NTP_DELTA in ntptime module is deprecated?

[dusan-zervan]

I am using NTP_DELTA to switch between summer and winter time:

from time import time, mktime, gmtime
import ntptime

try: teraz = ntptime.time()
except: return False
rok = gmtime(teraz)[0]
letny = list(gmtime(mktime((rok, 3, 31, 1, 0, 0, 0, 0))))
letny[2] -= (letny[6] + 1) % 7
letny = mktime(letny)
zimny = list(gmtime(mktime((rok, 10, 31, 1, 0, 0, 0, 0))))
zimny[2] -= (zimny[6] + 1) % 7
zimny = mktime(zimny)
if (letny < teraz and teraz < zimny):
    ntptime.NTP_DELTA = 3155673600 - 7200
else:
    ntptime.NTP_DELTA = 3155673600 - 3600

try: ntptime.settime()
except: return False

It was working for long time, but now I have flashed the latest nightly build of MicroPython and it seems like NTP_DELTA was removed? It has no effect when I set it to any value.

[dusan-zervan]

I have realized that setting RTC to local time zone is not ideal, better way is to correct time zone (especially summer / winter time) each time when displaying actual time. 🤔 However, this code is working both in old and new MicroPython:

from time import mktime, gmtime
from machine import RTC
import ntptime

try:
    ntptime.host = "sk.pool.ntp.org"
    ntptime.timeout = 5
    teraz = ntptime.time()
except:
    return False

rok = gmtime(teraz)[0]
letny = list(gmtime(mktime((rok, 3, 31, 1, 0, 0, 0, 0))))
letny[2] -= (letny[6] + 1) % 7
letny = mktime(letny)
zimny = list(gmtime(mktime((rok, 10, 31, 1, 0, 0, 0, 0))))
zimny[2] -= (zimny[6] + 1) % 7
zimny = mktime(zimny)
if (letny < teraz and teraz < zimny):
    teraz += 7200
else:
    teraz += 3600

t = gmtime(teraz)
RTC().datetime((t[0], t[1], t[2], None, t[3], t[4], t[5], 1))
return True

[dusan-zervan]

Well, as far as I understood, localtime() in MicroPython's time module is not reflecting the time zone and it is just returning the same result as gmtime(). So here is my solution (for UTC+1 = CET/CEST):

def localtime(sec = None):
    from time import time, mktime, gmtime   
    if sec == None: sec = time()
    year = gmtime(sec)[0]
    # summer - from last Sunday of March
    summer = list(gmtime(mktime((year, 3, 31, 1, 0, 0, None, None))))
    summer[2] -= (summer[6] + 1) % 7
    # winter - from last Sunday of October
    winter = list(gmtime(mktime((year, 10, 31, 1, 0, 0, None, None))))
    winter[2] -= (winter[6] + 1) % 7
    summer[6:8] = winter[6:8] = (None, None)
    sec += 3600 # UTC+1
    if (mktime(summer) < sec and sec < mktime(winter)):
        sec += 3600
    return gmtime(sec)

So I will set RTC just to UTC from NTP now.

[peterhinch]

I use the same approach of running the RTC at UTC and changing to local time for display. I wonder if it should read

    if (mktime(summer) < sec and sec < mktime(winter)):
        sec += 3600
    sec += 3600 # UTC+1

because here clocks change at 01:00:00 UTC - I don't know if the same applies to CET. Incidentally Python allows the neater

    if mktime(summer) < sec < mktime(winter):

[dusan-zervan]

because here clocks change at 01:00:00 UTC - I don't know if the same applies to CET.

That should be OK, I have set 1 hour in variables summer and winter.

Incidentally Python allows the neater

    if mktime(summer) < sec < mktime(winter):

Oh, that's great, I didn't know it, thanks! 🙂 I was programming in C++ long years and I am new in Python.

[kjm1102]

I liked your utc to local converter Dusan but I could not make the (summer[6] + 1) % 7 arithmetic work so I rejigged it

year=gmtime()[0]; winter_shift=10*3600; summer_shift=11*3600
summer=list(gmtime(mktime((year, 10, 1, 2, 0, 0, 0, 0)))); summer[2]+=(6-summer[6]); summer_utc=mktime(summer)-winter_shift                         # summer from 2am local 1st Sunday of Oct, we move from 10hrs ahead to 11 hrs
winter=list(gmtime(mktime((year, 4, 1, 3, 0, 0, 0, 0)))); winter[2]+=(6-winter[6]); winter_utc=mktime(winter)-summer_shift                          # winter from 3am local 1st Sunday of April, we move from 11hrs ahead to 10 hrs
print(winter_utc, summer_utc)
tz=winter_shift if (winter_utc<time()<summer_utc) else summer_shift; utc_tuple=gmtime(); loc_tuple=gmtime(time()+tz)                                # adjust time zone
print('tz', tz, '  utc', utc_tuple, '  loc', loc_tuple)

seems to work OK so long as Sunday is day6 of the week, so I thought I'd share.