I´m using a PCF 8583 I2C RTC for one of my projects (i´m not a professional, just an amateur). The clock delays about an hour per day, which I find unacceptable.
I´m using a 32768 Hz, 12.5 pf, 50 Kohm crystal with the RTC. Acording to the datasheet, the capacitance is OK (5 min, 20 max, 10 typical), but the resistance is a bit high. They don´t provide minimum nor typical values for that, but state a maximum 40 Kohm for the crystal.
Can this be the cause?
I personally think something else must be wrong. I used the same components and program code for another project, and it is not as bad as this one (it also delays, but about 3 minutes per day).
My last effort was to add a wire connecting the crystal package to ground. It improved, but not enough.
Any thoughts on how to improve accuracy?