TMR0 stops working

[shahidali55]

I'm actually thinking about hanging it on the wall just like it is.
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Not a bad idea. A clock does always comes in handy.
The last 2 digits were put upside down so as to get a colon from combining the two dot points on the oppositely placed standard 7-segment displays. An extra lookup table was the overhead.
If the clock is loosing or gaining time, you can adjust bres_lo reload value in the ISR.
(+.25 sec/day = bres_lo - 8 , -.25sec/day = bres_lo + 8).

Running it on a battery down to 2.1v will be the ultimate test.
My chip seems to have no problem till 2.1v. Below that the oscillator stalls and below 0.9v the ram gets corrupted.