pcb assembly
place the oled, ds3231, buttons, and pro mini into position and wire them according to the provided guide. make sure everything is oriented correctly before soldering.
digital wristwatch
battery-powered with a super customizable screen. like an apple watch, but worse.
build instructions
hot metal part
solder each connection once everything's in place. check for solid joints and no bridging between neighboring pads. if it smells like roasting chicken, you're doing something wrong.
power
connect the lipo to the tp4056's b+ and b- terminals, and the tp4056's output to the pro mini's raw and gnd pins. double check polarity before connecting the battery.
code
connect the pro mini to your computer through the ftdi programmer, set to 3.3v. open the arduino ide, install the rtclib, adafruit_gfx, and adafruit_ssd1306 libraries, then open the provided sketch and set the date and time to whatever it is when you flash it. upload.
check the watch
power it on and confirm the screen lights up and shows the time. cycle through modes and confirm the buttons work, and check the battery readout looks sane.
troubleshooting
if nothing shows on screen, check the wiring and confirm the display address in the code. if the buttons do nothing, check the solder joints and pin assignments in the sketch.
go beyond
once it's working, try adding a stopwatch mode or swapping the pro mini for a board with bluetooth so the time can sync automatically.
your task
answer a goofy math riddle about watches and time, and submit a sketch of the watch face you want to program.