Manjunath,

>       I am observing some drift in the timers on my PC and on mica2
>       motes, is it something thing to do with hardware clocks ?

You're correct. You should assume a clock drift of 50ppm.

>       I have one more question: Using "Timer.start" interface, I
>       am not able to generate interrupts every millisecond, the least
>       possible interrupt interval is remaining at 4 milliseconds. I
>       tried with MicroTimer also but on a long run it is also not
>       accurate. Can you please suggest me something ?

Check out contib/vu/tos/lib/platform/mica2/SysTimeM.nc. In addition to
the corresponding component in the official release, this module
provides the SysAlarm interface. This is what you need.

The documentation in SysAlarm.nc does not state it explicitly, but you
have to make sure that the mote does not go to sleep between setting the
timer and firing. This is because the module relies on the internal
921600Hz clock which stops when the microcontroller sleeps.

Janos

_______________________________________________
Tinyos-help mailing list
[email protected]
https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help

Reply via email to