[time-nuts] Features of a Precision Clock?

[Brooke Clarke]

Hi James:

Can you point me to an example Bulletin C?

Have Fun,

Brooke Clarke

w/Java http://www.PRC68.com
w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml
http://www.precisionclock.com



James Maynard wrote:

>On receipt of Bulletin C, can you arm this clock to display the upcoming 
>leap second? That's a feature that I would desire.
>
>Brooke Clarke wrote:
>  
>
>>Hi:
>>
>>I've got the Precision Clock to work and have some questions about the 
>>priority of the features.  As it is now the clock allows user selection 
>>of the input frequency at power up that determines the instruction clock 
>>for the PIC micro controller.  The choices are 2.5, 5, 10 or 20 Mhz.  
>>The clock displays on line one HH:MM:SS and on line two Day of Week, 
>>YYYY, Mon, Day of Month.  The leap year testing uses the 4, 100 and 400 
>>year rules and so you can determine the day of the week for any Georgian 
>>calendar (1583 onwards) date.
>>
>>Setting is by means of 4 buttons, Right, Left, Increment, Decrement.  
>>This is very intuitive and quick.  During setting the clock continues to 
>>keep time.  Also a new data field to the right of the seconds appears as 
>>4 hex digits to allow moving the LED/1 PPS output pulse in 1 ms steps. 
>>
>>If the input frequency fails then all the fields that can blink do blink 
>>and the clock stops.  Pressing and holding Right or Left for a few 
>>seconds clears the blinking and restarts the clock using the input 
>>frequency that was selected at power up.
>>
>>For more see:
>>http://www.pacificsites.com/~brooke/PRC68COM.shtml#PC3
>>
>>Now for the possible next features to be added.  It would be nice to get 
>>some feel for how important they are:
>>
>>(1) Synchronize the 1 PPS output rising edge to be near a 1 PPS input 
>>pulse on a one time basis (the 1 PPS edge will have an error of a few 
>>instruction cycles which are each 4/Fin long).  If this was done the 
>>manual setting would be removed.
>>
>>(2) Add another mode of operation where the clock runs on it's internal 
>>RC oscillator and the timing is determined by an external 1 PPS that 
>>needs to always be connected.
>>
>>(3) Add a backup Real Time Clock with it's own coin cell battery to 
>>allow using the clock in a portable application and allow the clock to 
>>be shipped while running.  The chip has a 0.1 ppm aging trim capability 
>>and there could be a provision to automatically trim it when one of the 
>>above precision input frequencies is applied for maybe a day.  Then when 
>>the input frequency is disconnected the clock would continue to tell the 
>>time.  There are also many options for alarms.
>>
>>(4) Other displays such as fractional Julian Day number, fractional 
>>Modified Julian Day number. sidereal time, or ??? 
>>
>>I don't think there's enough memory for all of the above, probably only 
>>one or two of them so I'm hoping to get some input on the priorities.
>>
>>Have Fun,
>>
>>Brooke Clarke
>>
>>    
>>
>
>
>  
>