LED Clock: Daylight Savings Time

I hadn’t even considered DST until just now, when I dug out my “eBay special” logic analyzer to see if I could figure out how it works, and noticed that its clock is an hour off.

The timekeeping chips I’m considering don’t (as far as I know) have any facility for DST. However, they do record month, day, and day of week. If I can find the specification for when DST starts and ends, I should be able to increment the hour by 1 during DST, and use the straight hour value during DWT. I’m talking about translating in the display software–I don’t want to monkey with the actual time setting on the RTC if I don’t have to.

Since the clock won’t display the date (at least as currently envisioned), the translation is pretty easy–literally just add 1 to the hour, without worrying about a carry to the day and month fields.

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