Hi,
Please have a look at /opt/tinyos-2.x/tos/system/RealMainP.nc. The
execution starts from the main() and proceeds to initialize the system
and then signals Boot.booted(). If you notice interrupts are enabled just
before signalling Boot.booted().
Now your doubt reduces to the question "Is main() a intterupt handler or a
task ?".
Certainly, it is not an interrupt handler as it is the routine
that enables interrupts for the first time.
Is it a task ?
Once execution starts, tasks can be posted and main() is the point where
your system execution starts. Therefore, main() is neither a task nor an
interrupt handler.
However, I do not want group it under a separate 3rd category as execution
has to start somewhere and it starts at main().
Anybody: If I am wrong please correct me.
Regards,
Manjunath D
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On Wed, 6 Jan 2010, zheng manchun wrote:
> Hi, I'm reading the Execution Model Chapter of TinyOS programming book
> recently.
> I've got some difficulties in understanding the execution model of the
> example application Blink.
>
> As stated in the book, code is either synchronous or asynchronous.
> And execution might be either a task or an interrupt handler.
>
> When the hardware boots successfully, Boot.booted event is signaled.
> While event booted is defined as synchronous in the Interface Boot, then
> Boot.booted can not be invoked by an interrupt handler.
> Therefore, it can only be a task. Or there is a 3rd kind of execution
> (besides task and interrupt handler)?
>
> I hope that some one can help to explain the execution model of the
> application Blink for me.
>
> Thanks in advance.
>
> ===================================================
> //BlinkAppC.nc
> configuration BlinkAppC
> {
> }
> implementation
> {
> components MainC, BlinkC, LedsC;
> components new TimerMilliC() as Timer0;
> components new TimerMilliC() as Timer1;
> components new TimerMilliC() as Timer2;
>
>
> BlinkC -> MainC.Boot;
>
> BlinkC.Timer0 -> Timer0;
> BlinkC.Timer1 -> Timer1;
> BlinkC.Timer2 -> Timer2;
> BlinkC.Leds -> LedsC;
> }
> ////////////////////////////////////////////////////////////////////////////////////////////////////
> //BlinkC.nc
> #include "Timer.h"
>
> module BlinkC @safe()
> {
> uses interface Timer<TMilli> as Timer0;
> uses interface Timer<TMilli> as Timer1;
> uses interface Timer<TMilli> as Timer2;
> uses interface Leds;
> uses interface Boot;
> }
> implementation
> {
> event void Boot.booted()
> {
> call Timer0.startPeriodic( 250 );
> call Timer1.startPeriodic( 500 );
> call Timer2.startPeriodic( 1000 );
> }
>
> event void Timer0.fired()
> {
> dbg("BlinkC", "Timer 0 fired @ %s.\n", sim_time_string());
> call Leds.led0Toggle();
> }
>
> event void Timer1.fired()
> {
> dbg("BlinkC", "Timer 1 fired @ %s \n", sim_time_string());
> call Leds.led1Toggle();
> }
>
> event void Timer2.fired()
> {
> dbg("BlinkC", "Timer 2 fired @ %s.\n", sim_time_string());
> call Leds.led2Toggle();
> }
> }
> =====================================================
> --
> Thanks & Best Regards,
> Mc
>
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