STM32L0 Watch

PCB design, software development, STM32 learning... The watch is just a bonus for me. ;)

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STM32L051K8 microcontroller, 1.28" Sharp Memory LCD, CR2032 battery, 3D printed parts, 20mm watch strap. Heavily inspired by Max K's Chronio project here on

STL files

Zip Archive - 247.35 kB - 04/14/2017 at 02:35



Bill of materials (includes Mouser order codes)

Adobe Portable Document Format - 34.05 kB - 04/04/2017 at 15:50

Preview Download

FreeCAD project

Zip Archive - 6.77 MB - 03/30/2017 at 16:41


KiCAD project

Zip Archive - 2.70 MB - 03/30/2017 at 16:39


SW4STM32 project

Zip Archive - 5.28 MB - 03/30/2017 at 16:37


View all 6 files

  • 1 × STM32L051K8T6 Microcontroller
  • 8 × 100nF 0805 Capacitor
  • 3 × 1uF 0805 Capacitor
  • 1 × 4.7uF 0805 Capacitor
  • 2 × 10pF 0805 Capacitor

View all 20 components

  • Updated 3D files

    Ramon Imbao04/14/2017 at 02:36 0 comments

    I accidentally uploaded an earlier version of the back face. It's supposed to have this thin cutout for the PCB. Anyway, it's fixed now!

  • Printing the parts

    Ramon Imbao04/07/2017 at 03:09 0 comments

    Here's how I printed the parts for the watch. I used Slic3r to slice these. Find out more below.

    Read more »

  • Internals

    Ramon Imbao04/04/2017 at 15:24 0 comments

    Finally took the time to take a picture of the internals. Lots of photos below!

    Top cover off. Watch face held together using M3x12 countersunk screws. The black blends well. See more photos below.

    Read more »

  • Progress so far...

    Ramon Imbao03/30/2017 at 17:05 0 comments

    Currently, I would say the hardware is complete. I'd like to perhaps get the watch printed in a clear resin so people can see the inner workings of it. Black is still the sexiest.

    My files are a mess. My code is a mess as well. There are some FreeRTOS things in the code right now, but I've commented out the main thread creation portion. FreeRTOS isn't needed in this sort of thing? Well, it's still a good learning experience for me.

    I've removed the second hand to reduce power consumption. Measuring it shows it's around 0.31 mA most of the time. That would give me around a month(?) of battery life. I still need to read through and try to understand the low-power modes of the STM32L0. I think that's too big considering I'm running at 2MHz in (supposedly) low-power run mode and being in low-power sleep mode the rest of the time. Maybe I still need to reduce clock speed during sleep mode?

    Would love to implement a digital clock face, but still need to implement fonts (ongoing). I specifically chose the STM32L051 version so I have more flash memory available.

View all 4 project logs

  • 1

    3D print parts

    I printed everything except the buttons with black PLA at 0.025 (!!!) mm layer height. The buttons were printed with black TPE.

  • 2

    Populate PCB

    I started with the FPC connector since it's the most difficult one to work with and I don't have a hot air gun.

  • 3

    Insert LCD on connector

View all 8 instructions

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zakqwy wrote 04/10/2017 at 18:14 point

Yay STM32L0! I've had great luck with libopencm3, although some of the L0 stuff isn't finished (compared to the F0). If you go this route, don't forget your can easily set registers using the MMIO32(address) macro..

  Are you sure? yes | no

Ramon Imbao wrote 04/11/2017 at 03:09 point

Thanks for the tip! I'll definitely try libopencm3 out. The only reason I went with the CubeHAL is I found a book (Mastering STM32) that contained lots of examples for it.

  Are you sure? yes | no

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