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​Appliance Science: How the Amazon Dash button works

Push button, order stuff. The Amazon Dash Button makes ordering things as simple as pressing a button when you realize you are running low. Here's how it works.

Smart Home

Push a button, order potato chips. Push another, order diapers. Really, who wants to bother with all of that tedious web browsing, let alone all of that horrid driving to the store business? It's so much easier to just push a button and, hey, presto, the products show up on your doorstep.

That's the dream that Amazon is pushing with the Dash Button, a simple device that allows you to order products from the online retail behemoth at, literally, the push of a button. Stick one on your washing machine, and when you run low on detergent, you can order more by pressing a button. So how does the Dash achieve this consumer-grade miracle? It's all about the Internet, of course. Let's look at how the Amazon Dash works.

The Dash Button is a very simple device. Inside the case are two simple components: a AA battery and a small circuit board. On this circuit board are a button (triggered by pressing the button on the case) and several small integrated circuits. These ICs include the processor with the easy-to-remember name of the STM32F205RG6, a Wi-Fi chip (the Broadcom BCM943362WCD4), and a flash Read-Only Memory (ROM) chip that holds the code the Dash Button runs on, plus a few other bits of info.

In addition, there are a few other chips that support these, a tiny LED by the button and a microphone. Before you ask, the microphone isn't part of an evil plot to spy on you* in your home; it is used to help set the Dash up when you first get it.


The guts of the Amazon Dash Button.

Richard Baguley/CNET

This combination means that the Dash Button is a computer. Not a particularly fast or powerful one, but it has enough brains to connect to the Internet over your Wi-Fi network and send messages. It is perhaps somewhat sobering to consider that all of this space-age power is focused on making it easier to buy more potato chips.

Get Dash(ded)

Amazon currently offers Dash Buttons for about a hundred products, ranging from drinks to paper towels, from snacks to diapers. Most of the products on offer are low-cost things that you buy regularly, so you will click the button whenever you realize that you're running low. Each Amazon Dash Button comes with a product logo on it and costs $4.99. You also need to be an Amazon Prime member, which includes no-cost 2-day shipping. The first time you use the Dash Button to order something, Amazon will give you a credit for the same amount, so it is basically free once you buy one and use it.

When you receive your Dash Button, you have to set it up. That's where the microphone comes in, as the Dash needs to know how to connect to your Wi-Fi network. The Amazon app on iOS or Android sends this information to the Dash Button using ultrasonic audio signals. You can't hear these high-frequency noises, but your phone, the Dash Button (and possibly your dog) can. Pressing and holding the button puts the Dash Button into a special mode that turns on the microphone and allows the Amazon App to send it this information. It's a pretty neat solution to how to pass this information to the device, and hardware hacker Jay Greco has done an excellent job of analyzing how this interesting communication method works.

Once the phone and Dash Button are connected, your mobile device sends the details of your Wi-Fi to the Dash Button, and the Button sends its unique serial number to the app. The Dash Button then says thank you, turns off the microphone, stores the Wi-Fi details and goes back to sleep. The app then sends this unique serial number to Amazon, which stores it. Finally, you get to specify what the button will order.

Colin McDonald/CNET

Send me stuff

When you press the button on the front of the Dash Button, a number of things happen inside it. First, the button press wakes it from a deep sleep, which is how the Dash Button can run for months from the small AA battery. Next, the device blinks the LED white to let you know you have pressed the button, and connects to the Internet over your Wi-Fi connection. Then, the fun bit happens: It orders the product from Amazon by sending a simple message to Amazon, the same way that you fill out information on a website and press "send". All that this message contains is the unique serial number and a few bits of diagnostic information, such as the Wi-Fi signal strength and the battery life.

That might sound like a bit of an anticlimax, but that's the trick of the Dash Button: It's a very simple computer dedicated to performing this one task. This is the clever bit, though, because part of the information that this message contains is the unique serial number assigned to the Dash Button when it was manufactured. This identifies the individual Dash Button, which Amazon has associated with your Amazon account and the specific product that the button buys. So, when you press the button and Amazon receives the short message, they know that you have pressed the button and want to order more potato chips. If you have multiple Dash Buttons, each one has a different serial number that is associated with a different product.

Once the message has been sent, Amazon sends a response that acknowledges the request, and the Dash Button changes the color of the LED to green, then dozes off again after a few seconds to save battery power. Amazon claims that the AA battery included in each Dash Button should be good for at least a thousand button presses.

If the process doesn't work (for example, if it can't join the Wi-Fi network or can't send the message), the Dash Button LED blinks red, then gives up and goes back to sleep. As I said, it's a simple device that doesn't have much in the way of brains, because it doesn't need to be smart; Amazon does all of the hard work on their servers.

There are also a few failsafes: You get an alert from the Amazon app that allows you to cancel the order for up to a half hour after the button is pressed, and you can't order each product more than once every 24 hours. That's useful if your dog finds the button and starts chewing on it; you can't end up with an order of eight tons of Mac & Cheese.

The next Dash

The Dash Button isn't the only way that Amazon is looking to make life easier (and thus make you more dependent on them, of course). The latest innovation the company is offering is a new Dash device that can scan barcodes. To order something with this, just scan the barcode, hit the button and Amazon will search their product list, find it and ship it out to you. You can also order a product without the barcode by hitting the microphone button and speaking the name: Amazon's Alexa voice recognition system will try and recognize the name and add it to your shopping cart. This works with their new Amazon Fresh grocery service and is only available in southern California at the moment.

Amazon is also looking to integrate the technology behind the Dash Button directly into devices; their Dash Replenishment service allows a manufacturer to build it into their products, so a product like a hand sanitizer dispenser can automatically order more sanitizer when it runs low.

Amazon's smart devices (Echo, Tap and Echo Dot) are more sophisticated versions of the Dash Button. By using Amazon's Alexa speech recognition and processing service, you can order products from Amazon by talking to each. Need more Doritos? Just say "Hey Alexa, reorder Doritos," into your Amazon device and it will order more without you having to get off the couch. You can try this service using a Web browser.

Amazon is also offering a hackable Dash Button that allows you to control what the button does, tying it into Amazon's cloud computing services. This can be used to trigger events like turning smart lights on and off, opening a website on your smart TV or counting something. You don't need to use this special button to do many of these things, though -- enterprising hackers have already worked out how to use the Dash Button for their own purposes, using the way it wakes up and joins your Wi-Fi network to do things like track the bathroom habits of a toddler or order an Uber.

So what does all of this mean? The Amazon Dash is a part of Amazon's plan to being the Everything Store, the one place you go to buy everything you need. It's an interesting approach that certainly makes it easier to order things you buy frequently, and it's a neat piece of hardware design.

Although it isn't clear how much the Dash Button costs to build, it is likely that it is more than $5, so Amazon is experimenting here. Amazon isn't expecting every user to buy everything use Dash, but by making the buttons and the system behind them, the company's creating a new way to buy things. And that's the aim of their master plan: To take over the world, one bag of chips (or diapers) at a time.

*As far we know.

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