Steve Caruso's Arduino-Powered Smart Coaster Reminds Him to Drink When He's in the Zone

Housed in a three-part 3D-printed body, this smart coaster changes color before flashing to alert the user to impending dehydration.

Developer Steve Caruso has put together an Arduino Micro-powered desk accessory designed to remind him to drink — by lighting up a 3D-printed coaster with RGB LEDs.

Built around an Arduino Micro and its Microchip ATmega328U4 microcontroller, with individually-addressable Adafruit NeoPixel LEDs providing the lighting, Caruso's project has only one purpose beyond looking good: Flashing an alert when it's time to take another drink.

"I kept forgetting to drink my water while working," Caruso explains. "I have a tendency to get so drawn into my work that I forget to do basic human things — like drink water, go to the bathroom, and eat lunch — until it's a problem."

This Arduino Micro-powered smart coaster acts as a hard-to-ignore reminder to stay hydrated. (📹: Steve Caruso)

"The Smart Coaster (well, at least as smart as an 8-bit microcontroller can be) visualizes how long it's been since I last took a drink of water by running through a gradient from white to deep blue. The more 'blue' the light is, the longer it's been. When I've gone too long without drinking, it flashes horribly until I pick up the glass."

The body of the build is a three-part 3D print, using white PLA for a centre ring, clear PETG for the base, and black TPU for the coaster part. When a glass is put on the coaster, it flexes the coaster and pushes a momentary switch — allowing the coaster to track when there's a glass and how long since it was lifted.

The code for the project has been published to Caruso's GitHub repository under an unspecified licence; thus far, he has not made the 3D print files available publicly. More information, including a suggestion to have the coaster track consumed liquid volume by weight, can be found on the Reddit thread.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire: freelance@halfacree.co.uk.
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