[time-nuts] FE-5680A GPS discipline board on sale now

[Nick Sayer]

All the more reason to just observe the log and manually select the value to burn in, IMHO. If you happen to see that the discipline is alternating between adjacent values, then you can "de-dither" by adding back the two lost resolution bits and selecting the correct low-bits by interpolation. 



Sent from my iPhone

> On May 21, 2016, at 3:00 PM, Chris Albertson <albertson.chris at gmail.com> wrote:
> 
> You SHOULD never have to write very frequently to the EEPROM.  As long at the 5680 is connected to the GPS you don't have to write to the EEPROM at all.  Only time you'd need to write is just before it is disconnected.  Will you do that even three times a week.
> 
> The unit that discipline the 5680 would have a "shutdown" button on it, when pressed it would turn itself off but just before would write the best EFC value to the EEPROM.   That would likely be the average EFC over the last several days.  If a 5680 is used in a disconnected hold over mode you's like it to be programmed with an EFC value that will work best over a long hold over.  This might not be the same EFC value that was sent to the 5680.
> 
>> On Sat, May 21, 2016 at 8:37 AM, Nick Sayer via time-nuts <time-nuts at febo.com> wrote:
>> You're right. The EEPROM of concern is the one in the 5680. Since they're used, you have no idea how many writes they've already endured (likely a low number), and they're quite old.
>> 
>> Sent from my iPhone
>> 
>> > On May 20, 2016, at 3:20 PM, paul swed <paulswedb at gmail.com> wrote:
>> >
>> > Mark
>> > By todays standards yes. But they were not that great 10 years ago.
>> > So I may be crossing wires. I am speaking off the eeprom in the 5680 and I
>> > think you are speaking to the one in the AVR. That would be of the modern
>> > type.
>> > Regards
>> > Paul
>> > WB8TSL
>> >
>> >> On Fri, May 20, 2016 at 5:31 PM, Mark Sims <holrum at hotmail.com> wrote:
>> >>
>> >> I think the EEPROM in AVR chips is rated at 100,000 writes.   Several
>> >> people have tested them and most found they would survive at least 5
>> >> million writes... YMMV, of course.
>> >> ------------------------
>> >> One write every 24 hours is still under
>> >> 10K writes in a reasonable lifespan for a GPSDO. It’s a rare eeprom that
>> >> is rated that low.
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> 
> 
> -- 
> 
> Chris Albertson
> Redondo Beach, California