Uncovering The Echo Dot’s Hidden USB Port

If you upgraded to Amazon’s latest Echo Dot, you might have been surprised to find that the diminutive voice assistant had shed its USB port. Earlier models of the Dot used a garden variety micro USB port for power, which hackers eventually figured out also provided a helpful way to snoop around inside the device’s firmware. The fact that the USB port was deleted on the latest Echo Dot in favor of a simple barrel connector for power was seen by some as a sign that Amazon was trying to keep curious owners out of their hardware.

But as [Brian Dorey] shows, all they did was put a bump in the road. While they removed the external USB connector, the traces for it are still on the board waiting to be accessed. Even better, it turns out the USB data lines are connected to the test points located on the bottom of the Dot. All you need is a simple breakout that will connect through the existing opening in the device’s case, and you’ve got your USB port back.

So what can you do with USB on the Echo Dot? Well, not much right now. [Brian] found that the Dot shows up as a Mediatek device under Linux using lsusb, and fastboot can see it and even confirms the presence of a locked bootloader. It’s going to take some work from the community to see how deep this particular rabbit hole goes.

Even if you’re not interested in restoring its USB port, [Brian] has uncovered a wealth of fascinating hardware information about the Echo Dot during his deep-dive. He’s mapped out many of the test points located throughout the device’s PCBs, and found a few interesting points that might be worth further investigation. For example, he found that driving one of the pins high would trigger the Dot to mute its microphones; which could be useful for anyone looking to cover Alexa’s ears.

[Brian] first cracked open the Echo Dot last month, after scoring one for cheap during Amazon’s Prime Day sale. It looks like he’s making fairly rapid progress on unraveling the mysteries of this popular gadget, and we’re very interested in seeing where this research takes us.

57 thoughts on “Uncovering The Echo Dot’s Hidden USB Port

  1. after throwing away the *th micro usb cable this month because it would not charge my phone anymore, i completely understand the switch to barrel jack. Man, i hate that connector even more than the old scart video connector.

    1. What’s so bad about throwing out the cable instead of the entire device?

      Barrel jacks have the spring component as part of the device side connector. This is the same reason USB type A and Mini-B ports can wear out in ways that require a device replacement/repair – the springs are on the device side of the interface.

      With Micro-B, the springs were moved to the far less expensive and far more easily replacable cable.

          1. Cost, obviously. It’s not something that is going to be plugged and unplugged very often (at least in its intended use) and USB-C is still relatively expensive to implement.

          2. Because USB-C is a CF when it comes to power. Just look at the boondoggle of a USB-C implementation on the PI4. Is it just normal 5v usb power? 20v USB PD power? does the device support 20v or is it going to fry when it’s circuitry that expects 5v encounters 20v?

      1. Having lost zero devices to bad USB-A/Mini-B devices to bad ports, but countless cables, I see the trade-off differently. They moved the delicate bits to the part most easily damaged.

        You’re significantly more likely to run a cable over with a chair than you are to ever wear out the springiness of your contacts.

      2. Incidentally, in my experience the most likely failure mode for a PCB-mounted barrel jack is for the whole connector to be broken off the board, not for the contact to wear out.

        1. Once had a handheld 2M radio, and a packet TNC, with identical barrel jacks, except that one was *negative* centre pin.
          Grabbed the first to hand (was in a hurry) and got a perfectly rectangular smoke ring from between the case halves of the handheld 😭

          Never had that failure mode with USB.

          1. And a single PNP transistor can be a very low cost, low power way of preventing inverted polarity.

            I consider it a bad design if they didn’t consider flipping the Vin and GND. Even my amateur circuit boards have considerations for that.

        2. True… But you can then just run jumpers on the PWB to a wireside barrel recepticle and be back in business without needing to actually repair the pwb and align an smt connector.

      3. its not only the springly thing, but also the horrible flimsy way the cable is attached to the male micro-usb connector in most cables. and of course the way young adults “unplug” their phones by jerking at the cable or bending the connector. Brr.

      4. My experience with kindle tablets, ps4 controllers and numerous other devices is that the Micro B jacks are way more fragile than their mini and standard sized brethren. The cables break first sure, but the jacks break too, a lot.

    2. FWIW, I used to have the same problems before I went looking for better quality cables. I bought a four-pack of 6.5′ Volutz micro-USB cables well over a year ago and I have had zero problems with them, where cheap cables would do well to last a couple of months. They sell lengths from 1′ to 10′.

    3. What do you do to your USB cables??
      During the 20 years I’ve used USB I’ve seen exactly one bad USB cable, and even that was dead on arrival, not worn out.
      Come to think about it, this is the first I’ve heard anyone mention of a USB cable wearing out.

  2. >Amazon was trying to keep curious owners out of their hardware.
    Sorry, i don’t know Amazons business model: Do you BUY these ears or do you RENT them? If you BUY them it is YOUR hardware and you should be allowed to do anything you want with it! Yes i know, laws not always work this way, but they really should.

