I’m desperately trying to get a signal from a DCF77 module (http://www.reichelt.de/Bausaetze/DCF77-MODUL/3//index.html?ACTION=3&GROUPID=5727&ARTICLE=57772&OFFSET=16&WKID=0&). I think it’s wired up correctly, with +Vcc, GND and Signal to pin 2 on an Arduino Uno.
When I use the most basic example from the DCF77 library package (eg, DCFPulseLength) I can see that the internal LED on pin 13 blinks in 1 sec steps, and I believe I can see that the on and off periods are different as they should be. I can also attach an external LED to, say, pin 7 and let it blink the same way. However, as soon as I switch on the serial monitor the blinking stops and no output is produced. Why is that? As soon as I close the serial monitor the LED starts blinking again.
Other examples from the library package don’t work, no matter what I do. However, in these very basic sketch there is nothing involved from the DCF77 library.
Is there something about the Arduino serial monitor which interferes with what I’m doing?