echo

33 Articles

Echo And Reverb In A Pretty Little Box

November 22, 2019 by 4 Comments

These days, if there’s a chip worth using, there will be a cheap pre-built module on eBay to make using it even easier. It’s a great time saver, and projects that used to take a couple of weekends can now be completed in a rainy afternoon. [lonesoulsurfer] knows how it is, and took advantage of this very approach to build this tidy echo & reverb effects box.

The build starts with a PT2399 echo/delay line module sourced of eBay, a part that we’ve learned much about thanks to the hard work of others. A resistor is cut off the board, enabling echo as well as reverb functionality. It’s laced up in a box with a couple of pots and a switch to control the effect, and hooked up with 6.5mm audio jacks to enable it to be easily used with guitars, synths, or karaoke machines.

It’s a fun build, and one that could serve as as a useful component in a larger setup. Adding a 3PDT switch could make it more useful as a guitar pedal, or it could be integrated into a Eurorack module, too. We’d particularly love to see the results possible from stuffing five of the modules in a single box and routing them into each other in new and exciting ways. If you pull that off, drop us a line.

Uncovering The Echo Dot’s Hidden USB Port

August 15, 2019 by 62 Comments

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.

Taking A Peek Inside Amazon’s Latest Dot

July 29, 2019 by 37 Comments

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.

A Sneak Peek At Anechoic Chamber Testing

November 17, 2018 by 23 Comments

[Mathieu Stephan] has something new in the works, and while he isn’t ready to take the wraps off of it yet, he was kind enough to document his experience putting the mysterious new gadget through its paces inside an anechoic chamber. Considering the majority of us will never get inside of one of these rooms, much less have the opportunity to test our own hardware in one, he figured it was the least he could do.

If you’re not familiar with an anechoic chamber, don’t feel bad. It’s not exactly the sort of thing you’ll have at the local makerspace. Put simply it’s a room designed to not only to remove echos on the inside, but also be completely isolated from the outside. But we aren’t just talking about sound deadening, the principle can also be adapted to work for electromagnetic waves. So not only is in the inside of the anechoic chamber audibly silent, it can also be radio silent.

This is important if you want to test the performance of things like antennas, as it allows you to remove outside interference. As [Mathieu] explains, both the receiver and transmitter can be placed in the chamber and connected to a vector network analyzer (VNA). The device is able to quantify how much energy is being transferred between the two devices, but the results will only be accurate if that’s the only thing the VNA sees on its input port.

[Mathieu] can’t reveal images of the hardware or the results of the analysis because that would give too much away at this point, but he does provide the cleverly edited video after the break as well as some generic information on antenna analysis and the type of results one receives from this sort of testing. Our very own [Jenny List] has a bit more information on the subject if you’d like to continue to live vicariously through the accounts of others. For the rest of us, we’ll just have to settle for some chicken wire and a wooden crate.

Continue reading “A Sneak Peek At Anechoic Chamber Testing” →

The PT2399 Delay/Echo Chip Data Sheet You Never Had

July 7, 2018 by 13 Comments

If you are fortunate enough to have had the opportunity to play with an analogue-reel-to-reel tape recorder in a well-equipped studio, you probably looped the tape around to create an echo, or a delay in the audio. It was a desirable effect to have, but not a practical one for a guitar pedal or similar portable accessory. Silicon alternatives for creating delays have been in production since the 1960s, first the so-called bucket brigade delay lines that used a switched chain of on-chip capacitors, and more recently all-digital chips that process the delay by storing samples in RAM. One of the more popular of those is the Princeton Technology PT2399, but it comes with something of a snag for the experimenter in the form of a sparse data sheet. Thankfully the folks at [Electrosmash] have come to the rescue on that front with a thorough technical examination of the chip that should fill in any gaps in the official documentation.

After a brief examination of the range of chips of which the 2399 is a part, they dive right into the chip’s internals by rearranging the internal circuit diagram from the data sheet to the point at which it makes more sense. At which point the difference between the chip’s delay and echo functions becomes obvious, through the inclusion of a feedback path.

