LED Watch
This watch was inspired by TokyoFlash watches and the movie Prospect. I wanted a watch with a retro-futuristic feel, like the scrap-tech aesthetic of the original Star Wars movies, as if it had been used, re-used, repaired, and then used again, which it kind of has.
I designed the four-layer circuit board to fit an old Citizen watch case. LEDs and other components were hand-placed and reflow soldered in a frying pan lined with sand.
The time and day of the week are displayed on 34 multiplexed LEDs for 3 seconds when a button is pressed. An M41T62 real time clock keeps time and the ATmega328p microcontroller enters deep sleep after the LEDs display the time. Everything is currently powered by a CR2016 coin cell battery.
Reading the time
Schematic
Designed in KiCad
Breadboarding
Testing connections using an Arduino Uno to program an Atmega328p microchip connected to a real-time clock and 34 multiplexed LEDs.
Printed circuit board (PCB)
A four-layered PCB was needed to accomodate the traces due to the number of LEDs on the surface. Sorting out the traces took a while by hand using KiCad free software. I tried KiCad's automated setting but it wasn't up to the task. A good meditative task, this one.
Programming
Programming is done via in-circuit serial programming (ICSP) using a jig of six pogo pins connected to an Arduino Uno as a programmer.
In-circuit serial programming (ICSP) from right to left:
1. MISO (Master In Slave Out)
2. VCC
3. Clock
4. MOSI - (Master Out Slave In)
5. Reset
6. Ground
Reflow soldering
Reflow soldering components onto PCB
Future development
I have lots of ideas for other features like a countdown timer and stopwatch but haven't yet been able to get anything working. If you happened to read this far, have an idea of what the code might look like and be interested in sharing, hit me up.
