If it is running slow, reduce the value of the capacitor.
There are only the markings as shown in the photo of post #11.Do you know the manufacturer of the crystal? Check for a logo.
The HC49U crystal you originally tried appears to be from Comtec-Crystals of Germany, and is definitely 32.768MHz. I've attached the data sheet (I hope!)There are only the markings as shown in the photo of post #11.
I got a tuning fork crystal and swapped it for the other one. With 15p and 20p it starts immediately. I may try some other values to see when it stops.
After swapping the MHz crystal for the kHz crystal I experimented with several values and too found that it's actually quite tolerant. The phase of the moon doesn't enter into it after all!I have to admit that if I'm at work, I use 22pF, because there is a big reel of 1206 sized 22pF NPO capacitors which was bought before I started the job; and if I'm making something at home I use 15pF (because I have a big reel etc. etc.)
I've never found one that failed to oscillate, except when I added them to a DS1338 which already has them built in.
Crystals are mechanical resonators, so the higher the resonant frequency the smaller they are. . . . .After swapping the MHz crystal for the kHz crystal I experimented with several values and too found that it's actually quite tolerant. The phase of the moon doesn't enter into it after all!
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by Robert Keim
by Jake Hertz