Making new version - part 1.

A project log for LED Matrix Watch

Wrist watch with monochromatic 16X16 LED Matrix inspired by retro LED watches of 70s and 80s.

Mile 09/25/2017 at 22:580 Comments

Here are two gifs showing working first prototype of Led Matrix watch. Gif on the right shows led matrix under neutral density filter (ND16) that is used in photography (got it from eBay). Plan is to cut filter into shape and put it over led matrix when in enclosure. Filter is 1.8mm thick.

Next up, you can see pictures of the new PCBs. PCBs are made by OSHPark. Some changes introduced from the first version are: 

        Led Matrix      Motherboard       PCB spacer         Backplate


There were no major problems with PCB assembly. All components reflowed nicely, except U2 that was shorted. Short was due to stencil being too thick so there was too much solder paste on the footprint. Also there were two mistakes on the PCB so they need to be corrected. PCBs on OSHPark link have all those mistakes corrected.

  1. VSEL pins of the TPS62743 were tied to the ground which gave output voltage of 1.2V and I needed them to be tied to input voltage to give output voltage of 3.3V. I disconnected traces from ground plane and connected them to input decoupling capacitor via thin enameled copper wire.
  2. MISO pin was not connected to ISP header, therefore jumper wire is needed from MCU pin 14 to ISP header pin 1. Jumper is need only while programming via ISP. After programming bootloader all programming is done via USB.

Enclosure was modeled in solidworks and ordered from (price was 15EUR for one piece). Enclosure was printed using SLS printer in black polyamide and polished after. Few pictures to test if all fits together: