Time Switch Controller with DCF Update

Overview

Creating an automatic control for mains heating for the house is the objective of the project which uses a PIC-controlled time switch that gets its time updated trough the DCF77 radio signal.

Explanation

Starting the heating in the morning and switching it off at night is the basic on this project with different switching points on various weekdays. There are three main parts of the microcontroller consisting of a PIC16F876A, the relays to switch the output, and the radio signal receiver. Using command line, the times are programmed through RS232 interface. Eight fully programmable outputs can be connected to relays along with 256 time points.

There is no need for backup battery since the switch points are stored in a flash memory. Changing settings when daylight saving time is applied is not an issue because the time is kept in sync with the DCF radio transmissions and it has an internal clock to bridge periods when no DCF signal is available. After a power outage, the state of outputs is restored to the programmed state as soon as the time signal has been received. The DCF signal is directly fed into the PIC.