John Graham-Cumming’s blog: Pimping my Casio: Part Deux

2025-07-19 03:58:00
blog.jgc.org

Close to three years ago I wrote about using Oddly Specific Objects’ alternate “motherboard” to modify a classic Casio F-91W watch: Pimping my Casio with Oddly Specific Objects’ alternate motherboard and firmware. That blog post goes into the detail of swapping out the guts of the Casio and building and uploading the firmware.

Happily, Oddly Specific Objects is back with a “Pro” version of their alternative Casio internals which now features an accelerometer and an alternative LCD. The original Sensor Watch used the existing Casio LCD display but the custom LCD allows for more complicated text to be displayed on screen. It’s not a dot-matrix display so there are lots of limitations but it’s still a fun upgrade.

Also, the Sensor Watch Pro, as it’s called, requires no soldering (unlike the original version). Here’s one I prepared earlier (that is a Casio F-91W with new internals):

You can see the new display in action there showing the day as FRI. As with the original Sensor Watch there’s a browser-based emulator that uses emscripten to get the watch running on your computer. This is pretty important because flashing new firmware to the watch requires dismantling it.

Since there’s no soldering the process of upgrading your Casio is simply take it apart and put back in the parts that came in the kit (along with a small piece of metal that’s transferred from the original Casio watch to make the battery connection):

Since I bought the optional accelerometer add on it’s necessary to put in place a little piece of caption tape (you can see if covering the five pads on the image above) and the insert the accelerometer board itself:

The five vertical traces at the top are the micro USB interface used for flashing the firmware.

I modified the firmware to remove Imperial units and 12 hour clock (which I never want) and to choose my own selection of screens (I added the tally, accelerometer and light sensor screens).

The complete sequence of commands needed to build the firmware was:

brew install –cask gcc-arm-embedded
git clone https://github.com/joeycastillo/second-movement
cd second-movement
git submodule update –init –recursive
make BOARD=sensorwatch_pro DISPLAY=custom

And then to upload to the watch you connect the micro USB, click the tiny switch on the back twice very rapidly and a volume called WATCHBOOT appears on your machine. You can copy the firmware over to the watch with make install.

To run the emulator you build with emscripten:

brew install emscripten
emmake make BOARD=sensorwatch_pro DISPLAY=custom
python3 -m http.server -d build-sim

And then visit localhost:8000/firmware.html in your browser.

Source Link

Keep your files stored safely and securely with the SanDisk 2TB Extreme Portable SSD. With over 69,505 ratings and an impressive 4.6 out of 5 stars, this product has been purchased over 8K+ times in the past month. At only $129.99, this Amazon’s Choice product is a must-have for secure file storage.

Help keep private content private with the included password protection featuring 256-bit AES hardware encryption. Order now for just $129.99 on Amazon!

Unlock unlimited streaming with a free Amazon Prime trial!
Sign up today!

Help Power Techcratic’s Future – Scan To Support

If Techcratic’s content and insights have helped you, consider giving back by supporting the platform with crypto. Every contribution makes a difference, whether it’s for high-quality content, server maintenance, or future updates. Techcratic is constantly evolving, and your support helps drive that progress.

As a solo operator who wears all the hats, creating content, managing the tech, and running the site, your support allows me to stay focused on delivering valuable resources. Your support keeps everything running smoothly and enables me to continue creating the content you love. I’m deeply grateful for your support, it truly means the world to me! Thank you!

BITCOIN

Bitcoin Logo