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An astronomical clock with 16 functions, with only three shift registers

Years ago I ordered 12 7-segment displays. I wanted to make a clock that displayed the time and date. But it appeared that it took too much digital IC’s to realize it. Nowadays there is arduino, and now it’s much easier to do it.

This clock can display time and date, moonage in days, sun rise and sun set, the maximum elevation of the sun, present elevation of the sun, tilt of the earth, time between sun rise and sun set, air pressure in mBar, temperature in celsius, Adjust mode to set the time and date, and set the aging register of the RTC.

This clock uses the 1 Hz SQW from the RTC as an interrupt. I made my own routines for the RTC (DS3231) so there is no need to load a RTC library

Because I am using multiplexing, the first thing I did was to connect al the a-segment of the 12 displays together. Also the b-segment, and c, d, e, f, g and dot segment.”

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