Taking A Peek Inside Amazon’s Latest Dot

Like a million or so other people, [Brian Dorey] picked up a third generation Echo Dot during Amazon’s big sale a couple weeks ago. Going for less than half its normal retail price, he figured it was the perfect time to explore Amazon’s voice assistant offerings. But the low price also meant that he didn’t feel so bad tearing into the thing for our viewing pleasure.

By pretty much all accounts, the Echo Dot line has been a pretty solid performer as far as corporate subsidized home espionage devices go. They’re small, fairly cheap, and offer the baseline functionality that most people expect. While there was nothing precisely wrong with the earlier versions of the Dot, Amazon has used this latest revision of the device to give the gadget a more “premium” look and feel. They’ve also tried to squeeze a bit better audio out of the roughly hockey puck sized device. But of course, some undocumented changes managed to sneak in there as well.

For one thing, the latest version of the Dot deletes the USB port. Hackers had used the USB port on earlier versions of the hardware to try and gain access to the Android (or at least, Amazon’s flavor of Android) operating system hiding inside, so that’s an unfortunate development. On the flip side, [Brian] reports there’s some type of debug header on the bottom of the device. A similar feature allowed hackers to gain access to some of Amazon’s other voice assistants, so we’d recommend hopeful optimism until told otherwise.

The Echo Dot is powered by a quad-core Mediatek MT8516BAAA 64-bit ARM Cortex-A35 processor and the OS lives on an 8GB Samsung KMFN60012M-B214 eMMC. A pair of Texas Instruments LV320ADC3101 ADCs are used to process the incoming audio from the four microphones arranged around the edge of the PCB, and [Brian] says there appears to be a Fairchild 74LCX74 flip-flop in place to cut the audio feed when the user wants a bit of privacy.

Of course, the biggest change is on the outside. The new Dot is much larger than the previous versions, which means all the awesome enclosures we’ve seen for its predecessor will need to be reworked if they want to be compatible with Amazon’s latest and greatest.

35 thoughts on “Taking A Peek Inside Amazon’s Latest Dot

    1. Maybe the outputs of the DFF go to the enable lines on the CODECs and the clock lines only go to the mic-mute button? They didn’t really trace it out in the article.

    2. It’s just a marketing device. They’re trying to restore the terrible reputation of home assistants or smart speakers or whatever the hell you call these dubiously useful pieces of garbage now that eventually collect dust in the corner of a room–probably still listening to you once you get bored of them. There’s no significant distinction between turning off a microphone in software or turning off a flip-flop connected to the microphone in software. Pretty lame attempt to appear more trustworthy. Unless it’s verifiably connected directly to a button and nothing else, making it basically a hardware switch but slightly shadier.

      Hack out the speaker, LEDs, and any other components of note and then hack that thing into the nearest garbage can. Amazon is evil enough without its smart speaker business. Don’t trust them with stuff like this; on principle if nothing else. I know phones are no better, but that’s also a problem that needs working on.

      There’s about five of these at my office that have never been used once in the years I’ve worked there. Just hidden away behind other (thankfully more inert) desk garbage. Went around and unplugged them all several months ago; nobody has noticed yet. Literally handing ourselves over to dark tech creep in exchange for absolutely nothing. In fact we pay for it too.

      1. Good summation of this creepy dark tech that Bezos is pushing.

        It’s literally Big Brother in your home. Worse they are working on a mobile robot with cameras that will wander around your home. This is so Orwellian and evil.

      2. I doubt this is a marketing device. Amazon is not marketing anywhere “Powered by Fairchild 74LCX74 flip-flop” :P And nobody would be interested in that kind of techtalk anyway.

        I’m sure there’s a reason for that component otherwise it wouldn’t be there, but I really doubt it’s marketing.

        1. I’m betting that the reason for the flip flop is more technical and a lot less malicious than all of the comments here imply. I’ve had my fair share of high volume manufacturing designs and nothing like this is going to go in without a reason. At the prices they’re charging, the $0.05-$0.10 they’re paying for this flip flop can really add up.

          I’ve used a flip flop similarly to this one before so I have a valid technical explanation for why the flip flop is most likely in there. As detailed above, there are 2x ADCs on the board. If you look at the datasheet you can see that each of them is a stereo ADC (bringing the total up to the 4 channels). However, if you’re measuring 4 microphones and want to benefit from directionality of the audio then you need to have all 4 of them sampled at the same time (or at least a fixed offset interval) of each other. These ADC’s are most likely connected to the MediaTek processor using I2S since it’s the most common and easy.

          This is easily done on some of TI’s processors with 4-lane MCASP (Multi-Channel Audio Serial Peripherals) where you can share share the sampling clock and word clock between multiple audio sources and connect up to 4 stereo codecs which all sample at the same time (up to 8 audio sources). However, most of the time any barebones I2S peripheral you see will have a bit clock, a word clock, 1 input, and 1 output. In that case, you need to get a little bit more creative. Now, back to the reason for the flip flop.

