Tracking The Office Coffee Machines Using Current Draw

Coffee is the lifeblood of hackers, IT workers, and apparently, IT workers who are also hackers. [Omerfarukz] is clearly the latter. He works as part of a large team spread over multiple floors, all with coffee machines, any one of which is fair game. The problem is knowing which one has coffee that is ready to pour. He needed a non-invasive way to monitor the coffee machines.

Coffee machine sensor voltage chartAfter contemplating a few solutions, he opted for one which wouldn’t offend the coffee gods. The machines use a high current to produce their heat, so he adapted some old remote control power sockets for the machines to plug into which would now monitor the current. A high current means the coffee is brewing and he knew that brewing takes one minute per cup, so the duration of the high current tells him the number of cups.

Having had no success with a current sensing transformer, he opted for an ACS712 chip, at heart a Hall effect sensor which outputs a voltage proportional to the test current. That goes to the IO pins of an ATtiny, and from there via serial to an ESP8266 and thence to Google Firebase for processing and notifying of IT workers in need of stimulation. For those wishing to partake, he’s posted the circuit on Github.

We’ve seen a few other non-invasive ways to do this monitoring. For example, there’s weighing the machines using a bathroom scale and the more manual phone-notifying alarm button.

Enhanced Coffee Brewer Knows How Much Of A Caffeine Addict You Are

Who should chip in the most to restock the community coffee supply at work is a common point of contention at some offices. This RFID infused coffee brewer called Juraduino by [Oliver Krohn] solves the issue at his workplace once and for all by logging how much is being consumed by each person and how often; quite the diplomatic hack.

[Oliver] donated his old Jura Coffee maker to his office with some added hardware cleverly hidden underneath the faceplate of the machine. An Arduino mounted within runs the show, powered through mini USB from the logic unit of the coffee maker itself. Once a co-worker swipes their RFID card over the front of the machine, a real-time clock module stamps when the coffee was requested, and then logs the amount selected by that person on a mini SD card. The data stored is sent via an additional bluetooth module to a custom app [Oliver] created with MIT App Inventor for his phone which displays the information. These details can then be exported in the form of an email addressed to everyone in the office at the end of the week, announcing definitively who can be counted on to restock the bulk of the community supplies.

Though there isn’t a link available with further documentation, [Oliver] mentions in the ‘details’ portion of his video that he’d be happy to share that information with anyone who contacts him regarding the project. You can see the Jura at work below:

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