Lpc2000

guillermoprandi <yahoo.messenger@...> schrieb am Thu, 06 Oct 
2005 12:37:46 -0000:


> I'm looking for some
> (free if possible) multithreaded OS that would handle the transition
    ^^^^
Seems no-one wants to pay for SW anymore ?!

> to the processor's idle state on traditionally blocking calls like
> fread() and fwrite(), expecting to wake up on interrupt; also, some
> preemptive multitasking should be supported, in case some thread
> enters an exceptionally long calculating task. Probably there's no
> known OS that directly supports this;

Any pre-emptiv RTOS out there supports this (non-free Sciopta e.g.
(my companies one)).

All the OS must provide is a way to know when it is idle, which is either
a OS hook or a special process.

Then it is up to you to enter low-power mode, means it depends largely
on the uC you use.

Some (like Sciopta and OSE Epsilon) even allow you to power-off your 
application given you preserve the current state (non-volatile RAM).

This technic is used e.g. in some BlueTooth chips, where the ARM cpu
is 70% of the time off.

-- 
42Bastian Schick