Re: [Amforth-devel] Ultra Low Power operation

[Matthias T. <mt...@we...>]

Hi,


> Hi, as the amforth will not be a subject of power computing let me
> ask the experts following:
> 1. would it be possible to create a mechanism where amforth/atmega
> will be run on _very_ low power - basically powerdown or sleep

I did not yet implemented it, but the strategy should be strait
forward (as far as I understood the sleep mode section):

1) use the multitasker
2) setup an idle task which does nothing but enter the right
   sleep mode
3) whenever an interrupt is able to wake up the controller, the
   processing will continue. Sooner or later the multitasker will
   re-call the sleep task and everything is quiet again.

> 2. the rx will be connected to an additional interrupt pin

The usart interrupts can trigger the sleep-end condition itself.

> 3. after receiving a character it will issue some message on state -
> that everything is ok (e.g. none reset or power-off occured) and it
> will start to communicate with us in a normal way..

After leaving the sleep mode, the controller continues just like
if nothing has happened. Until the next sleep instruction is called
(there is a stupid wrapper word in the dictionary which does nothing
but call the SLEEP intruction.)

> 4. when not communicating with host for e.g. 10sec, or none tasks to
> accomplish, it will go to low power state again..

why wait? whenever the idle task is activated, the main task has nothing
to do at all.

Some googling revealed some pitfalls (connected usart devices or
connected programming tools like debuggers may prevent the power save
effects) however. in German:
http://www.mikrocontroller.net/articles/Sleep_Mode

I'd like to hear if it works. If it doesn't of course too

Matthias