It's near Stuttgart (South-west-Germany), so shouldn't be that much of a problem.
/**
* Arduino DCF77 decoder v0.2
* Copyright (C) 2006 Mathias Dalheimer (md@gonium.net)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <MsTimer2.h>
/**
* Where is the DCF receiver connected?
*/
#define DCF77PIN 2
/**
* Where is the LED connected?
*/
#define BLINKPIN 13
/**
* Turn debugging on or off
*/
#define DCF_DEBUG 1
/**
* Number of milliseconds to elapse before we assume a "1",
* if we receive a falling flank before - its a 0.
*/
#define DCF_split_millis 140
/**
* There is no signal in second 59 - detect the beginning of
* a new minute.
*/
#define DCF_sync_millis 1200
/**
* Definitions for the timer interrupt 2 handler:
* The Arduino runs at 16 Mhz, we use a prescaler of 64 -> We need to
* initialize the counter with 6. This way, we have 1000 interrupts per second.
* We use tick_counter to count the interrupts.
*/
#define INIT_TIMER_COUNT 6
#define RESET_TIMER2 TCNT2 = INIT_TIMER_COUNT
int tick_counter = 0;
/**
* DCF time format struct
*/
struct DCF77Buffer {
unsigned long long prefix :21;
unsigned long long Min :7; // minutes
unsigned long long P1 :1; // parity minutes
unsigned long long Hour :6; // hours
unsigned long long P2 :1; // parity hours
unsigned long long Day :6; // day
unsigned long long Weekday :3; // day of week
unsigned long long Month :5; // month
unsigned long long Year :8; // year (5 -> 2005)
unsigned long long P3 :1; // parity
};
struct {
unsigned char parity_flag :1;
unsigned char parity_min :1;
unsigned char parity_hour :1;
unsigned char parity_date :1;
} flags;
/**
* Clock variables
*/
volatile unsigned char DCFSignalState = 0;
unsigned char previousSignalState;
int previousFlankTime;
int bufferPosition;
unsigned long long dcf_rx_buffer;
/**
* time vars: the time is stored here!
*/
volatile unsigned char ss;
volatile unsigned char mm;
volatile unsigned char hh;
volatile unsigned char day;
volatile unsigned char mon;
volatile unsigned int year;
/**
* used in main loop: detect a new second...
*/
unsigned char previousSecond;
/**
* Initialize the DCF77 routines: initialize the variables,
* configure the interrupt behaviour.
*/
void DCF77Init() {
previousSignalState=0;
previousFlankTime=0;
bufferPosition=0;
dcf_rx_buffer=0;
ss=mm=hh=day=mon=year=0;
#ifdef DCF_DEBUG
Serial.println("Initializing DCF77 routines");
Serial.print("Using DCF77 pin #");
Serial.println(DCF77PIN);
#endif
pinMode(BLINKPIN, OUTPUT);
pinMode(DCF77PIN, INPUT);
#ifdef DCF_DEBUG
Serial.println("Initializing timerinterrupt");
#endif
MsTimer2::set(1000, advanceClock); // 500ms period
#ifdef DCF_DEBUG
Serial.println("Initializing DCF77 signal listener interrupt");
#endif
attachInterrupt(0, int0handler, CHANGE);
}
/**
* Append a signal to the dcf_rx_buffer. Argument can be 1 or 0. An internal
* counter shifts the writing position within the buffer. If position > 59,
* a new minute begins -> time to call finalizeBuffer().
*/
void appendSignal(unsigned char signal) {
#ifdef DCF_DEBUG
Serial.print(", appending value ");
Serial.print(signal, DEC);
Serial.print(" at position ");
Serial.println(bufferPosition);
#endif
dcf_rx_buffer = dcf_rx_buffer | ((unsigned long long) signal << bufferPosition);
// Update the parity bits. First: Reset when minute, hour or date starts.
if (bufferPosition == 21 || bufferPosition == 29 || bufferPosition == 36) {
flags.parity_flag = 0;
}
// save the parity when the corresponding segment ends
if (bufferPosition == 28) {flags.parity_min = flags.parity_flag;};
if (bufferPosition == 35) {flags.parity_hour = flags.parity_flag;};
if (bufferPosition == 58) {flags.parity_date = flags.parity_flag;};
// When we received a 1, toggle the parity flag
if (signal == 1) {
flags.parity_flag = flags.parity_flag ^ 1;
}
bufferPosition++;
if (bufferPosition > 59) {
finalizeBuffer();
}
}
/**
* Evaluates the information stored in the buffer. This is where the DCF77
* signal is decoded and the internal clock is updated.
