[time-nuts] Raspberry Pi 4 oscillator replacement

[Poul-Henning Kamp]

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Avamander writes:

> I was wondering if anyone here has replaced the 54 MHz oscillator on the
> Raspberry Pi 4 with a GNSS-disciplined rubidium standard? An overkill
> upgrade, but is technically doable? What hardware would it take in addition
> to a GNSS-disciplined rubidium standard and a Pi 4?

This trick has gotten a lot harder over the decades.

Higher and higher PLL ratios in the chips means they demand more of their clock signal.

I dont know if the datasheet for the Rpi4 is available to check
what the requirements are, but you should probably expect to need
some kind of PLL chip to deliver a clean 54 MHz on the RPi4, locked
to your external frequency.

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