Monitoring a coffee pot with an Arduino

coffee graph

Coffee has always been an important part of the internet; the first webcam ever was in the Trojan Room of the Cambridge University Computer Laboratory to monitor the contents of a coffee pot. Now, instead of webcams, we have Arduinos and a bathroom scale. Not particularly similar to a webcam, but more than enough to keep track of how much coffee is currently available at DoES Liverpool.

Being a techy workshop/studio, coffee is always in short supply at DoES Liverpool. Instead of getting up and checking the pot, [Patrick] thought it would be a good idea to monitor the contents of a coffee pot online. He’s doing this with a bathroom scale underneath the coffee machine connected to an Arduino Ethernet module. By measuring the weight of the coffee pot and subtracting the known empty weight, [Patrick] can get a pretty good idea of how much coffee is left in the pot, and how long the coffee has been sitting there.

The data from the Arduino is fed to an Xively feed that displays the current status of the coffee machine on any computer with an Internet connection. Far more sophisticated than the first webcam ever, and a very useful tool for everyone at DoES Liverpool.

25 thoughts on “Monitoring a coffee pot with an Arduino

  1. You can actually do this without the scale, up to a certain extent. The coffee in an ordinary pot usually is heated with a heating plate underneat it. This heat plate usually is controlled by a bang-bang-controller, that is, if the coffee is colder than X degrees, the heater turns on, if it’s warmer than Y degrees, the heater turns off again. Now, the heater will always put X watts of power into the coffee. It needs to heat up a varying amount of coffee, though, and half a pot full is more easily heated up than a full pot. So, by measuring the amount of time the heater pulls electricity, you can see how much coffee is left. If you’re measuring electricity anyway, you can also see when a new pot is brewed, so in the end, all you need is a simple power meter in the power line of the coffee machine and you can figure out all kinds of state. I used this to turn off the coffee maker if it was empty when i still was a student; worked like a charm.

    1. That’s a really interesting approach. I have been getting round to adding current sensing — to measure brewing and 1 or 2 plate heating — but I hadn’t thought about timing the determine the contents. I wonder how quick the update rate would be and whether it might make a good reference reading to zero out any drift in the strain gauge tare point.

    1. I’m wondering if HaD is paying big bucks in royalties to use that cartoon character?

      If any editors read this comment, I personally think an application “theme” like this is a great idea if used occasionally. It works great for Google and I think it can work really well here.

      But using some big brand image really makes this feel more like some lame idea a middle-level manager in a big corporate structure got from a focus group, rather than HaD’s tradition “grassroot feel” of showcasing hacks mostly make by determined individuals.

      1. i really doubt they care enough seeing how he is all over the internet for everything and HAD is not really making money off of it making a copyright claim hard

  2. Yuck, coffee.

    Drink of the devil.

    I love chocolate but find it disgusting that certain chocolate makers put coffee in some of them.

  3. 3 suggestions, first when the weight drops below empty zero (the carafe) is removed take a “mug shot” (that’s a joke son, I made a funny) with a webcam in case somebody doesn’t refill an pot (or to see who is a caffeine freak). Second put a strain gauge on to keep people from putting the sugar on top of the machine to fool it and third add a timer so 20 minutes after the display will tell people the coffee just isn’t feeling fresh anymore.

    1. Cool. but you need to put some coffee on…

      ######################################
      #                                    #
      #   )  Coffee telnet v.5             #
      #   (  At 15:45 01.09.2013 there is  #
      # c[x] 0 cup(s) of coffee left       #
      # Coffee seems stale! Filled: Fri Aug 30 08:42:01 CEST 2013 #
      #      (-2 grams)                    #
      #                                    #
      ######################################
      
      1. Filled! =)

        ######################################
        # #
        # ) Coffee telnet v.5 #
        # ( At 11:31 04.09.2013 there is #
        # c[4] 4.6 cup(s) of coffee left #
        # (1099.98 grams) #
        # #
        ######################################

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