diff --git a/adafruit_ntp.py b/adafruit_ntp.py
index bc6db0d..9dc7476 100644
--- a/adafruit_ntp.py
+++ b/adafruit_ntp.py
@@ -32,13 +32,13 @@
PACKET_SIZE = const(48)
-class NTP:
+class NTP: # pylint:disable=too-many-instance-attributes
"""Network Time Protocol (NTP) helper module for CircuitPython.
This module does not handle daylight savings or local time. It simply requests
UTC from a NTP server.
"""
- def __init__(
+ def __init__( # pylint:disable=too-many-arguments
self,
socketpool,
*,
@@ -70,45 +70,76 @@ def __init__(
# This is our estimated start time for the monotonic clock. We adjust it based on the ntp
# responses.
- self._monotonic_start = 0
+ self._monotonic_start_ns = 0
self.next_sync = 0
+ def _update_time_sync(self) -> None:
+ """Update the time sync value. Raises OSError exception if no response
+ is received within socket_timeout seconds, ArithmeticError for substantially incorrect
+ NTP results."""
+ if self._socket_address is None:
+ self._socket_address = self._pool.getaddrinfo(self._server, self._port)[0][
+ 4
+ ]
+
+ self._packet[0] = 0b00100011 # Not leap second, NTP version 4, Client mode
+ for i in range(1, PACKET_SIZE):
+ self._packet[i] = 0
+ with self._pool.socket(self._pool.AF_INET, self._pool.SOCK_DGRAM) as sock:
+ sock.settimeout(self._socket_timeout)
+ local_send_ns = time.monotonic_ns() # expanded
+ sock.sendto(self._packet, self._socket_address)
+ sock.recv_into(self._packet)
+ # Get the time in the context to minimize the difference between it and receiving
+ # the packet.
+ local_recv_ns = time.monotonic_ns() # was destination
+
+ poll = struct.unpack_from("!B", self._packet, offset=2)[0]
+
+ cache_offset_s = max(2**poll, self._cache_seconds)
+ self.next_sync = local_recv_ns + cache_offset_s * 1_000_000_000
+
+ srv_recv_s, srv_recv_f = struct.unpack_from("!II", self._packet, offset=32)
+ srv_send_s, srv_send_f = struct.unpack_from("!II", self._packet, offset=40)
+
+ # Convert the server times from NTP to UTC for local use
+ srv_recv_ns = (srv_recv_s - NTP_TO_UNIX_EPOCH) * 1_000_000_000 + (
+ srv_recv_f * 1_000_000_000 // 2**32
+ )
+ srv_send_ns = (srv_send_s - NTP_TO_UNIX_EPOCH) * 1_000_000_000 + (
+ srv_send_f * 1_000_000_000 // 2**32
+ )
+
+ # _round_trip_delay = (local_recv_ns - local_send_ns) - (srv_send_ns - srv_recv_ns)
+ # Calculate (best estimate) offset between server UTC and board monotonic_ns time
+ clock_offset = (
+ (srv_recv_ns - local_send_ns) + (srv_send_ns - local_recv_ns)
+ ) // 2
+
+ self._monotonic_start_ns = clock_offset + self._tz_offset * 1_000_000_000
+
@property
def datetime(self) -> time.struct_time:
"""Current time from NTP server. Accessing this property causes the NTP time request,
- unless there has already been a recent request. Raises OSError exception if no response
- is received within socket_timeout seconds, ArithmeticError for substantially incorrect
- NTP results."""
+ unless there has already been a recent request."""
if time.monotonic_ns() > self.next_sync:
- if self._socket_address is None:
- self._socket_address = self._pool.getaddrinfo(self._server, self._port)[
- 0
- ][4]
-
- self._packet[0] = 0b00100011 # Not leap second, NTP version 4, Client mode
- for i in range(1, PACKET_SIZE):
- self._packet[i] = 0
- with self._pool.socket(self._pool.AF_INET, self._pool.SOCK_DGRAM) as sock:
- sock.settimeout(self._socket_timeout)
- sock.sendto(self._packet, self._socket_address)
- sock.recv_into(self._packet)
- # Get the time in the context to minimize the difference between it and receiving
- # the packet.
