Re: [Contiki-developers] Using 2 Rtimers in a code

[Joakim E. <jo...@si...>]

Hello,

I believe that the problem comes from the picking of the next
rtimer. The RTIMER_CLOCK_LT needs to take into account the current
time to get a correct sorting when picking the next timer to
schedule since there is no static ordering of timers when time
can wrap.

We are planning on replacing the rtimer system, but I guess a fix
of this should also be done so that it is possible to use more than
one rtimer.

Try changing (in rtimer.c)

     if(RTIMER_CLOCK_LT(rtimers[i]->time, rtimers[n]->time)) {
       n = i;
     }

to something like:

     rtimer_clock_t now = RTIMER_NOW();
     if(rtimers[i]->time - now < rtimers[n]->time - now){
       n = i;
     }

This comparison would compare the actual time left before it should be 
triggered instead of "absolute" time.


Best regards,
-- Joakim Eriksson, SICS


Farnaz Moradi wrote:
> Hi,
> 
> I almost solved my problem by sorting the rtimers queue in the rtimer.c 
> code. I'm not sure whether it will work for all situation or not.
> In my code one function schedules a rtimer at time 65535. In another 
> function I set an rtimer to interrupt at times 4915, 21299, ....
> Since the rtimer for 65535 is further in time than 4915 and it has been 
> scheduled first, the interrupt for 4915 is missed and the time will 
> pass. When setting time 21299, since 4915 is still in the queue, the 
> rtimer_set function returns a value indicating that the rtimer is 
> already scheduled.
> 
> Best Regards,
> Farnaz
> 
> 
> Adam Dunkels wrote:
>> Hi,
>>
>> not sure exactly what happens from your description, but if you could 
>> post a list of clock values for which this happens, it would be helpful.
>>
>> Best regards,
>>
>> /adam
>>
>> Farnaz Moradi wrote:
>>   
>>> Hi,
>>>
>>> I am trying to use two instances of rtimer in my code. I want to set one
>>> of them using rtimer_set() function to interrupt when the clock wraps
>>> around (clock value is changed from 65535 to 0), and the other one when a
>>> random time slot arrives.
>>> I tried this scenario with netsim and it works, but when implementing it
>>> on msb430 motes, the second rtimer_set() returns value 3 which means the
>>> task is already scheduled.
>>> Could you please tell me the reason for this and what can I do to solve it?
>>>
>>> Regards,
>>> Farnaz
>>>
>>>
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