This guide to an automated cat-feeding system is essential to modern life, especially the vacation part:
We have to work, but that doesn’t mean our cats should have to go without stinky little fish, right? Why should our economic necessities have a negative effect on their treat times? Isn’t it our responsibility to build them an Internet-enabled, Linux-based, cat-feeding device?
The system involves microcontrollers, Python, and a serial port. And fish, typically dead ones, but the design could easily be upgraded to feed from an aquarium.