As my first project with PIC microcontrollers, I chose for me DCF clock. The main reason for this was, that it was very complicated to get LED clock ( visible at the night ) with DCF synchronising possibility. The second reason, which appeared, was unavailability of alarm clock, where alarm is active in certain (working) days only. So arose the basic idea.

Because I was beginner, first I programmed clock only. After that, I presumed more complicated level and built alarm clock. Developement of project in time is possible to see from versions, which are available bellow as download links. Please, watch scheme, because versions 2.x has different one with decoder for LED display units from BCD code.

DCF clock version 2

Then I decided to decode LED segments with PIC alone and decoders (ICs) disappeared – versions 3.x. Instead of this decoder there is group of transistors to boost microcontroller outputs. Depends on the version, You can build clock only based on following scheme:

DCF clock version 3

and if You want, design may be added with 2 alarms function, then following supports scheme mentioned above:

Alarm plugin

This supplements lack of pin amount and added signals needed to alarms function.

I promissed possibility of download code, so here You are.

Version 2.1 simple decodes DCF information, compares with last state and in case of validity shows it on display: dcf_2_1.zip

Version 2.2 adds checking parity of received information: dcf_2_2.zip

Version 3.1 changes scheme (as mentioned above) and decodes information about date: dcf_3_1.zip

And the final version 3.3 adds two alarms feature: dcf_3_3.zip

Commentaries (asm and readme files) are in my native language (czech). As I mentioned, it was my start project, so I didn’t plan to publicate it (it was year app. 1996 ;-) ).