Hi Elena, I do not quite remember where RTC_TIMER_HZ is actually used, maybe that is a value you can/should use when you start your timer and no kernel code is using it. The real problem is that the 62500 HZ timer is running at that speed no matter what, and nothing is going to translate that timestamp to a 32768 Hz (or any other format). TinyOS is set up to translate timer values only by power of twos (that is why TMilli is supposed to be 1024 Hz), and there is no infrastructure to change a timer by a fractional amount. So I am afraid you have to manage this time discrepancy within your time sync service manually.
Best, Miklos On Thu, Jul 6, 2017 at 10:56 AM, Elena Chervakova <elena.chervak...@imms.de> wrote: > Thank you for your fast answer. The problem is, we use sntp time > synchronisation > and get therefore wrong time stamps. Is it good idea just to change > RTC_TIMER_HZ > or it would cause more another problems? > Best, > Elena > > On 06.07.2017 10:41, Ugo Maria Colesanti wrote: >> The TimerMilliC in RFA1 is connected to the 62500Hz Symbol Counter which is >> not >> a power of 2. You need to multiply 5120 by 62500 and multiply it by 65535 >> which >> should give you 4883 after rounding. >> >> Ugo >> >> On 6 July 2017 at 10:18, Elena Chervakova <elena.chervak...@imms.de >> <mailto:elena.chervak...@imms.de>> wrote: >> >> 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 >> >> >> _______________________________________________ >> Tinyos-help mailing list >> Tinyos-help@millennium.berkeley.edu >> <mailto:Tinyos-help@millennium.berkeley.edu> >> https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help >> >> <https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help> >> >> > > -- > > Dipl.-Ing. Elena Chervakova > Embedded Software Development > System Design > > IMMS Institut für Mikroelektronik- und Mechatronik-Systeme gemeinnützige GmbH > Ehrenbergstraße 27 > D–98693 Ilmenau > > Achtung – das IMMS Ilmenau hat neue Telefonnummern: > Tel.: +49.3677.87493.58 > Fax: +49.3677.87493.15 > E-Mail: elena.chervak...@imms.de > Internet: http://www.imms.de > > Geschäftsführer: Prof. Dr. Ralf Sommer - Dipl.-Ing. Hans-Joachim Kelm > Aufsichtsratsvorsitzender: Robert Fetter > Sitz: Ilmenau - Rechtsform: Gesellschaft mit beschränkter Haftung > Registergericht: Amtsgericht Jena HRB 303807 > > Diese E-Mail enthält vertrauliche und/oder rechtlich geschützte Informationen. > Wenn Sie nicht der richtige Adressat sind oder diese E-Mail irrtümlich > erhalten > haben, informieren Sie bitte sofort den Absender und vernichten Sie diese > Mail. > Das unerlaubte Kopieren sowie die unbefugte Weitergabe dieser Mail sind nicht > gestattet. > > This e-mail contains confidential and/or privileged information. If you are > not > the intended recipient (or have received this e-mail in error) please notify > the > sender immediately and destroy this e-mail. Any unauthorised copying, > disclosure > or distribution of the material in this e-mail is strictly forbidden. > _______________________________________________ > Tinyos-help mailing list > Tinyos-help@millennium.berkeley.edu > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help _______________________________________________ Tinyos-help mailing list Tinyos-help@millennium.berkeley.edu https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
