[time-nuts] Raspberry Pi TCXO Hat

[Adrian Godwin]

Also - I'm unsure of the benefit of having a TCXO for the ethernet clock
unless it runs so hot that ethernet can't sync using the usual
uncompensated crystal. Is there some benefit I'm not seeing ?


On Sat, Nov 2, 2019 at 12:35 PM Adrian Godwin <artgodwin at gmail.com> wrote:

>
>
> On Sat, Nov 2, 2019 at 11:59 AM David J Taylor via time-nuts <
> time-nuts at lists.febo.com> wrote:
>
>>
>> Given that the path to the outside Ethernet world on both of those models
>> is
>> via a USB controller, I would expect to see very little improvement with
>> a
>> TCXO in a constant temperature environment.  Just perhaps with a RasPi-4
>> you
>> /might/ see an improvement as the Ethernet has a more direct path, but
>> that's a board where self-generated heat is greater, so the thermal
>> issues
>> might make things worse.
>>
>>
> There's a bunch of 'ifs' there though - on the early Pis, the ethernet
> chip was a major source of heat. Presumably it's a different, non-USB part
> on the Pi4 so that may or may not have changed.
>
> Does the Pi4 inherently run hotter, or is it just capable of running at a
> level where it consumes more power ? If it's under-used and maybe even
> intentionally underclocked, it might do better than earlier versions.
>
> It would at least be worth including a Pi4 running the same workload as
> the other boards in any parallel test.
>
>