[Tinyos-help] what is the chance of a timer not getting fired ?

Cory Sharp cory at moteiv.com
Fri Sep 16 11:39:19 PDT 2005


Hi Maryam,

There a bug in the MSP430 timer code when a timer is set from within a 
Timer.fired event. The MSP430 timer code for TinyOS 1.x is a little too 
complicated and I've cleaned it up for the upcoming TinyOS 2.x.

The best work-around right now is to move your code from Timer.fired into a 
separate task and just post that task in your Timer.fired. This prevents 
Timer.set from being called from within Timer.fired.

The MSP430 will go to sleep if there are no pending task for the scheduler 
nor any pending hardware interrupts. Using just timers, the MSP430 will 
never go to sleep only if the events fire faster than the system can handle 
them.

Hope that helps, best,
Cory Sharp <cory at moteiv.com>


On 9/16/05, mowrang at ucsd.edu <mowrang at ucsd.edu> wrote:
> 
> Thanks Joe!
> 
> I have a question about timers:
> 
> I have a module that get called every 10sec using a timer. Each time the
> timer get fired I increment a counter by one.
> 
> Every 600sec(+some margine to let 10sec timer get fired 60 times) I
> send the value of the counter to TOSBase.
> 
> I run the program for a few hours and plot the histogram of the counter
> values and it is less than 60, 40% of the time. It can get as small as
> 12!(attached please find the histogram)
> 
> I have seen some old postings that mentioned that they didn't collect
> enough samples while calling the timer with a specific sampling rate. But
> they mentioned HOW inaccurate their samplings were.
> Can you shed some light to this problem ?
> 
> Note:
> 1)I am running this module on top of a MAC that puts nodes to sleep
> priodically.
> 2)I am using Timer interface (not TimerMilli)
> 3)I set timers one shot and start them again when the process is 
> completed.
> 
> Also I like to know how exactly the timers work when the MSP430 is sleep.
> (I didn't find any posting on this)
> 
> You said here
> (
> https://mail.millennium.berkeley.edu/pipermail/tinyos-help/2004-September/005705.html
> )
> that MSP430 goes to sleep automatically when peripherals with high speed
> clock are not active. How high this clock should be for MSP430 not to
> sleep ?
> 
> 
> thanks a LOT LOT!
> Maryam
> 
> 
> > 2.1V for the radio; the Blue LED cuts out at 2.7V which was probably
> > the problem you saw. I've run the radio down to 1.15V reliably.
> >
> > -Joe
> >
> > On 9/15/05, mowrang at ucsd.edu <mowrang at ucsd.edu> wrote:
> >> Hi
> >>
> >> I was running Telos mote to wake-up periodically using Industrial
> >> Panasonic Alkaline Batteries.
> >> When the battery voltage was 2.3v the LED that was toggeling each time
> >> that I turned on the radio, stopped toggling (I was running the code 
> for
> >> 4
> >> days so I am sure that there is nothing wrong with the code)
> >>
> >> Is the minimum of 1.8 mentioned at Telos data sheet
> >> (http://www.moteiv.com/products/docs/telos-reva-datasheet-r.pdf) only
> >> for
> >> the processor ?
> >>
> >>
> >> I have read the message at
> >> 
> https://mail.millennium.berkeley.edu/pipermail/tinyos-help/2005-January/007193.html
> >> However still I didn't get my answer for sure.
> >>
> >>
> >> Maryam
> >>
> >>
> >>
> >
> 
> 
> _______________________________________________
> Tinyos-help mailing list
> Tinyos-help at Millennium.Berkeley.EDU
> https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
> 
> 
> 
>
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