Hi all.
We work on some experiments with TinyOS timers on RFA1 and RFR2 platforms. In
both cases, there is a significant time deviation from the set timer interval
and the actual time.
To analyze the behaviour, we set a timer to 5 seconds using the TimerMilliC
component by calling:
call Timer.startPeriodic( 5120 );
for this we have a constant error of 0.25 seconds per timer event. This results
in a deviation of 0.5 seconds per 10 seconds which is too much for our
application.
The deviation was measured by toggling a GPIO pin at each timer.fired event:
event void Timer0.fired() {
call Leds.led0Toggle();
}
and measuring the resulting signal via a scope. The behaviour happens with the
default TinyOS implementation of atm128rfa1 (tos/chips/atm128rfa1/timer) on
multiple platforms among them the ucmini. All show the same offset. In contrast
the same test with atmega1281-module result error <0.01s per 10s.
Do you have any idea what might cause this behaviour?
Best regards,
Elena
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