Get the latest tech news

TOTP tokens on my wrist with the smartest dumb watch

I recently took delivery of a new replacement logic board for the ubiquitous classic Casio F-91W from Sensor Watch. The F-91W needs no introduction. It’s probably the most popular quartz watch in the world with something like 90 million total units sold.

There’s no Bluetooth radio to connect to other devices, but the combination of a lightweight tried-and-true utility watch case, with months long battery life and features you can rebuild at home is surprisingly powerful. In about an hour I was able to: replace the logic board, configure my 2FA secrets for my Google and Github accounts so I could get my most frequently used OTP codes right on my wrist and write a whole new ratemeter watchface for use as a rowing strokemeter or cadence meter! It’s a delight to hack on, and there’s even a wasm based emulator that makes testing on your computer easy and means you can play with my personal build right on this webpage →

Get the Android app