micropython/net: Add "ntptime" client from main repo.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>

Author: jimmo

micropython/net/ntptime/manifest.py

@@ -0,0 +1 @@
+module("ntptime.py", opt=3)

micropython/net/ntptime/ntptime.py

@@ -0,0 +1,48 @@
+import utime
+
+try:
+    import usocket as socket
+except:
+    import socket
+try:
+    import ustruct as struct
+except:
+    import struct
+
+# 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]
+
+    EPOCH_YEAR = utime.gmtime(0)[0]
+    if EPOCH_YEAR == 2000:
+        # (date(2000, 1, 1) - date(1900, 1, 1)).days * 24*60*60
+        NTP_DELTA = 3155673600
+    elif EPOCH_YEAR == 1970:
+        # (date(1970, 1, 1) - date(1900, 1, 1)).days * 24*60*60
+        NTP_DELTA = 2208988800
+    else:
+        raise Exception("Unsupported epoch: {}".format(EPOCH_YEAR))
+
+    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
+
+    tm = utime.gmtime(t)
+    machine.RTC().datetime((tm[0], tm[1], tm[2], tm[6] + 1, tm[3], tm[4], tm[5], 0))