Actually Maxim uses both 32K and 32.768 kHz in the same document, even paragraph:
Bit 3: Enable 32kHz Output (EN32kHz).This bit con-trols the status of the 32kHz pin. When set to logic 1, the32kHz pin is enabled and outputs a 32.768kHz square-wave signal. When set to logic 0, the 32kHz pin goes toa high-impedance state. The initial power-up state ofthis bit is logic 1, and a 32.768kHz square-wave signalappears at the 32kHz pin after a power source isapplied to the DS3231 (if the oscillator is running). Taken from the DS3231(SM) datasheet. I think it must be 32768 Hz in all cases because it is a power of 2 and can be divided down to 1 Hz. Search for "768" in both datasheets! Paolo On Sun, Feb 10, 2019 at 10:32 PM David Pye <[email protected]> wrote: > 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 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 > <https://groups.google.com/d/msgid/neonixie-l/CAOQ6x0Hm38dGSanfnvDKDKbeX6MGDZ%3DdrThb3mC2fXHvBEuhgw%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/CABj2VaYxJD6TJwuz3xV16WnJPB5icNNQk-vLLsEJttVMc%2ByOaQ%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
