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]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/f86e7bfb-e8ab-4b4b-8890-f78c093223c5n%40googlegroups.com.
