How to Monitor Any Old Coffee Maker and Receive Brewing Notifications

A lot of new high-end coffee makers have some IoT functionality that lets you control and monitor the brewing process. But, they’re quite a bit more expensive than a basic model, and force you to buy a whole new machine. An alternative is to build a simple device that monitors the brewing status of any coffee maker and sends notifications, all without modifying the coffee maker itself.

This write-up comes from Omer Faruk Zorlu, who wanted a way to get a push notification when the office coffee maker was done brewing. His solution is ideal, because it’s simple and affordable to implement, and doesn’t require any modification to the company’s coffee machine. It relies on a principle that is true for all coffee makers, and just about anything else with a heating element: they draw a lot of current when they’re in heating up.

His device design takes advantage of that fact to determine when the coffee maker is brewing, and when it has finished. It uses an ESP8266 to monitor a ACS712 current sensor, and can be placed inline with the coffee maker’s power cord. When the brewing process is started, it sees a huge spike in current draw as the machine heats up, and then that drops off when it’s done. The ESP8266 then sends a push notification to Omer and his coworkers to let them know that the coffee is ready, just like those fancy IoT coffee machines.