I have started building a living-room-light-switch-module for the 3th time. My current device is using the DCF77. But the received signal is too weak to be reliable. I tried to correct this with software but in the end, I am not satisfied. Looking for other options I found the DS1307. This IC is a programmable clock with back-up battery. And more important, it is quite popular in the Arduino community. Lots of information available. I started to get it working with a breadboard using the computer to read the clock. The output was 00:00:00 all the time. What was wrong? After pre-setting a time, it worked perfectly. I didn’t use the library but copied some code.