We then are taken through the pins, examining what lies behind the power supply and analog inputs and outputs. We are somewhere between a data sheet and an app note here, as some of this is information rarely present even in really good data sheets. Finally, we are taken through the chip’s performance, with real-world distortion and noise measurements. Armed with this page, the would-be PT2399 designer really can say they know what they are working with.

Surprisingly few PT2399s have appeared on these pages, however one did pop up in the Synthbike.

Cloning The Echo Show With A Fabric Wrapped Pi

February 13, 2018 by 10 Comments

After seeing an Echo Show in the flesh plastic, [anonteapot] was inspired to create his own take on Amazon’s latest on-ramp to their ecosystem. He had the Raspberry Pi and a touch screen, but not much else. He doesn’t even have a dedicated work area at home, much less something as exotic as a 3D printer to run off a custom case. For this decidedly low-tech build, all that was required tool-wise was a razor blade knife and a screwdriver.

The majority of the device, which he refers to as the PiShow, is made of hand-cut pieces of MDF. In fact, the whole build relied on his ability to neatly cut pieces of MDF with hand tools on his bedroom floor. We wouldn’t suggest such a setup as a general rule, but respect for pushing ahead without so much as a table to work on.

To connect the pieces of MDF, he used angle brackets from the hardware store. These were originally 90 degrees, but he bent them by hand to achieve the angles seen in the final device. He notes that there was no specific angles he was aiming for when putting the box together; he simply wanted something that looked cool and was large enough internally to hold his electronics.

Covering the PiShow is some jersey material that [anonteapot] bought at a local fabric store. It has a little stretch to it so he was able to pull it tight over the MDF frame and keep the wrinkles out. As a general rule we don’t see many projects here at Hackaday that are wrapped in fabric, but we’ve got to admit, it makes for a nice final look.

The trickiest part of the build ended up being the side panels. While the rest of the frame was relatively simple, the sides needed to precisely conform to some fairly complex geometry. Luckily the side panels aren’t actually holding any weight, so he decided to just cut them out of cardboard. There’s a bit of a gap at the top, but he’s going to try and rectify that with a visit from his glue gun soon.

Internally things are sort of just hanging around inside the case, but since this device is never going to move off of the nightstand, it probably doesn’t need to be terribly secure. In truth, getting all the hardware mounted up cleanly with the construction methods available to [anonteapot] would have been a bit tricky anyway.

This is the first time we’ve seen somebody take a swing at replicating the Echo Show, usually we just see people trying to cram the Echo Dot into something else. If the software side is more your thing, be sure to check out this excellent guide on Alexa Skills development by our very own [Al Williams].

The Amazon Echo As A Listening Device

August 3, 2017 by 31 Comments

It is an inevitability that following swiftly on the heels of the release of a new device there will be an announcement of its rooting, reverse engineering, or other revealing of its hackability. Now the device in question is the Amazon Echo, as MWR Labs announce their work in persuading an Echo to yield the live audio from the microphone and turn the voice assistant device into a covert listening device.

The work hinges on a previous discovery and reverse engineering (PDF) of Amazon’s debug connector on the base of the Echo, which exposes both an SD card interface and a serial terminal. Following that work, they were able to gain root access to the device, analyze the structure of the audio buffers and how the different Echo processes use them, and run Amazon’s own “shmbuf_tool” application to pipe raw audio data to a network stream. Astoundingly this could be done without compromising the normal operation of the device.

It should be stressed, that this is an exploit that requires physical access to the device and a bit of knowledge to perform. But it’s not inconceivable that it could be made into a near-automated process requiring only a device with a set of pogo pins to be mated with an Echo that has had its cover quickly removed.

That said, inevitably there will be enough unused Echos floating around before too long that their rootability will make them useful to people in our community. We look forward to what interesting projects people come up with using rooted Echos.

This isn’t the first time we’ve covered the use of an Echo as a listening device.

Via Hacker News.

Amazon Echo image: FASTILY [CC BY-SA 4.0].