[kwolf1909] developed an ATtiny-based decoder for DCF77, which broadcasts a time signal to Europe on 77.5 kHz.

[kwolf1909] developed an ATtiny-based decoder for DCF77, which broadcasts a time signal to Europe at 77.5 kHz. The circuit processes the bitstream from the receiver and displays the time on an I2C screen.

The receiver is not included in the project. It features a button that switches display modes with a short press and resets DCF77 with a long press. If an ATtiny with enough pins is used, an external temperature sensor and real-time clock module are also supported.

Why it matters

This project offers a practical example for clock applications that do not rely on a network connection by making standard time information distributed by radio usable with a small microcontroller. The choice of ATtiny shows that basic functions can be handled with limited hardware, while I2C screen support makes the output directly visible. Support for a sensor and real-time clock via additional pins allows the same design to be adapted to more extensive setups, such as displaying temperature or retaining time information with a separate module. However, because the receiver is not included in the project, those wishing to build the system must separately obtain hardware that provides the DCF77 bitstream and ensure compatibility. The main unresolved issue is how the connection and software requirements of additional modules will be met as the number of pins increases across different ATtiny options.