Jean-Yves,

> Does any of you has an idea of a multitask kernel (2 tasks should cover
> most applications) without using interrupt facilities in order to be put
> on a PIC 12C509 for example ?

Are you looking for a commercially built kernal?  Or are you looking
for ideas on how to structure code to multi-task?

If you are asking for ideas, we need to know more about what the tasks
will do.  To multi-task without interrupts, you will end up with a
main loop which calls the tasks, or portions of them.  The taks must
be structured to run for some time, then let another task run. And
there will usually be some other code to coordinate any shared
variables or communication between the tasks.

Two important things are to know how the tasks must communicate, and
whether there is hardware that they must share.  Also, it is
important to know what latency is acceptable, that is, how long can
one of the tasks be stopped before it fails?

------------
Barry King, KA1NLH
Engineering Manager
NRG Systems "Measuring the Wind's Energy"
Hinesburg, Vermont, USA
barry@nrgsystems.com
"The witty saying has been deleted due to limited EPROM space"