It is gaining time, or losing time ? If it's losing time, could it be caused by execution delays in your software ? I've seen some really bizarre things happening with my Raspberry Pi based clocks because of the chaotic behavior of Linux, and I have even seen metastability-related failures due to the way I had software scanning hardware for asynchronous events. They are fixable, but they definitely challenge your debugging skills.
BTW, the last time I saw such a thing was *yesterday*....I'm testing my RZ568m tubes for a new clock, and saw my time jump by 2 seconds, instead of the usual 1 second, because of the way in which I update the displayed time. These are often subtle bugs you dont catch while typing-in your code. On Sunday, July 18, 2021 at 12:19:21 PM UTC-7 Dekatron42 wrote: > The capacitance you cite from the datasheet is not the recommended > capacitance for the external capacitors, it is the load capacitance of the > crystal - you must check your ordering document to see which crystal you > got unless you can read the information on the crystal itself if it is > laser printed there. The load capacitance can then be used to calculate > what capacitance value you need for the two other capacitors - do a quick > test with two 22pF or 27pF capacitors if you have the crystal with CL = > 12.5pF - twice the load capacitance from the formula in the application > note: http://ww1.microchip.com/downloads/en/appnotes/91097a.pdf is > usually a good start, so if you have a lower CL value use twice that for > tests. > > Neither is the series resistance in the datasheet the value you need for > the external resistor, it is the internal resistance of the crystal itself. > You should use the value in the application note to start with, 220k - it > might be that you have damaged the small crystal by over driving it if you > used a lower value, it is explained in the application note why you need to > protect the crystal from over driving. You can read some on series > resistance and crystal selection here: > https://www.maximintegrated.com/en/design/technical-documents/tutorials/7/726.html > > . The datasheets and product documentation found on the manufacturer > website: > https://www.microcrystal.com/en/products/khz-quartz-crystals/ms3v-t1r/ > and https://www.microcrystal.com/en/products/khz-quartz-crystals/ms1v-t1k/ > do contain the equivalent circuit for the crystal similar to the one above. > > So try with twice the load capacitance for both capacitors and use the > recommended 220k resistor as in the application note and see how it behaves > - also use the pins recommended in the application note, ie CLKIN & CLKOUT. > > /Martin > On Sunday, 18 July 2021 at 20:53:32 UTC+2 MrThe50sanchez wrote: > >> Hello Again group! >> >> >> I've been testing this for a while, and I still have some delay minutes. >> This is the PCB design I'm using and components. >> >> *Components: * >> ·PIC16F1936 >> ·CRYSTAL MS3V-T1R CRYSTAL 32.768 Khz. >> ·Capacitors ( used 6.0 ; 7.0 ; 9.0 & 12.5) pF as datasheet from crystal >> recommend. >> ·Resistor value between 50/65 K ohm. >> >> *PCB Design: * >> >> This design is done following the document you guys added called: >> Microship TB097 which give's good instructions on how install Crystals to >> our pics. >> >> >> Guys, My head is gonna explote because I don't find the problem that is >> making minutes delays in 24H (About 3 mins per 24H). >> >> I'm questioning two fact's that can be making this delay: >> >> *1.* Pins connections between Crystal + Pic. In some other designs, >> crystal is attached to other pins. For example. >> >> Example A) Crystal pins connected to *PIN 9: A7/CLKIN* & *PIN 10: >> A6/CLKOUT.* >> >> Example B) Crystal pins connected to *PIN 11: RC0/T1OSO *& >> *PIN 12: RC1/T1OSI. * >> >> this make's me think that I'm connectin the crystal to wrong pins? what's >> the difference between them? >> >> *2*. Maybe I need to try better with other cap values? >> >> *3.* Software getting the count wrong? >> >> Thanks a lot guys, I really appreciate your time and help. >> >> Christopher.. >> >> >> >> >> >> El jueves, 20 de mayo de 2021 a las 21:09:01 UTC+2, Dekatron42 escribió: >> >>> Since this is a Tuning Fork type of crystal they are sensitive to to >>> much energy and might become damaged if you use them incorrectly. You >>> should read this article: >>> http://ww1.microchip.com/downloads/en/appnotes/91097a.pdf and also read >>> the Microchip application note above that Bill van Dijk suggested as they >>> both explain/discuss how to use this type of crystal. >>> >>> In this document for the PIC-processor in question: >>> http://ww1.microchip.com/downloads/en/devicedoc/41364e.pdf they also >>> mention the 91097a.pdf above as a document to read on page 71. >>> >>> /Martin >>> >>> On Thursday, 20 May 2021 at 20:40:49 UTC+2 MrThe50sanchez wrote: >>> >>>> Ei Martin! >>>> >>>> I'm using PIC16F1936 (16F family!) >>>> >>>> my connections are the following. >>>> >>>> Crystal pin 1 - RA7/OSC1/CLKIN/SEG2 >>>> Crystal pin 2 - RA6/OSC2/CLKOUT/VCAP/SEG1 >>>> >>>> >>>> I add you my pcb design (The old one) and the new one! >>>> >>>> (OLD ONE) >>>> [image: old ddesign.png] >>>> >>>> >>>> >>>> NEW DESIGN >>>> [image: new design.png] >>>> >>>> >>>> Thanks a lot! >>>> >>>> El jue, 20 may 2021 a las 16:28, Dekatron42 (<[email protected]>) >>>> escribió: >>>> >>>>> What PIC-controller is the crystal hooked up to? Did you follow the >>>>> design specifications for using the crystal you chose? >>>>> >>>>> /Martin >>>>> >>>>> On Thursday, 20 May 2021 at 16:03:55 UTC+2 [email protected] wrote: >>>>> >>>>>> All the cheap watches and clock movements seem to use the same small >>>>>> cylindrical crystal. I got many of mine by taking them out of old >>>>>> watches >>>>>> or clocks that had stopped working properly (like worn out gears in a >>>>>> clock). If you do not already have any in your junk box, you should be >>>>>> able to buy a working one from a street vendor or flea market for under >>>>>> € 5, and probably less than € 1. Also, new crystals will cost less >>>>>> than US$1 each (plus shipping and handling), so you could buy several >>>>>> and >>>>>> select the one that works the best. >>>>>> >>>>>> On Wednesday, May 19, 2021 at 11:55:42 PM UTC-7 MrThe50sanchez wrote: >>>>>> >>>>>>> ? Any recommendations of where can I get a good quality cristal for >>>>>>> my watch? >>>>>>> >>>>>> -- >>>>> >>>> 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 view this discussion on the web, visit >>>>> https://groups.google.com/d/msgid/neonixie-l/b9d34649-4fef-4fe8-a44b-8544b51dee8cn%40googlegroups.com >>>>> >>>>> <https://groups.google.com/d/msgid/neonixie-l/b9d34649-4fef-4fe8-a44b-8544b51dee8cn%40googlegroups.com?utm_medium=email&utm_source=footer> >>>>> . >>>>> >>>> -- 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]. 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