This is an accurate 6 digitals clock (HH.MM.SS) for the STM8S003.

Details: https://hw-by-design.blogspot.com/2019/11/stm8-led-clock-part-1.html

The RTC is implemented in firmware. It uses a 24-bit numerically-controlled oscillator (NCO) in formware for very fine accuracy adjustment.

Mine has been calibrated to within +/- 1 sec/month (room temperature is regulated by heaters.)

Common cathode/

efficient new 7 seg display with common cathode ~20mA

Common anode display/

old Alarm clock with recycled vintage large display from cable converter + 2 small displays. ~50mA PNP anode drivers is needed. Smaller display is more efficient, so I adjust their duty cycle in firmware.

Under those 2 directories:

Hardware/ - Eagle CAD schematic, PCB

Firmware/ - STM8S003 firmware source code

Firmware written by me are licensed under GPL 3.0. It can be compiled using the free STM8 Cosmic C compiler. Additional incorporated code are under their own licenses.

Hardware is licensed under CC BY-4.0

https://creativecommons.org/licenses/by/4.0/

History:

Initial release:

• bare minimal functionality, clock trim value is hard coded.

0.1 release

• added calendar

0.2 release

• added North America Daylight Saving Time (DST) + code clean up

0.3 release

• code cleanup
• added AC alarm clock using common anode display. Sorry messy wiring only, so no PCB