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casio F91-W

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created  2023/05/30
modified 2023/05/31
category hardware
views    141

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

=> modification thumbnail

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 9 for the board itself and for the temp + gpio breakout pcbs (shipping for us/8 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

=> 🧵 mastodon project thread

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