I have some trouble, to get my clock running…
I’ve got a signal but no value coming in :(

maybe my debug text can help you to find an answer:

Initializing DCF77 lib
Using DCF77 pin #…
Time: 0:0:1 Date: 0.0.0
Time: 0:0:1 Date: 0.0.0
: Double flank detected
0: DCF77 Signal detected, Time: 0:0:1 Date: 0.0.0
duration: 171, appending value
at position 0
Time: 0:0:2 Date: 0.0.0
Time: 0:0:2 Date: 0.0.0
: Double flank detected
0: DCF77 Signal detected, Time: 0:0:2 Date: 0.0.0
duration: 409, appending value
at position 0
Time: 0:0:3 Date: 0.0.0
Time: 0:0:4 Date: 0.0.0
648: DCF77 Signal detected, Time: 0:0:4 Date: 0.0.0
duration: 102, appending value

thanks a lot,
Stefan

have a look here: http://gonium.net/md/2009/09/16/dcf77-radio-receiver-filter-signals/
Gwen was having similar problems, maybe his solution works for you.

-Mathias

I have recently got the DCF77 module from Conrad, and connected it to my Arduino Duemillanueve. My DCF77 module is highly unstable. I am unable to recieve one signal/second, i get anything from 4signals/second to 0signals/second. It just depends on how the module is lying on my desk.

My guess is that this module isnt able to detect DCF77 signals outside of central Europe(i live in the south of Sweden).

//Alexander

The pullup-resistor is needed because you want to supply pin #7 with a defined voltage at all times. Look at the schematic: if the DCF77 pin 3 (lets call it signal) is in an undefined state, you will receive noise on pin #7 of the arduino (lets call it receiver).

So, in order for the receiver to be in a defined state at all times, you connect it to either +5V (pull-up) or GND (pull-down). If you would do so without a resistor, this could be a short-circuit (if any of signal or receiver are at a low level). You definitely want to avoid this. (Side note: ATMega pins are tristates. In this context it means that an uninitialized pin will connect to ground – which will force all available power of your short-circuit through the ATMega. They are pretty robust – but not that robust.)

To do so you just use a resistor to limit the current that flows from 5V to GND. Usually people use with a 10k resistor. In this circuit I found the DCF77 signal reception to be better with 8k. I didn’t calculate this, I found the value through experimentation. I rarely calculate anything in my schematics, this is hobby, not work :-)

HTH,
-Mathias

I’m quite new to Arduino & Co and I was wondering if you could explain to me why exactly we need a pull-up resistor here and how you figured out that you need one with 8 kOhm?

Thanks,
Lars.

my suspicion is that the receiver is not able to pick up the signal reliably. Be careful, it needs some minutes sometimes to stabilize – so just try to leave it alone for some time. You might also try to change the value of the pullup resistor – I found that there is quite some tolerance from one receiver to another.

HTH,
-Mathias

/Dag

Now, in my house are:
Time: 22:32:38 Date: 31.1.2009

void setup(void) {
pinMode(blinkPin, OUTPUT);
// open the serial port at 9600 bps:
Serial.begin(9600);
}

Tnx for your dcf77 code! :)

Ciao!