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Getting Local Time

Lesson Overview

In this lesson, we will learn how to get the local date and time from the MicroPython runtime using the standard localtime() function. We will learn about how to use the eight integers returned by the localtime() functions.

MicroPython provides a very convenient function called localtime() that will get the time from the host computer in your local timezone that you connect to via your USB cable. Your local computer has a clock and knows the time in the local timezone. This information is usually sent to MicroPython runtime when the computer is connected to the USB cable.

Note

The gmtime() function returns the time in UTC (Coordinated Universal Time) time. Use this if you want time stamps that are not dependent on time zone and daylight savings rules. For example, log files should use this function.

Sample Code

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import time

print(time.localtime())

Result

Local time returns a read-only tuple:

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(2023, 2, 28, 18, 54, 7, 1, 59)

Extracting Specific Date/Time Components

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from time import localtime

now = localtime()
print(now)

print('year:',    now[0])
print('month:',   now[1])
print('day:',     now[2])
print('hour:',    now[3])
print('minute:',  now[4])
print('sec:',     now[5])
print('weekday:', now[6])
print('day of year:', now[7])

Format of the Localtime

The format is a "8-tuple" of integers in the format (year, month, mday, hour, minute, second, weekday, yearday)

Most of the values are pretty intuitive to figure out. There are a few notes.

  1. Hour is the hour in 24-hour format. If we want to display the hour in 12-hour format we will need to do some formatting.
  2. Weekday is a numeric code that runs from 0 for Monday to 6 for Sunday.
  3. Yearday is the day of the year. January 1st is the fist day of the year so it is a 1 (not 0).

Printing Formatted Dates

Sample Code

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import time

now = time.localtime()
label = ('year', 'month', 'mday', 'hour', 'minute', 'second', 'weekday', 'yearday')
for i in range(8):
    print(label[i], ':', now[i])

print()
print("Date: {}/{}/{}".format(now[1], now[2], now[0]))
print("Time: {}:{}".format(now[3], now[4]))

Results

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year : 2023
month : 2
mday : 28
hour : 19
minute : 20
second : 26
weekday : 1
yearday : 59

Date: 2/28/2023
Time: 19:20

Label Formatting

We can also add labels to make the date and time easier to read.

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import time

days = ('Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday',
        'Sunday')
months = ('Jan', 'Feb', 'March', 'April', 'May', 'June', 'July',
          'Aug', 'Sept', 'Oct', 'Nov', 'Dec')

now = time.localtime()

label = ('year', 'month', 'mday', 'hour', 'minute', 'second', 'weekday', 'yearday')

month_number = now[1]
month_name = months[month_number]
weekday_number = now[6]
day_name = days[weekday_number]
hour_number = now[3]
if hour_number < 13:
    hour_12 = hour_number
    am_pm = 'am'
else:
    hour_12 = hour_number - 12
    am_pm = 'pm'

print()
print("Date: {} {} {}, {}".format(day_name, month_name, now[2], now[0]))
print("Time: {}:{} {}".format(hour_12, now[4], am_pm))

Label Formatted Results

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Date: Tuesday March 28, 2023
Time: 7:46 pm

Modifying the Thonny Parameters

By default Thonny syncs the host time at power up.

Thonny Default Time Settings

However, to test that our code is setting the correct local time we will need to disable this in future labs.

Thonny Default Time Settings

After we do this, the localtime() will return the number of seconds after midnight on January 1st, 2021.

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import time
print(time.localtime())


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(2021, 1, 1, 0, 0, 22, 4, 1)
This was printed 22 seconds after power up.

We will used this when we use a RTC and use the Pico "W" to sync with the NTP functions.

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from mpython import *
import ntptime
import secrets

# summary
mywifi=wifi()
mywifi.connectWiFi(secrets.wifi_ssid, secrets.wifi_pass)

print("Local time before synchronization：%s" %str(time.localtime()))
ntptime.settime()
print("Local time after synchronization：%s" %str(time.localtime()))

Result:

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Local time before synchronization：(2021, 1, 1, 0, 3, 31, 4, 1)
Local time after synchronization：(2023, 10, 16, 20, 16, 59, 0, 289)

References