It is one of the best-selling watches in the world, and despite being launched more than 30 years ago, the Casio F-91W continues to sell and has become an icon of digital watch design.
Now this watch that was first sold in 1989 is getting a new life, and it does so thanks to an Open Source project that allows you to replace its original components and create a watch with some interesting possibilities.
This watch is a true reference of those products prepared to last a very long time and to be difficult to use incorrectly. The original manual even states that “there is no way that the components of the unit can be damaged or malfunction by misuse of the buttons. If confusing information appears on the display, it is because the input sequence was incorrect. Please read the manual and try again”.
The truth is that this model is still available at prices around 15 dollars, but a new project gives an interesting option: that of replacing its original software and hardware to bring new functions.
This is what a developer named Joey Castillo, who has published all the data on GitHub under the project called Sensor Watch, has managed to do and reveals how to do it. First of all it is possible to replace the original board with one with a suitable form factor and a SAM L22 microcontroller that includes a small Cortex M0+.
With this hardware it is then possible to use internal software that can be modified and customized thanks to the code available in open source and that can be used for new functions.
The thing goes further: on the small board there is a 9-pin connector to install sensors such as an accelerometer, a magnetometer or a USB input/output port. There are no specific examples of what to do with these options, and the developer leaves the door open to the imagination of those who dare to try this project.