So. The DS3231M datasheet specifically says it's internal clock output is 32.768kHz (https://datasheets.maximintegrated.com/en/ds/DS3231M.pdf)
whereas the other datasheet for SN ( https://docs-emea.rs-online.com/webdocs/0f6e/0900766b80f6ec88.pdf) says its' clock should be 32KHz. So the two chips are supposed to have different internal oscillator frequencies, but the datasheets suggest the other way round to what your measurements suggest. David On Sun, 10 Feb 2019 at 21:22, Paolo Cravero <[email protected]> wrote: > Hello. > One more thread on the subject of knock-off components... > > I use cheap RTC modules that use a DS3231 RTC chip (ZS-04). They are > satisfactorily accurate and I haven't had surprises in their internal > calendar. > > Today I measured the 32K output, which is supposed to be 32768 Hz, even > though the datasheet often mentions 32K ... that I would read as 32000 Hz. > > Three out of four modules measured 32699 +/- 2 Hz, and just one was at > 32768 Hz (500 MHz counter with OCXO, 10 seconds gate time and Nixies ;) ). > This would mean loosing 179 seconds a day, which is not the case. > > One more info: the three slow guys are DS3231*M*, while the 32768 one is > DS3231*SN*. I've never noticed this difference before because I use the 1 > Hz output and both have it. > > Has someone measured the 32k output of their modules and/or can help me > understand why the slow guys still keep up with the time? > > Paolo > > -- > You received this message because you are subscribed to the Google Groups > "neonixie-l" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > To view this discussion on the web, visit > https://groups.google.com/d/msgid/neonixie-l/CABj2VaZ13z8DQsoBTp0o5jei945aTdtjJ7aJ3hYq%3DkUiPJAJ_w%40mail.gmail.com > <https://groups.google.com/d/msgid/neonixie-l/CABj2VaZ13z8DQsoBTp0o5jei945aTdtjJ7aJ3hYq%3DkUiPJAJ_w%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/CAOQ6x0Hm38dGSanfnvDKDKbeX6MGDZ%3DdrThb3mC2fXHvBEuhgw%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
