Unlocking a Tesla Model 3 with a 30-Year-Old Casio Wristwatch
Mattia Dal Ben modified a classic Casio F-91W to integrate an RFID chip capable of unlocking his Tesla Model 3.
The Casio F-91W series of digital wristwatches is one of the most iconic of all time. It’s hard to call the design stylish, but its practicality has ensured that it has remained popular over more than 30 years of production. According to the magazineIcon magazine, Casio still makes 3 million F-91W watches each year. There is a good chance you’ve owned one and maybe even still have one sitting in a box somewhere. Mattia Dal Ben modified a classic Casio F-91W to integrate an RFID chip capable of unlocking his Tesla Model 3.
The Tesla Model 3 is the best-selling electric car in all of history, which is likely due to its reasonable price, performance, styling, and “cool factor.” The Model 3 also has many really unique tech features that just aren’t found in other cars. You can, for example, use the Tesla mobile app to have your parked car startup and drive itself to your location (as long as you’re close enough). You can also use the app or a special card to unlock your Tesla Model 3, so you don’t have to carry conventional keys around. The car is unlocked by a special RFID chip in that card, and Dal Ben integrated that chip into their Casio F-91W.
In this case, the chip came from a J3A040-CL Java card from Smartcard Focus, following the recommendation from a guide written by Robert Quattlebaum. The chip was removed from the card by submerging it in a bath of acetone to separate the layers. The shape of the antenna is very important for RFID performance, so Dal Ben designed and 3D-printed a custom backing plate for the Casio F-91W watch that provided a form to wrap the wire antenna around. A small cavity in that part is reserved for the RFID chip itself. That is a little thicker than the original and the watch isn’t water resistant anymore, but it should look standard to any casual observer — especially since it still functions normally. All Dal Ben had to do was clone their Tesla key card, and now they can unlock their Tesla Model 3 using the timeless wristwatch.