Joe Hobart writes: > I can read and write the DS3231 registers with a Raspberry Pi. Unfortunately, > the RPi kernel sends time to the RTC every 11 1/2 minutes. This time is > usually > moderately accurate, but I have measured errors of up to 0.264 second, which > is > unacceptable.
That's the "11 minute mode" if you want a search term. To get rid of it you'd need to compile your own kernel (it's a compile-time option withz no run-time parameters). Only the first RTC found by the kernel should be affected, although I haven't yet confirmed this myself. I also don't know if the rasPi kernel uses the symlink from /dev/rtc (in which case you could perhaps simply point it to somewhere else) or if it picks the first RTC device that has the hctosys property set. This does not happen if the SYNC flag in the kernel timekeeping code is not set (but NTP will do that). Last but not least, if you don't use (or blacklist) the RTC driver and instead read the chip as a simple I²C device the kernel will also leave it alone. Regards, Achim. -- +<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+ Wavetables for the Waldorf Blofeld: http://Synth.Stromeko.net/Downloads.html#BlofeldUserWavetables _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
