casio F91-W
created 2023/05/30 modified 2023/05/31 category hardware
the casio f91-w is the classic inexpensive digital watch from casio used for bomb-making, known for its
singular backlight led
singular daily alarm
stopwatch
very low-power
simplicity 😊
longterm time accuracy
ability to be easily modded 🤩
modification
sensorwatch
sensorwatch makes a board replacement for the watch that makes use of all the existing parts of the watch -- so you get an ARM processor with full control over display segments and gpio extensibility, retaining the battery life and good timekeeping of the classic
sensorwatch
it retails $39 for the board itself and $4 for the temp + gpio breakout pcbs (shipping for $8 us/$18 worldwide)
n-o-d-e
very inceteful resources on f91-w modding that summarizes a lot of common and some unique mods
datarunner
misc. watch mods
datarunner
front acrylic replacement
embedded nfc/rfid antenna
3d printed insert for micro-sd
experiment to embed a micro-sd usb reader
replacing the backing film of the lcd
experiment to replace piezo with vibration motor
misc. watch mods
putting transparent colored polymide tape on lcd to change background color
putting polarized sheet on to lcd to invert colors
removing the backing film of the lcd and painting the lcd white
replacing the backlight (and adding a secondary on the other side)
my own
i attempted to 3d print a larger back for the watch that could house an attiny85, a female usb c port, and gpio headers; the idea being it could act as a portable rubber ducky or extended with a module with a battery for the microcontroller to do stuff and thing
it failed after i could not successfully solder tiny wires free hand without a protoboard AND keep the connections from eventually short-circuiting or breaking completely :c