One possible caveat of the epoch time calculation.
If you set a time that happens to coincide to the minute, with the subtraction of a leap second, then the until loop may never terminate.
The solution is to add 30 rather than 60 each iteration.
Of course, if your processor doesn't use NTP or some similar method to synchronise its system clock, the problem is probably moot.
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In reply to Re^2: Logical ways to calculate being within two times