This "shim" library provides the initialization functions to use Network Time Protocol (NTP) on the ESP8266 using WiFi in the Arduino IDE. After initialization, all of the Time library functions will get their source time via NTP. The original motivation for this library was to provide a network-based real-time clock (RTC) for a Blynk application. Currently, (Sept 2016) the Blynk RTC widgit will not compile in the latest Arduino IDE and even under older (1.6.9) versions of the IDE, the time returned is UTC even when offsets are set. Also, the RTC widgit has no user interaction, so it unnecessarily occupies Blynk dashboard space which could better be utlized for widgits that interact with the user. Nevertheless, this library is not limited to Blynk and can be used in the general case.
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void NTP_UTC_Timezone(const int offset);This function sets the local timezone offset from UTC [UTC]. Note that this must be the first of these library functions called.
The header file WorldTimezones.h in this library has defines of the form UTC_* for timezone offsets across the world.
Note that fractional offsets are not supported. The offset must be a (positive or negative) integer.
void NTP_Init(void);This function sets up the network connections to one of a set of NTP servers in the United States and defines the necessary functions
so that subsequent calls to any of the Time functions (e.g. hour()) will return a time value based on the current network time (plus offset).
Essentially NTP is being used as a real-time clock (RTC).
For robustness, NTP_Init() will try all of the servers in the table of URLs until it receives a response.
If no response is ever received, then the time value will be 0.
NTPRTC.h
Declares the library functions. Mandatory.
WorldTimezones.h
C preprocessor defines for world timezones. Optional.
NTP.ino. Displays the current time on the serial console one a second. Before running, change the SSID and PASSWORD strings to those of your network. Also, change the timezone offset to your timezone.
Blynk.ino. Demo Blynk app that displays the date and time when the "Display" button is pressed.
You can get the Blynk portion of this example by scanning the QR code (Blynk Dashboard.jpg) in Blynk.
This will give you the authorization token you need to insert into the sketch along with your network SSID and password.
Go to Releases and download the latest release .zip archive. Install by using the "Sketch > Include Library > Add .ZIP Library..." menu commands in the Arduino IDE.
Of course, you may also clone this repository and manually install the files if you prefer.
The core logic of these functions is heavily based on the ESP8266 NTP example in Paul's library. This was mostly a packaging effort.
Copyright 2016 Rob Redford This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. To view a copy of this license, visit BY-NC-SA.