The DCF77 library adds the ability to read and decode the atomic time broadcasted by the DCF77 radiostation. It has been designed to work in conjunction with the Arduino Time library and allows a sketch to get the precise CET time and date as a standard C time_t. The DCF77 Library download. Example sketches have been added to

1. illustrate and debug the incoming signal
2. use the library, using the setSyncProvider callback and converting to different time zones. In order to exploit all features in the library, Both the Time and TimeZone library are included.

Additional documentation and full explanations of the samples can be found in these blog posts on DCF Hardware, DCF Signal can be found here: http://thijs.elenbaas.net/2012/04/arduino-dcf77-radio-clock-receiver-library/

This package can be downloaded in different manners

• The Arduino Library Manager: see here how to use it.
• The PlatformIO Library Manager: see here how to use it.
• By directly loading fetching the Archive from GitHub:

1. Go to https://github.com/thijse/Arduino-DCF77
2. Click the DOWNLOAD ZIP button in the panel on the
3. Rename the uncompressed folder Arduino-DCF77-master to DCF77.
4. You may need to create the libraries subfolder if its your first library.
5. Place the DCF77 library folder in your arduinosketchfolder/libraries/ folder.
6. Restart the IDE.
7. For more information, read this extended manual

• If you want to have a package that includes all referenced libraries, use the pre-packaged library

1. Download the package as a zipfile here or as a tarball here .
2. Copy the folders inside the libraries folder to you your arduinosketchfolder/libraries/ folder.
3. Restart the IDE.
4. For more information, read this extended manual

##Samples

The DCF77 directory contains some examples:

This is the most basic example: it shows the raw signal coming from the DCF decoder. It will show Pulse-to-Pulse times of approximately 1000 ms and pulse widths of approx 100ms and 200ms.

This example illustrates the pulse-to-pulse time and pulse lengths coming from the DCF decoder. While the DCF specification says that pulses should be either 100 or 200 ms, you will probably see longer pulse lengths. For optimal distinction between long and short pulses use the output of this sketch to set the parameter #define DCFSplitTime in DCF77.h to (Tshort+Tlong)/2.

This example shows the binary stream generated by the pulse train coming from the DCF decoder and the resulting CET time.

This is the probably the most important example: It shows how to fetch a DCF77 time and synchronize the internal Arduino clock.

This sketch shows how to fetch a DCF77 time and synchronize the internal clock using the setSyncProvider function. Note that the loop code does not require any logic to maintain time sync. The Time library will monitor DC77 and sync the time as necessary.

This example shows how to convert the DCF77 time to a different timezone. It uses the UTC time to ensure that no ambiguities can exist. For timezone conversion it employs the TimeZone library.

The getSignal() functions allow to analyze the DCF77 signal. This helps to get the antenna in right direction e.g. Frankfurt. Example:

 bool signal = DCF.getSignal(); // Get DCF77 signal for LED     
 if (signal) { digitalWrite(BUILTIN_LED,LOW); } else { digitalWrite(BUILTIN_LED,HIGH); }

*** Using the Library ***

To use the library, first download the DCF77 library here: https://github.com/thijse/Arduino-Libraries/downloads and install it in the Arduino Library folder. For a tutorial on how to install new libraries for use with the Arduino development environment please refer to http://www.arduino.cc/en/Reference/Libraries or follow this step-by-step how-to article on installing Arduino libraries: http://thijs.elenbaas.net/2012/07/installing-an-arduino-library

If the library is installed at the correct location, you can find the examples discussed in this and the previous post under Examples > DCF77. I also added the time library to the archive for convenience.

The DCFF77 directory contains the DCFF77 library and some example sketches

• DCFSignal.pde

  This is the most basic example: it shows the raw signal coming from the DCF decoder. It will show Pulse-to-Pulse times of approximately 1000 ms and pulse widths of approx 100ms and 200ms.

• DCFPulseLength.pde

  This example illustrates the pulse-to-pulse time and pulse lengths coming from the DCF decoder. While the DCF specification says that pulses should be either 100 or 200 ms, you will probably see longer pulse lengths. For optimal distinction between long and short pulses use the output of this sketch to set the parameter #define DCFSplitTime in DCF77.h to (Tshort+Tlong)/2.

• DCFBinaryStream.pde

  This example shows the binary stream generated by the pulse train coming from the DCF decoder and the resulting CET time.

• InternalClockSync.pde

  This is the probably the most important example: It shows how to fetch a DCF77 time and synchronize the internal Arduino clock.

• SyncProvider.pde

  This sketch shows how to fetch a DCF77 time and synchronize the internal clock using the setSyncProvider function. Note that the loop code does not require any logic to maintain time sync. The Time library will monitor DC77 and sync the time as necessary.

• TimeZones.pde

  This example shows how to convert the DCF77 time to a different timezone. It uses the UTC time to ensure that no ambiguities can exist. For timezone conversion it employs the TimeZone library.

The sketch below implements the most DCF77 basic functionality. It reads the signal from pin 2, and 2-3 minutes it will update the internal clock. More information on this example can be found here:

http://thijs.elenbaas.net/2012/04/arduino-dcf77-radio-clock-receiver-library/

#include "DCF77.h"
#include "TimeLib.h"

#define DCF_PIN 2// Connection pin to DCF 77 device
#define DCF_INTERRUPT 0  // Interrupt number associated with pin

time_t time;
DCF77 DCF = DCF77(DCF_PIN,DCF_INTERRUPT);

void setup() {
  Serial.begin(9600);
  DCF.Start();
  Serial.println("Waiting for DCF77 time ... ");
  Serial.println("It will take at least 2 minutes before a first time update.");
}

void loop() {
  delay(1000);
  time_t DCFtime = DCF.getTime(); // Check if new DCF77 time is available
  if (DCFtime!=0)
  {
Serial.println("Time is updated");
setTime(DCFtime);
  }
  digitalClockDisplay();  
}

void digitalClockDisplay(){
  // digital clock display of the time
  Serial.print(hour());
  printDigits(minute());
  printDigits(second());
  Serial.print(" ");
  Serial.print(day());
  Serial.print(" ");
  Serial.print(month());
  Serial.print(" ");
  Serial.print(year());
  Serial.println();
}

void printDigits(int digits){
  // utility function for digital clock display: prints preceding colon and leading 0
  Serial.print(":");
  if(digits < 10)
Serial.print('0');
  Serial.print(digits);
}

• http://www.arduino.cc/en/Main/Libraries
• http://www.arduino.cc/en/Reference/Libraries

DCF77 is provided Copyright © 2013-2017 under LGPL License.