Hi, http://iki.fi/lindi/openmoko/compare-clock-sources.pl
is a simple program to compare different clock sources on freerunner. It reads NMEA data from stdin. When it detects a new second it logs the values of all clock sources. The resulting log file http://iki.fi/lindi/openmoko/clock.log shows[1] that: 1) pcf50633 rtc gains one second every 16300 seconds. 2) calypso rtc did not gain or lose any seconds during this test period 3) system time is fairly stable after I did "adjtimex --tick 9999 --freq 3419747" which corresponds gaining one second every 20912 seconds Are there any other time sources on freerunner that could be used/tested? S3C has an RTC but according to larsc it is not connected: < larsc> +hm the s3c rtc is running way to fast < larsc> +lindi-: hm, looks as if the rtc is not connected to a oscilator. so it's not usable Also, is there some existing program that could read time from pcf50633 rtc, compensate for the drift and write the result to system time? hwclock --adjust --hctosys wants to write the adjusted value back to rtc. I don't want to do this since it makes long-term monitoring of the RTC drifting difficult. best regards, Timo Lindfors [1] I used the following gnuplot commands to plot this: set xdata time set timefmt "%s" plot "clock.log" using 1:($2 - $1) title "sys", '' using 1:($3 - $1) title "pcf", '' using 1:($4 - $1) title "calypso"