  3. If you really want a “cover your ears” feature I would suggest doing something more direct than setting some pin high. Is that just a link to a GPIO on the Dot’s CPU? Then it’s software that causes it to mute the mics when it sees it’s high. The very next firmware update could change that behavior.

    Take it apart all the way. Find the microphones. Add mechanical switches in-line. Now that’s how you add a “cover your ears” feature.

    1. That won’t work because it’s likely that they’re also using “microphonics” effect of ceramic capacitors. Maybe other physical phenomenas too like miniscule oscillations in CPU’s voltage regulator – this can be sensed and decoded although voice quality is abysmal.

          1. Got to agree it seems pretty unlikely – i’ve built a few audio projects over the years, and generally found that microphonics only occur with med-high capacitance ceramic types (when tantalum caps are often a better fit).

            I did a teardown on a broken 2nd gen Echo dot a while back out of curiosity, and I don’t remember really see anything in the echo that would warranty high value caps to lead to this – It had an array of 6 surface mounted mics spaced equidistantly around its periphery (each of which has holes through the device) so doubt it needs much else for doing its direction sensing, etc along with voice detection.

    2. Wild speculation: the ‘cover ears’ test point is in the same signal path as the physical mute button. If so, it’s not going to be broken by a software update any time soon, tinfoil hats not withstanding

    3. It was covered in the previous teardown, but there’s a physical chip that cuts power to the microphones (or at least, the ADCs) when it gets the signal. So mute is a hardware function triggered by software.

    1. The useful thing, would be to add something like a Ras Pi, other powerful ARM boards are available, with an off-line voice-rec thing listening for a trigger word. Then once it hears one, it de-deafens your Telescreen^H^H^HAmazon. That way you’re fairly sure the fucker isn’t spying on you.

      But by far superior is just not buying one. It’s appalling they even sell at all. And for the majority of people, they do nothing useful. Still, pet rocks were a big seller for a while.

      It’s appalling too how little people consider their own privacy. I’m not planning on murdering anybody either. But one day I might need to in a hurry, and I might not have had time to go turn the FIVE EY^H^H^HAmazon box first. From what I know from TV, murders are often really disorganised sorts of things. The terrorism’s fine, but do make sure you’ve unplugged all those Chinese Wifi cameras first. Unless of course Beijing is sponsoring your terrorism, in which case you might want to leave them on to make sure you get paid.

    1. Not really, all the brains is on the far side. Once they’re obsolete, they’re completely obsolete. They have a quite nice mic setup on board but even listening for the “wake up” word, they need to be, and are, completely awake and transmitting. Possibly there’s a noise-gate, and that’s about it.

      1. I heard that Amazon was considering having the Echos record 5-30 seconds of audio in a loop, so that you could say “What’s the weather today, Alexa?” and then it would use the recorded audio, so that one didn’t have to start with the wake word. I also read that they were considering making the device’s speech processing more powerful, so that it could process a lot of the simpler commands itself instead of sending the audio to the cloud for processing, so things like asking it to turn lights on and off or the weather etc… didn’t require cloud processing.

  4. They are a godsend to severely disabled people.

    If you’ve had a stroke or paralyzing accident Alexa is a MASSIVE improvement to quality of life, at a price that can’t be beat.

    I’m currently healthy enough I would no more buy one than I’d buy a wheelchair or a iron lung, but they are truly excellent assistive technology.

    1. Very true – Got one for my gran for exactly this reason. She’s in her mid-90s and partially sighted, plus the obvious mobility/dexterity issues of old age; so its a pretty ideal solution.

      It replaces the need for an alarm clock, a radio and a few other things – she never has to touch it either so unlike those things we don’t need to periodically buy replacements either when they inevitably get dropped once too many times!

      Similarly, i bought both her and my grandpa kindles the best part of a decade ago when their eyesight began to get steadily worse. Put simply, it’s awkward to get large print books, often expensive, and the selection is often quite limited – it made far more sense to buy kindles and ebooks, as the selection is near limitless and you can bump up the text size as big as needed. Very straightforward, but a massive quality of life thing for someone in their position.

  5. Great work!!!

    It would be so amazing if we could open these up and run Mycroft on them <3

    I do have two echo dots right now but I'm not very happy with contributing to Amazon's big data machine.

  6. It is very likely that most of these discards were usable. I haven’t run across many discarded usb cables that couldn’t have their fault corrected inside of five minutes. People are lazy and would often rather spend unneeded money on parts that have simply suffered the effects of our handling or mishandling. Spend 5 minutes looking at the connector and if you cannot figure out how it is kept attached and how that mechanism can wear or be distorted ask someone who can. Stop throwing away cords that have no issue other than operator error or lack of understanding of the attachment mechanism.

  7. I’m more interested in hacks that uses Alexa, it’s almost impossible to make it use a homemade device unless you also provide a server or cloud-based connection. The Alexa part interprets all your commands in the clouds and will need to execute them from there.

    Recently Philips Hue bulbs got a new version with bluetooth and it can be controlled directly by Alexa through the Echo Dot. I wonder if you can spoof such a bluetooth device to make Alexa turn on and off your own devices.

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