[time-nuts] First success with very simple, very low cost GPSDO, under $8

Chris Albertson albertson.chris at gmail.com
Wed Apr 9 14:03:17 EDT 2014


On Wed, Apr 9, 2014 at 2:08 AM, Hal Murray <hmurray at megapathdsl.net> wrote:

>
> > Also any code that accesses them needs to do so with interrupts turned
> > off...  otherwise you can wind up with corrupted values.
>

Forgot if I made this point but in a GPSDO when the interrupt is caused by
the PPS, the interrupts are in effect off for 0.99999 seconds after each
interrupt.   The software can assume an interrupt will never happen less
then one second after an interrupt.  So the software does all the variable
access within millisecond after each interrupt.

These micro controllers are actually much easier to deal with than a
general purpose multi-tasking operating system.  There is far less
non-determinism.


-- 

Chris Albertson
Redondo Beach, California


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