RFID Drink System Eliminates The Need For Change


[Avatar-X] snagged a drink vending machine online a few years back, and has been selling drinks to his neighbors ever since. People are always asking him for change, and just the other day he was thirsty and out of change himself.  He considered adding an override key so that he could snag free drinks whenever he pleased, but decided to go all out and built a cash card system instead.

He didn’t know how to interface with the machine’s logic board, so after poring over the service manual he consulted with a support rep from the company that manufactured it. Luckily, he was able to get enough information from them to start making some headway. With his friend’s assistance, he was able to figure out which pins on the Bill Validator Interface needed to be shorted in order to simulate the addition of funds.

Using an Arduino with an Ethernet shield, LCD display, and an RFID reader, he had his PopCARD system up and running in no time. Now all his neighbors have to do when they want a drink is swipe their card in front of the machine and hit a button to add funds from their account.

As you can see in the video below it works great, and we’re sure his neighbors are pleased with the improvements he has made.

61 thoughts on “RFID Drink System Eliminates The Need For Change

  1. If I swipe and walk away does it leave the add funds button active or do I have to push it in a certain amount of time?

    ex What if I change my mind and don’t want to get a soda after swipping?

    Can I add $25 in the machine and cancel the transaction by hitting the refund button to get $25 dispensed from the machine? If so I’d put $100 on my card so I could get $25 for free,since he provides $5 for every $20 spent.

    He needs a cancel transaction and add funds back on card option, otherwise he’ll lose money giving away $5 for every $20 put on the card.

  2. Don’t most bill validators simply ground an output pin in pulses, once for every $0.25 that is taken in?

    And, about the hole, you could try the hole saw in reverse for a cleaner cut, but I was also wondering why the switch was not placed *through* the cardstock so that the button’s flange covered the edge of the hole…

  3. @Parcanman: Got any par cans you’re not using? :) Anyway, it’s a neat idea, but there’s not much information available about the microcontroller that runs the board, and the company that makes it isn’t even around anymore. I’d probably have more luck building an MDB “credit card reader” that works with my cards.

    As for the cancelling, I thought about that and I’ve done this:
    1. You can’t add more than $3 to the machine, since the highest priced item is $3. You can see this in my video where it says “max amount reached”.

    2. I’ve also disabled the refund feature, to prevent people from ripping me off by converting the bonus credit I give them back into cash. I’ve placed a large sign instructing people to check if their selection is sold out before they insert their money. The change feature still works, so if you put in $2, you can’t get it back, but if you buy something for $1, you’ll get a dollar of change.

    Also, this system is for my neighbors so they don’t really want to rip me off.

    @Hitek146: Yes, I found that my machine expects 2 pulses for each $1. Pulsing once does nothing, and pulsing 4 times adds $2.

    There is a gap of about 4mm between the cardstock and the plastic plate that I mounted the switch on to. I could put it “through” but it would bend the paper. I’m still looking for an ideal solution for the problem.

  4. You could fill one of the product chutes with beer, then have it appear permanently sold out until certain people swipe their card, then it “magically” becomes reloaded. Just say that that selection is broken and only tell the truth to the select few who will have carded access to it.

  5. Mmmm well u r a very thoughtful person , and good neighbor … among creative and having made to engadget…
    But it bugs me to think that I need to carry an extra card to buy a soda.. if had a bill reader u wouldn’t be having change problems… lol.
    In other hand…. I seen dispenser with credit card readers n one would think that more convenient… as a consumer. But logically .. having an ATM station it $$$ for the. Reseller…. thou well, u are on a private spot….keep up the great work!!! Cheer for ur next project.

  6. Has any of you people who complain about a friggin _hole_ taken a look at any of av’s other projects on his website?

    If not, do so. They’re amazing. Especially the car PC and what he’d done to the flat.

    Perhaps then you’ll realize you’re not dealing with a complete noob.

    tl;dr = This project rocks. And I love others too.

  7. This is seriously nice! What would be even cooler is some way for people to top up without pestering you. Perhaps a publicly available web page :)

    Well done though. You’ve made me want to buy a vending machine!

  8. Great project.

    Just something that pops in my mind: You could run a Webserver on the machine so your neighbours can acces the machine with their smartphone. Log in and select the drink they want over the web-interface. :-D

    As a plus someone could easy pay a drink of somebody else.

    Could also work whith e-mail or text messages.

  9. This has already been done on the cheap by a company called digivend everyone complaining about an extra card needs to open there eyes coke and Pepsi have used this for years.. I have many of these on my machines and are used every day

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