Turning an Old Smartwatch Into a '70s-Style Desktop Notification Display
Pierre Muth has transformed a broken Garmin watch into a fun little desktop display that shows phone notifications in an interesting format.
A broken watch
The Garmin Forerunner series of smartwatches was introduced nearly two decades ago back in 2003, making them an early precursor to the modern assortment of fitness trackers, personal assistants, and perhaps most importantly, a quick way to see notifications with a brief glance. In more recent years, the company has released other lineups of watches, including the Vivosmart series. Pierre Muth is also a fan of small electronics, and after a brief attempt and subsequent failure at building a miniature notification display using an ESP32, he instead thought to repurpose a Garmin Vivosmart 3 that had a broken display into a desktop notification system.
Decoding signals
After determining that the watch's internals were still functioning, Muth's first goal was to figure out how to best attach a brand new screen that could still be controlled by the Vivosmart 3's microprocessor. He discovered that the watch contained a very basic 128x64-pxiel OLED screen, and was able to view the SPI data going towards it thanks to a logic analyzer. Once the bits had been decoded, he could finally see how the arrangement of 1's and 0's produced the resulting raster image.
Replacement hardware
To replace the broken OLED screen, Muth went with a vacuum fluorescent display (VFD), which uses a phosphor-coated anode and somewhat high voltage to produce a bright glow, akin to how a CRT television works. Because the OLED receives data using the SPI bus while the VFD communicates over UART, a single PIC18F57K42 microcontroller was added between the watch's PCB and the new VFD screen to translate the signals.
Viewing notifications
The final step of this project involved designing a new enclosure with the help of Fusion 360 in the style of an old 1970's television set. The result, in the words of Muth, was an "absurd notifier" that delivers instant notifications from the user's phone, even if the entire thing takes up a lot of desk space. To see more about this project, you can read its write-up here on Muth's blog.