Calculating Daylight Saving Time

[Heckler]

@MichelJasmin

yes I do use NTP as the starting point of my calculation and I do get the date in the following format...
Thu Jan 01 00:00:00 1970

But your example would (I believe) only work if I happened to check the time on the actual day that the DST or STD time began and only be persistent if I kept track of whether DST or STD was in effect.
However in my case I may power up the clock say on March 12 or any other day of the year and need to determine the current DST/STD status.
I could probably use your example and then check to see if the current date was before or after that date.

@Enigma (Pete)

So how do you translate this bit of code into PICbasic??

DSTStart = (31 - (((5*Year)/4)+ 4) mod 7)

Does MOD 7 mean Y= X // 7 (in your example is MOD the same as the remainder?)

At this point I think I am going to give my code a spin and see how it performs.
but great discussion
Thanks all

[enigma]

Hi Heckler


So how do you translate this bit of code into PICbasic??
DSTStart = (31 - (((5*Year)/4)+ 4) mod 7)

The whole subroutine is cut directly from my PBP program and will work as is. If you want to check it write it as a small program, set Year word variable to 2016 and debug out the start and end dates.
Cheers Pete

[Heckler]

@Pete,

I'll give it a try.
I scanned through my PBP3 manual and could not find "MOD" anywhere. It doesn't show in the reserved word list either.

From the link that Pedja089 posted...

USA starting in 2007, extended DST to
begin on the 2nd Sunday in March (Day of month = 14 - (1+Y*5/4) mod 7)
and end on the 1st Sunday in November (Day of month = 7 - (1 + 5*Y/4) mod 7).

For Europe...
DST begins on the last Sunday in March (Day of month = 31 - (4+ 5*Y/4 ) mod 7)
and ends on the last Sunday in October (Day of month = 31 - (1 + 5*Y/4) mod 7)

[gadelhas]

// Remainder (Modulus)

[enigma]

Hi

I think it depends on the manual you have, mine has MOD as a reserved word in it but an earlier version does not.
Cheers Pete

[Heckler]

If anyone is wondering...

My code above does seem to test out working.
I modified my clock code to temporarily change the time to Sun March 13 01:59:45 (15 sec before DST should start) and then watched it change from 01:59 to 03:00 as it was supposed to.

Then I changed the time to Sun Nov 06 01:59:45 and watched it change from 01:59 to 01:00 as it should.

My nixie clock checks the date and time every morning at 05:00 and then calls my routine to test if STD/DST is in effect.
So over the next year it will be tested thoroughly.

In my case the nixie display is turned off between 10 pm and 6 am but it is still keeping time.

I'll have to ponder how to implement the above calculations into my overall code as I think I would still need to do a comparison between the current date and the calculated Start/End of DST.

I can't just abandon my baby (my version of the code) as I slaved over it for several hours
and it was a great challenge (as all code writing is)

But I will ponder implementing the apparently more simpler version in the near future.

thanks everyone

[gadelhas]

Dwight

How are you getting the time? GPS?

[Heckler]

gadelhas,

from an ESP8266-01 wifi module.
Which is an amazing little wifi module that is connected to my home LAN.

check out my clock project here...
http://www.picbasic.co.uk/forum/showthread.php?t=20965

and check out my description of the ESP8266-01 module here...
http://www.picbasic.co.uk/forum/showthread.php?t=20957

The little ESP module is incredibly easy to work with and really interfaces to the PIC quite easily.

If you have more questions feel free to ask or PM me.