- destination = time.monotonic_ns()
- poll = struct.unpack_from("!B", self._packet, offset=2)[0]
-
- cache_offset = max(2**poll, self._cache_seconds)
- self.next_sync = destination + cache_offset * 1_000_000_000
- seconds = struct.unpack_from("!I", self._packet, offset=PACKET_SIZE - 8)[0]
-
- self._monotonic_start = (
- seconds
- + self._tz_offset
- - NTP_TO_UNIX_EPOCH
- - (destination // 1_000_000_000)
- )
-
- return time.localtime(
- time.monotonic_ns() // 1_000_000_000 + self._monotonic_start
- )
+ self._update_time_sync()
+
+ # Calculate the current time based on the current and start monotonic times
+ current_time_s = (
+ time.monotonic_ns() + self._monotonic_start_ns
+ ) // 1_000_000_000
+
+ return time.localtime(current_time_s)
+
+ @property
+ def utc_ns(self) -> int:
+ """UTC (unix epoch) time in nanoseconds. Accessing this property causes the NTP time
+ request, unless there has already been a recent request. Raises OSError exception if
+ no response is received within socket_timeout seconds, ArithmeticError for substantially
+ incorrect NTP results."""
+ if time.monotonic_ns() > self.next_sync:
+ self._update_time_sync()
+
+ return time.monotonic_ns() + self._monotonic_start_ns
diff --git a/examples/ntp_set_rtc.py b/examples/ntp_set_rtc.py
index e4f331b..e0be6f9 100644
--- a/examples/ntp_set_rtc.py
+++ b/examples/ntp_set_rtc.py
@@ -3,6 +3,7 @@
"""Example demonstrating how to set the realtime clock (RTC) based on NTP time."""
+import os
import time
import rtc
@@ -11,15 +12,19 @@
import adafruit_ntp
-# Get wifi details and more from a secrets.py file
+# Get wifi AP credentials from a settings.toml file
+wifi_ssid = os.getenv("CIRCUITPY_WIFI_SSID")
+wifi_password = os.getenv("CIRCUITPY_WIFI_PASSWORD")
+if wifi_ssid is None:
+ print("WiFi credentials are kept in settings.toml, please add them there!")
+ raise ValueError("SSID not found in environment variables")
+
try:
- from secrets import secrets
-except ImportError:
- print("WiFi secrets are kept in secrets.py, please add them there!")
+ wifi.radio.connect(wifi_ssid, wifi_password)
+except ConnectionError:
+ print("Failed to connect to WiFi with provided credentials")
raise
-wifi.radio.connect(secrets["ssid"], secrets["password"])
-
pool = socketpool.SocketPool(wifi.radio)
ntp = adafruit_ntp.NTP(pool, tz_offset=0, cache_seconds=3600)
diff --git a/examples/ntp_simpletest.py b/examples/ntp_simpletest.py
index a3f1b70..59b88bb 100644
--- a/examples/ntp_simpletest.py
+++ b/examples/ntp_simpletest.py
@@ -3,6 +3,7 @@
"""Print out time based on NTP."""
+import os
import time
import socketpool
@@ -10,15 +11,19 @@
import adafruit_ntp
-# Get wifi details and more from a secrets.py file
+# Get wifi AP credentials from a settings.toml file
+wifi_ssid = os.getenv("CIRCUITPY_WIFI_SSID")
+wifi_password = os.getenv("CIRCUITPY_WIFI_PASSWORD")
+if wifi_ssid is None:
+ print("WiFi credentials are kept in settings.toml, please add them there!")
+ raise ValueError("SSID not found in environment variables")
+
try:
- from secrets import secrets
-except ImportError:
- print("WiFi secrets are kept in secrets.py, please add them there!")
+ wifi.radio.connect(wifi_ssid, wifi_password)
+except ConnectionError:
+ print("Failed to connect to WiFi with provided credentials")
raise
-wifi.radio.connect(secrets["ssid"], secrets["password"])
-
pool = socketpool.SocketPool(wifi.radio)
ntp = adafruit_ntp.NTP(pool, tz_offset=0, cache_seconds=3600)
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