*/
void finalizeBuffer(void) {
if (bufferPosition == 59) {
#ifdef DCF_DEBUG
Serial.println("Finalizing Buffer");
#endif
struct DCF77Buffer *rx_buffer;
rx_buffer = (struct DCF77Buffer *)(unsigned long long)&dcf_rx_buffer;
if (flags.parity_min == rx_buffer->P1 &&
flags.parity_hour == rx_buffer->P2 &&
flags.parity_date == rx_buffer->P3)
{
#ifdef DCF_DEBUG
Serial.println("Parity check OK - updating time.");
#endif
//convert the received bits from BCD
mm = rx_buffer->Min-((rx_buffer->Min/16)*6);
hh = rx_buffer->Hour-((rx_buffer->Hour/16)*6);
day= rx_buffer->Day-((rx_buffer->Day/16)*6);
mon= rx_buffer->Month-((rx_buffer->Month/16)*6);
year= 2000 + rx_buffer->Year-((rx_buffer->Year/16)*6);
}
#ifdef DCF_DEBUG
else {
Serial.println("Parity check NOK - running on internal clock.");
}
#endif
}
// reset stuff
ss = 0;
bufferPosition = 0;
dcf_rx_buffer=0;
}
/**
* Dump the time to the serial line.
*/
void serialDumpTime(void){
Serial.print("Time: ");
Serial.print(hh, DEC);
Serial.print(":");
Serial.print(mm, DEC);
Serial.print(":");
Serial.print(ss, DEC);
Serial.print(" Date: ");
Serial.print(day, DEC);
Serial.print(".");
Serial.print(mon, DEC);
Serial.print(".");
Serial.println(year, DEC);
}
/**
* Evaluates the signal as it is received. Decides whether we received
* a "1" or a "0" based on the
*/
void scanSignal(void){
if (DCFSignalState == 1) {
int thisFlankTime=millis();
if (thisFlankTime - previousFlankTime > DCF_sync_millis) {
#ifdef DCF_DEBUG
Serial.println("####");
Serial.println("#### Begin of new Minute!!!");
Serial.println("####");
#endif
finalizeBuffer();
}
previousFlankTime=thisFlankTime;
#ifdef DCF_DEBUG
Serial.print(previousFlankTime);
Serial.print(": DCF77 Signal detected, ");
#endif
}
else {
/* or a falling flank */
int difference=millis() - previousFlankTime;
#ifdef DCF_DEBUG
Serial.print("duration: ");
Serial.print(difference);
#endif
if (difference < DCF_split_millis) {
appendSignal(0);
}
else {
appendSignal(1);
}
}
}
/**
* The interrupt routine for counting seconds – increment hh:mm:ss.
*/
void advanceClock() {
ss++;
if (ss==60) {
ss=0;
mm++;
if (mm==60) {
mm=0;
hh++;
if (hh==24)
hh=0;
}
}
}
/**
* Interrupthandler for INT0 – called when the signal on Pin 2 changes.
*/
void int0handler() {
int length = millis() - previousFlankTime;
if (length < 10) {
// ignore jitter
return;
}
// check the value again – since it takes some time to
// activate the interrupt routine, we get a clear signal.
DCFSignalState = digitalRead(DCF77PIN);
}
/**
* Standard Arduino methods below.
*/
void setup(void) {
// We need to start serial here again,
// for Arduino 007 (new serial code)
Serial.begin(9600);
DCF77Init();
}
void loop(void) {
if (ss != previousSecond) {
serialDumpTime();
previousSecond = ss;
}
if (DCFSignalState != previousSignalState) {
scanSignal();
if (DCFSignalState) {
digitalWrite(BLINKPIN, HIGH);
} else {
digitalWrite(BLINKPIN, LOW);
}
previousSignalState = DCFSignalState;
}
//delay(20);
}
It's that example from gonium.net » Blog Archive » Arduino DCF77 v0.2 released (with some changes that someone in the comments made, using Mstimer2 instead)
Is there a way how to know whether it is just not working or I am out of range? Because atm I cannot go outside with my Arduino. I first have to wire together my lcd and box which requires me for the light to be attached as well. So I can at soonest by Saturday test it outside.