Set the time of Raspberry Pi Pico W using NTP

 While the new RPi Pico W does not have a battery to keep the RTC, it does have something the previous model was lacking, network connectivity. So using the built-in Wifi module it can figure out the time and date from a network server using the Network Time Protocol (NTP). 

It can work with it but the MicroPython binary I am using does not include a module for that at the moment (as the binary for ESP32 does) but it should not be a big deal to use that.

As usual, it was easier to say than to do, but now I have it working. Please note that if you use the Thonny program, it will adjust the Pico real-time clock without warning you. So for a while, you may think it was your code that did it when it may well it is not the case.

I just recycled some code I found but I was getting errors till I figured out the right offset for my board and timezone. You may need to tweak that to adjust it to yours.

try:
    import usocket as socket
except:
    import socket
try:
    import ustruct as struct
except:
    import struct

# (date(2000, 1, 1) - date(1900, 1, 1)).days * 24*60*60 = 3155673600
NTP_DELTA = 2208981600 #=1609459200+599522400   


# The NTP host can be configured at runtime by doing: ntptime.host = 'myhost.org'
host = "pool.ntp.org"


def time():
    NTP_QUERY = bytearray(48)
    NTP_QUERY[0] = 0x1B
    addr = socket.getaddrinfo(host, 123)[0][-1]
    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    try:
        s.settimeout(1)
        res = s.sendto(NTP_QUERY, addr)
        msg = s.recv(48)
    finally:
        s.close()
    val = struct.unpack("!I", msg[40:44])[0]
    return val - NTP_DELTA


# There's currently no timezone support in MicroPython, and the RTC is set in UTC time.
def settime():
    t = time()
    import machine
    import utime

    tm = utime.gmtime(t)
    machine.RTC().datetime((tm[0], tm[1], tm[2], tm[6] + 1, tm[3], tm[4], tm[5], 0))

This is only useful once you have connected your board to the Internet, of course. In my case, I just do:

import ntptime
ntptime.settime()

and this sets the time on the Pico's RTC properly.