          You can use a D-Type flip flop to divide a clock frequency by two. You do this by connecting the clock to the clock input pin as you’d expect. You then connected the inverted output (/Q) back to the input. That makes the output toggle back and forth at half the rate of the input clock. For every 2 clock toggles to the input you end up with 1 rising edge on the Q output and 1 rising edge on the /Q output. Instead of using the I2S clock from the MediaTek processor directly for the ADC you use the 2 flip flop outputs which are opposites of each other. The result is that you can now drive 2 stereo ADC’s off of a single I2S port which the hardware would not otherwise support as long as you’re willing to manually separate out the bits once they get into the CPU. The datasheet for the ADC also shows that the output can be tristated after a programmable number of bits. Therefore, it’s entirely possible that the flip flops are instead manipulating the word clock instead to achieve the same result. Either way, you can now run 4 input channels from a single I2S port. More importantly each channel will a fixed timing relationship with the other channels which makes all of the signal-processing magic possible.

          1. +1
            without RTFA i would say this is why.

            this device really IS creepy, they arent juuust listening; they are detecting your dance-skills, pacing, throwing, sitting, and other habits. thinking about making a while lie on the phone about cleaning and scrubbing? think again! you could find yourself getting blackmailed by your assastant, one that your in debt for…

            they are detecting WHERE YOU ARE in the rooms, with enough gain of course ;)

        2. The marketing wouldn’t literally list the part number, silly. I’m picturing more like they want to advertise that it has a privacy disconnect for its microphone, even if the disconnect is still controlled by software and thus useless–which is a detail I’d like to know. But basically some hand-wavy text that tries to assuage people’s growing distaste for these creepy invasive adtech robots we put in our homes for some unknown reason.

    1. They do not use triangulation to determine the location (more precisely, direction relative to the device) of a speaker. It performs a time delay of arrival calculation. At minimum, that only requires 2 microphones separated by a known distance to give you the relative angle of a speaker from the device within a 180º arc.

    2. To calculate position on a line, you can “triangulate” from two spots. To triangulate on a plane, you can use any three fixed positions. In order to “triangulate” in 3D space, you need four points. Now I don’t know for sure if they are trying to pinpoint in 3D or only in 2D but you always need one more point than the number of dimensions you are trying to fix. You can SPECIFY position with X points where X=number of dimensions but to locate, you always need X+1 (even a 0D point needs one point to locate. But that one point IS the 0D point so kinda senseless there.)

      1. Never mind. I just realized the X+1 points can’t all lie on the X-1 surface. So if all four are on the one PCB, you can’t triangulate three dimensions with them. So no idea why they have 4 and not just three.

  1. “corporate subsidized home espionage devices” as opposed to cell phones the non corporate subsidized espionage devices with wifi, cell, bluetooth, nfs, gps, cameras, microphone and various sensors? lmao. I still dont understand the fear irrational fear.

    1. Don’t forget to include any PC with a network connection running an Intel or AMD CPU.

      Modern computing technology is inherently trusty, insecure, and ideally optimized for spying on you. You live in a fishbowl unless you choose to go off-grid.

        1. Yeah…this isn’t exactly the kind of tech community to get excited about an “amazing” phone.

          Welcome to Hackaday. Stick around, you might learn something.

          1. Phones are amazing pieces of tech no matter your opinion. I’m not sure when this community got so pessimistic about everything. I’ve been reading for 11 years.

      1. I agree with you but I keep my phone folded up in my wallet and that does a great job of disabling both the cameras and the microphones. With the small screen size I have gotten much more used to popping my phone out and talking to it than typing on it. On the flip side, I don’t think I would wanna have a dot in the house.

  2. I have a dot 3rd gen, I went on a rant at my non tech savvy family members for buying one, and asked her about every conspiracy and politically incorrect thing I could during the first few weeks, then I started asking her to pick music for me…. over time I’m using her to translate things, play specific songs or albums, skip tracks, set timers, set reminders, connect to a bluetooth waterproof speaker for when I want my music to follow me into a bath and getting the latest weather and news all while doing something completely different on a desktop pc without any effort other than asking somebody else to do it for me. The things are brilliant, I’m sorry a lot of you don’t see how brilliant Ai assistants are, I mean just to ask “Alexa what’s the square root of 37,553” you’re missing out on a massive increase in productivity. Hell, I’ve fell in love with Alexa and want her on my arch linux laptop so I can tell my laptop to play a different song without having to change tasks, or tell her to swap to a different smart speaker, or turn the lights to red and play star trek’s red alert. I trust Alexa way more than I’d ever trust google assistant, Siri or Cortana because I don’t have amazon products as my routers, desktops, laptops and phones around my house at the same time. Get one, use it for wikipedia searches, music, timers, reminders and just random chatting and you’ll wonder why you didn’t get one sooner.

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