It ain't pretty, but it's mine! 😄
The microcontroller used by this project is the STM32L011F4 from STM.
It features many peripherals as well as low power operation features.
This watch displays the time using four KCSA02-105 7-Segment displays from
Kingbright. They were chosen because of their small footprint. Those 7-Segment
displays are driven by the STP08DP05 serial constant current driver from STM.
In it's normal operation, the watch gets powered by a LIPO battery. It can also
be powered by an external powersource which provides 5V. The external connection
is also used to charge the internal LIPO using a MCP73831 charger IC from
Microchip. For OR-ing those two power supplies together so that the battery
is not used for powering the circuit during charging two LM66100 ideal diodes
are used. The resulting powerline gets regulated by a TLV70033 linear voltage
regulator. The resulting 3.3V are used to power the microcontroller. For the
powersupply for the display the non regulated voltage is used.