How to enter power save?

Kernel
1

nobody wrote on Wednesday, March 08, 2006:

Hi,

I would like to enter power save mode after e.g 5 second, when nothing has happend.

How to implement this in smart way?

Nothing has happend does not mean that the system has been in the idle task all the time, only that no key has been pressed, no data arived thru USB and serial port.

regards, Frank

2

nobody wrote on Wednesday, March 08, 2006:

You can place the system into sleep mode whenever the idle task runs.  This way you do not have to keep a timer to say when the last event occurs.  You just have to ensure that the sleep mode used will wake the task when an interrupt occurs (USB, Keyboard, timer interrupt, etc).

Set configUSE_IDLE_HOOK to 1 in FreeRTOSConfig.h, then write the idle hook as:

void vApplicationIdleHook( void )
{
// Set sleep mode here.
}

3

nobody wrote on Thursday, March 09, 2006:

Well, I want to be able to control the time elapsed before entering sleep mode.

So how do I ensure that the idle_hook is not running?

regards, Frank

4

nobody wrote on Thursday, March 09, 2006:

Could you use a tick hook?  A function that runs each time the context switch occurs.  From there you could reset a counter each time a function that is not the idle task runs.  Then in the idle task you could check this counter and when it reaches your timeout, it can call sleep function.

5

nobody wrote on Friday, March 10, 2006:

Yes, but not all task that are made runing by a context switch, means that anything has happend.

If I could somehow reset the counter only when a context switch to a task of certain priority is made, I think it could work.

But is that possible?

regards, Frank.

6

nobody wrote on Friday, March 10, 2006:

You can do this from a tick hook.  The priority of the task that will run at the end of the tick is given by pxCurrentTCB->uxPriority.  You can use this to do what you want (I think?).