RE: [Sdcc-user] Multitasking schedulers

[Rod B. <rod_boyce@DMCWave.com>]

Ok guys,

My $0.02NZD worth would be that a pre-emptive RTOS is a little over the top
and as has been said before a task switch is very costly and I suspect
(don't flame me here if I'm wrong) required external RAM to operate
correctly.  

I would suggest an OS similar to Win3.11 that it one that does not interrupt
the currently running task.  I have written many of these for the 8051 and
variants these are very efficient as a task switch can be as simple as a
function call to the next task from the scheduler.  In the very small
targets the scheduler can be as simple as calling each task from main.  I
have used this arrangement from little 89C2051s to 87C552 & 87C592 with CAN
controller and simple task re-scheduling.

Regards,
Rod Boyce


		-----Original Message-----
		From:	Dafni & Robert Berger [mailto:da...@ho...]
		Sent:	Monday, 10 July 2000 04:13
		To:	Ioan Petrescu; sdc...@li...;
Henko Gouws
		Subject:	RE: [Sdcc-user] Multitasking schedulers

		Hi Ioan,

		I totally agree, that uCOS might be a little heavy on an
8051, but this
		depends strongly on what you want to do with it and which
8051 you are
		planning to use. You know that it is highly configurable and
if you just
		want a scheduler I think it's working just fine.

		My vision is, like to have SDCC for several microcontrollers
to have a
		common RTOS for several microcontrollers. Of course there
might be faster
		RTOSes (there is one from Intel, which is written in
Assembly) optimised or
		a specific microcontroller architecture, but I want to have
an RTOS, where I
		can write applications on top of it and I have to freedom to
use a different
		microcontroller if the one I'm using is not sufficient with
minimum effort.

		So let's first port it to the 8051 and the other micros
supported by SDCC
		and after some benchmarking let's decide if we go on with it
or not.

		regards,

		Robert

		> -----Original Message-----
		> From: sdc...@li...
		> [mailto:sdc...@li...]On Behalf Of
Ioan Petrescu
		> Sent: Freitag, 07. Juli 2000 08:43
		> To: da...@ho...; sdc...@li...; Henko
Gouws
		> Subject: RE: [Sdcc-user] Multitasking schedulers
		>
		>
		> Hi Robert,
		> I am interested in porting ucos to sdcc,I have started to
do smth,but at
		> the moment I am thinking twice which way to take,and I
wold like
		> to explain:
		> ucos-ii is great and works fine,I have the book and I have
read it and
		> experiment smth.; but for 8051  I still ask myself if it
is not too
		> complicated and huge;and I think that there are needed
many optimizations
		> to make for '51.
		> On the other side,I have the first version which appeared
in Embeeded
		> Journal and seems to me to be much shorter and more easy
to adapt to '51.
		> The main problem is how fast can the tasks be switched -
as Rene Vooberg
		> states in his port to 8052,only 10 per second - for my
immediate need is
		> very slow -,and only porting to '251 seems to be something
good,but sdcc
		> does not support '251...
		> Can you tell me what intentions do you have? I would like
to cooperate,and
		> i will be ready to do it after 15 august,when i will
finished my vacation.
		> Regards,
		> Ioan Petrescu
		>
		> At 07:54 AM 7/7/00 +0300, Dafni & Robert Berger wrote:
		> >   Hi  Henko,     various microcontrollers.  The  book
expains the
		> >internals of the RTOS and how to port it. For further
		> informations take a
		> >look at http://www.ucos-ii.com/ or contact me.  The book
is
		> approx $70 and
		> >it's worth it. There is another book called Embedded
Systems Building
		> >Blocks 2nc edition, which contains useful APIs once you
have
		> uCOS running.
		> >   Like  this you would have a microcontroller
independent framework.   I
		> >am  also very interested in porting this to SDCC. If
there are
		> other people
		> > interested in this work, let's do it together.
regards,   Robert
		> >-----Original Message-----
		> >From:  sdc...@li...
		> >[mailto:sdc...@li...]On Behalf
Of Henko  Gouws
		> >Sent: Donnerstag, 06. Juli 2000 23:01
		> >To:  sdc...@li...; Henko Gouws
		> >Subject: [Sdcc-user]  Multitasking schedulers
		> >
		> >    Hi all                 that is good value for money
and that has been
		> >tested with the    SDCC compiler.       Any help will be
		> appreciated
		> >regards   Henko
		> >
		>
		>
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		> Sdcc-user mailing list
		> Sdc...@li...
		> http://lists.sourceforge.net/mailman/listinfo/sdcc-user


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