Deadontime

The DeadOn RTC breakout board keeps the time so very accurately, with a crystal oscillator on board and even a temperature correction in case its warm heart would beat a little faster than the rest of the universe. It knows about leap years and will remember what day and time it is even when disconnected until the cell battery dies or until the year 2100, whichever comes first.

Initially, all it could provide for time was zeros:



Luckily, I saw that someone else using the same Arduino board had solved this two years ago. His wiring:

GND – GND
VCC – 3.3v
SQW – GND
CLK – 52
MISO – 50
MOSI – 51
SS – 8


The experts argue about possible seconds lost or gained over a number of days but what surprises me is the fact that the little clock will not pick up the time in stride. It accepts the time before it starts its long run, but there is a time difference. 

Imagine an athlete ready for a 100 miles run but the gun fired for the start is positioned on a distant hill. The athlete starts when he hears the gunshot, but that is not when it was fired. In the same way, I set the correct time, then compile the sketch and send it to the Arduino board which in turn informs the clock.

If I start the compilation about ten seconds before the moment it is meant to start, the time on screen more or less coincides with actual time.

And it gets nicer. When I checked the time later, the board provided the correct time for three seconds before skipping a heartbeat or two and stepping back an hour. 


I think I will just disconnect the little bugger. All by itself, it will keep a measure of time but without a wire to the rest of the world it will never know if it is correct or not and it will have no way to tell me what time it thinks it is. Or was.

A friend from Phoenix tells me "These are Heisenberg clocks. They are accurate until you look at them."




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