~~NOTOC~~
{{ :led_clock:dsc02564.jpg?300|wall clock with LED clock add-on}}
The LED clock is an add-on for round wall clocks. The purpose is to have LEDs on the circumference of the clock to show the progress of the time using coloured light.

==== requirement ====

For that you will need:
  * WS2812b RGB LEDs strip (long enough to go around the clock)
  * development board with a STM32F103 micro-controller and 32.768 kHz oscillator for the Real Time Clock (such as the blue pill), or external RTC module such as the I2C DS1307 (only supported in the [[https://git.cuvoodoo.info/kingkevin/led_clock-old|old firmware]])
  * coin cell battery to keep the RTC running (optional)
  * GL5528 photo-resistor to adjust the LED brightness (optional)
  * DCF77 to automatically update the time (recommended)

More details about the project can be found in the [[https://git.cuvoodoo.info/kingkevin/stm32f1/src/branch/led_clock/README.md|README]].\\
The code for the micro-controller is available on [[https://git.cuvoodoo.info/kingkevin/stm32f1/src/branch/led_clock|git]].
It includes the script to compile the code, flash the firmware, and generate the source documentation is included.\\
A release with sources, compiled firmware, and documentation is available {{:led_clock:led_clock-release.tar.bz2|here}}.

Here I will only put picture to show how it looks like.

==== add-on ====

{{  :led_clock:setup-dcf.jpg?300|LED clock add-on}}
Here is the LED clock add-on:
  - blue pill development board with STM32F103 micro-controller
  - tiny RTC I2C module with Maxim DS1307 RTC IC (not used in the end)
  - CR2032 coin cell battery (to keep the internal RTC running)
  - DCF77 receiver module (salvaged from a radio clock)
  - USB to power board and LEDs
  - ST-Link V2 (clone) to program the micro-controller
  - USB to UART converter to set time and debug
  - WS2812b LED strip
  - GL5528 photo-resistor

==== clock integration ====

Here how it is integrated in the wall clock:

{{:led_clock:dsc02551.jpg?300|}}
{{:led_clock:dsc02552.jpg?300|}}
{{:led_clock:dsc02553.jpg?300|}}
{{:led_clock:dsc02554.jpg?300|}}