Sniffing Vending Machine Buses

Sniffing the Multidrop Bus


We’ve talked about a variety of protocols and how to deal with them in the past. Today, [Dan] is working on sniffing vending machine Multidrop Bus. The Multidrop Bus (MDB) protocol is a standard used in vending machines to connect devices such as currency collectors to the host controller.

To connect to the bus, interface hardware is required. [Dan] worked out compliant hardware and connected it to an Arduino. With the device on the bus, [Dan] got to work on an Arduino sketch to parse the MDB data into a human-readable format. With that working, the bus can easily be sniffed over the Arduino’s serial console.

This is just the start of a more involved project. Since this protocol is used to communicate with a vending machine’s currency collector or card reader, being able to communicate it would allow him to implement his own payment methods. The plan is to augment the vending machine he operates at Vancouver Hack Space to accept Bitcoin. We’re looking forward to seeing that project unfold.

A Bitcoin vending machine


Accessibility is one of the biggest hurdles facing the Bitcoin revolution, so [Mathias] found a way to give BTCs some market penetration by converting an old condom vending machine. The machine was 30 years old and required some clean up. [Mathias] also worked in a plywood adapter that attaches to the mount on the back so it can install on a wider variety of surfaces. This is an electricity-free alternative to selling coins: the machine is purely mechanical and it vends custom-made vouchers rather than the coins themselves, which you then redeem on the Kondocoin website.

The transaction isn’t as instant or snazzy as the Bitcoin briefcase converter from Defcon this year, but it still provides the advantage of an up-to-date exchange rate, as the vouchers themselves are valued at amount of Euros spent rather than a set amount of coins. The exchange rate is consulted later, when you punch in your voucher key. [Mathias] wants to share the wealth, too, and offers up the server software on github along with a detailed explanation of the process.

Robot steals soda from the vending machine


It’s very hard to tell from this photo because of the super bright blue LEDs, but this soda machine is being robbed by a robot.

We don’t condone theft, but neither does the creator of the project. [Ioduremetallique] is really just problem solving; doing something because he can. And we’d bet this type of thing will end up landing him a high-paying job some day (we’re assuming he’s currently in school).

The project is shown off in the video after the break. The gist of it is that a compact robot arm is put into the drop area of a vending machine. After the flap is closed the wired remote control is used to raise up the telescoping arm, and grip the soda can with the grippers. It’s brilliant and devious all at the same time. The entire video is in French, but the YouTube captions translator actually worked quite well with this video. To turn it one, use the ‘CC’ icon on the bottom of the video. We had to select the French captions before it would allow us to chose English from the translated captions list. About four minutes in we get a great look at the hardware itself… a super hack!

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Rube-Goldberg provides liquid refreshment


The image to the left doesn’t make this look like much, but inside of the cardboard vending machine lives a clever Rube-Goldberg device. The video after the break gives a look at the inner workings to show how a quarter manages to dispense a full can of Coke. But that’s about all the detail we get on the project.

There are two sets of counterweights used in the design. Some marbles, and what look like giant pinballs. The coin chute, located on the left side of the venting machine, funnels the money into the waiting marble. When the marble rolls off it lands on a spoon. The weight rotates the spoon-filled disk and causes one of the waiting pinballs to drop from their rack. As that metal ball falls it operates a ratcheting system to dispense just one can. It looks like the capacity of the machine is limited to two refreshing cans of sugary liquid, but that could be scaled up if more room were made for cans and counterweights alike.

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Tweeting beer dispenser requires co-worker approval


Having been faced with an empty beer fridge one too many times the team at Metalworks came up with an approval system for dispensing malted beverages. The trick was to remove the physical controls on a can dispenser. The only way you can get a cold one is to ask the machine via its twitter account. If there’s beer inside, it waits for one of your approved co-workers to give the go-ahead.

There are two versions of the machine. The first is a hacked refrigerator with a dispenser hole cut in the door. This resides in their Sydney office, apparently doesn’t work all that well, and is only shown in the video after the break.

The image above is version 2.0 which is located at their Singapore branch. It’s a much smaller device, but works very well since it started as a commercially available can dispenser. You can see the Arduino Leonardo and breadboard which make up the driver circuits.

There aren’t a ton of details on this, but it’s not hard to find about a million examples of an Arduino using Twitter. Here’s one that takes Morse code as an input and posts the message as a Tweet.

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Bilbio-mat is an awesome yet simple used book vending machine

You’ll find this used book vending machine at The Monkey’s Paw in Toronto, Canada. For two Loonies you can buy a random book from the machine’s hopper. Silly? Absolutely. But as you can see from the video after the break, the act of buying a book this way is a lot of fun, and we always like to see the insides of a machine like this.

[Craig Small's] creation looks vintage, and the chugga-chugga and mechanical bell that accompany each sale go along well with that appearance. Of course the machine is new. A trio of hoppers behind the façade hold stacks of books at a forty-five degree angle. Each stack is raised one at a time by a winch and pulley. Once the top book on the stack is high enough to slide into the dispenser chute the winch stops and the bell rings. A simple solution to dispensing something that is not a standard size.

Because the Biblio-Mat is meant to clear out the discount books, slight damage caused by falling down the chute won’t even be noticed. And if you end up really loving the book you can digitize it by running it through one of these.

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Making people pay for their beer at parties

A common problem at parties and get-togethers – although we don’t remember this happening – is regulating the amount of alcohol people consume. [Mike] came up with an interesting solution to make sure people don’t drink more than their fill by building a vending machine out of a minifridge that allows you to keep track of how many cans someone has taken.

[Mike] added a magnetic card reader on the side of a minifridge that allows any card with a magnetic stripe – a library card, credit card, or school ID – to serve as a unique identifier for each party guest. This card reader is connected to a Raspberry Pi which handles all the registration and eventual payment processing via Venmo

The mechanical portion of the build is a series of ramps built inside the fridge. At the bottom of this series of ramps, a servo controlled by an Arduino dispenses one can at a time when commanded to by the Raspi. The vending machine has a capacity of only 24 cans, but [Mike] says that could be improved with some CAD designed ramps inside a more modern fridge.