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For fans, I recently ran into am interactive state chart diagram for the watch. https://casio-f91w.pages.dev/ https://casio-f91w.pages.dev/
by iamwil 3y ago
For fans, I recently ran into am interactive state chart diagram for the watch.
https://casio-f91w.pages.dev/ https://casio-f91w.pages.dev/
- rwmj 3y agoCool - has the original firmware been reverse engineered / disassembled?
- actionfromafar 3y agoMaybe it doesn’t even have firmware.
- FirmwareBurner 3y agoThere's no FW on it as a programable microcontroller would be far too expensive, it's just glue logic die under a black resin blob, optimized to the absolute bare minimum number of transistors, which you can easily reverse engineer as the die shots are now public[1], but it doesn't help you since you can't reprogram it, it's just to learn how it works. FWIW, your cheapo basic electric toothbrush without any smart features on it, has a 4-bit Swatch microcontroller[2] from the 90's, with 4K ROM, 320 bytes of RAM (flexes-biceps), for driving the motor, blinking the LED and monitoring the battery level, and this is how you write SW for it[3], and the 90's IDE & toolchain still works on Win 11 today, wild. [1] https://zeptobars.com/en/read/Casio-F-91W-OKI-quartz-watch https://zeptobars.com/en/read/Casio-F-91W-OKI-quartz-watch [2] https://www.emmicroelectronic.com/product/multi-io/em6607 https://www.emmicroelectronic.com/product/multi-io/em6607 [3] https://www.emmicroelectronic.com/sites/default/files/products/datasheets/emsd6500.pdf https://www.emmicroelectronic.com/sites/default/files/produc...
- rwmj 3y agoCalling Ken Shirriff ...
- kens 3y agoMultiple layers of metal and a 2006 date make reverse engineering this die more of a challenge then I want.
- FirmwareBurner 3y agoSorry, I didn't get what you meant, what makes 2006 a challenge for reverse engineering?
- kens 3y ago2006 is too modern for me since the features are very small. I usually reverse engineer chips from the 1970s.