Teardown: Nest Protect

A few notes on the inner workings of Nest's new smoke detector

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Merry Christmas everyone! We hope everyone has a great holiday season, whether you celebrate Christmas, Festivus, Hanukkah, or nothing at all.

You may remember back is 2011 when Nate busted open a Nest thermostat to have a look at its inside bits. We liked what we saw! So much so, in fact, that we installed a number of them around the building and eagerly awaited new gizmos from the folks at Nest. Well the wait has ended because we've just received our shiny new Nest Protect!

Nest Protect

The Nest Protect is a smoke and CO detector that connects to the internet and also talks to your Nest thermostat. We suspected that something like this might be coming when Nate stumbled upon a Zigbee radio while inside the thermostat and Nest did not disappoint. The Protect is packed with features (and supporting hardware) that make it more effective and less annoying than your average smoke detector. For instance, if the Protect senses a little bit of smoke it will give you a heads-up alert before it goes into full alarm mode. To deactivate the heads-up alert, simply wave your hand at the device and it will calm down. If you've ever had a touchy smoke detector installed near your kitchen, that feature alone probably justifies the $130 pricetag. Not only that, but because it talks to any Nest thermostats that you've installed, it can do crazy things like shut off your gas furnace if it detects a fire or CO danger.

Enough about features, though, I'm not trying to sell you a smoke alarm. This thing is absolutely packed with sensors and the design of the enclosure is really slick. I'm in the process of finishing up the full teardown right now, but as a teaser how about a few pictures of the internals and a list of interesting parts?

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I'll make sure you get more detail on this when the full-fledged teardown is complete, but here's a list of the most interesting parts:

Holy Cow! That's a lot of technology for $130... The layout of the devices is really clever, too. That big button on the front of the device? It doubles as a Fresnel lens for the PIR! That kind of design is present throughout the enclosure so be sure to stay tuned for the in-depth teardown where I'll inspect how all of these sensors work together!

Comments 21 comments

  • Comrad_Durandal / about 11 years ago / 3

    My problem with the Nest products (yes, all of them) is that the company signed an agreement with Intellectual Ventures. In my book, this makes them the scum of the earth - right up there with SCO, Oracle, and their ilk. This also makes them the anti-thesis of everything I see SparkFun being - closed, rigid, litigation-happy versus open, flexible, etc... Cool to tear their products down to see how they work and were built - just need to keep in mind that they sold their soul to the forces of evil along the way.

    Perhaps with a detailed tear-down, someone will make an open-source, anti-evil version of the Nest Protect.

    • Member #40169 / about 11 years ago / 1

      A broader view of the story would include that Honeywell sued Nest very early on for infringing Honeywell's patents, that the press release issued September 13th by Nest mentions that the sale to Intellectual Ventures is non-exclusive, gains Nest access to patents it may need to use, and access to a defensive patent portfolio. I disagree with the inherent assumption than any and all use of patents (licensing, cross-licensing, and defensive, for example) is "evil" and anti innovation.

  • scharkalvin / about 11 years ago / 3

    I managed to click on one of those snowflakes and it exploded into a lot more snow flakes.

    • Quazar / about 11 years ago / 4

      It is a snowflake invaders mini-game! H & L for left/right, and space to shoot

    • Member #240081 / about 11 years ago / 1

      Interesting observation. There is a (an accidental?) way to increase the difficulty level of sorts. You can only shoot 5 "bullets" at a time and when your ammo is replenished when a bullet reaches the top of the webpage. (NOT the top of the screen!) If you scroll DOWN the bullet takes longer to reach the top of the webpage, making the difficulty level higher...

  • Jeremy Sag / about 11 years ago / 2

    Snow Invaders!!! Winning!!! I got 108,900, then I had to get going, but I had fun goofing off for a bit! Merry Christmas guys!

  • HappyDuck / about 11 years ago / 2

    I was so ready to buy one of these, but then I discovered that the wired versions do not connect to the third wire (the red, or traveler wire) that is used to interconnect all the detectors in a home. Where I live, the building code requires all detectors to be interconnected, if one sounds, then every detector in the house must sound. True, all the Protects you buy will interconnect to each other, but depending on the layout, a 4 bedroom house might require 6 or 7 or more detectors. So the idea of buying one or two Protects to place in the house to enhance the Nest thermostat temp and auto-away features is not an option. Bummed.

  • jonsmirl / about 11 years ago / 2

    Light sensor is for the optical smoke detector?

    • That light sensor is probably use for there build in night light. They could also use that sensor to detect fire. For example, I remember reading something like this. There is different type of fires. For example, one of them can start in a couch and give out this thick smoke that is hard to be recognize by the standard smoke detector. To detect this type of fire, they can use a infrared/light sensor to see is the light beam is block by that specific smoke. Like a optocoupler. Imagine a IR LED at the end of a 1 inch straw. At the other end you have the receiver. It air tight. This becomes your "reference" measurement that is not affect by the smoke but only the light intensity. You then have other straw but with hole in the straw to let the smoke in. You use a other set of the same sensors. The smoke can now block the light beam and the system can compare that to the reference and trigger the alarm.

  • jonsmirl / about 11 years ago / 2

    Why do you need three CPUs? K60 has Ethernet and they never used it.

    What does a Figaro TGS-5342 cost? Nobody has them for sale.

    • I think that one CPU is dedicated to one single task: Detect fire! The other CPU are for other non safety related task like there voice speech, the motion detection, the wireless communications, etc.

    • Occam / about 11 years ago / 1

      I agree, that K60 is way more than powerful enough do everything. I've done more than what this gizmo needs to do with much less cpu power and resources. I just can imagine any functionality on this thing that requires a dedicated processor. I'll be interested in seeing how these components are "wired up" I hope the detailed treardown is revealing.

      I built a security device that continously monitored and decoded raw noisy output from a very simple OOK RF receiver, spoke, like this thing does using an ISD chip , monitored DC voltage, battery voltage, and and drove a very simple 300 baud modem chip including bespoke ring and line detection using just a PIC16C66 8K words OTP, 368B RAM running at 4 MHz.

      Maybe the second processor is an intelligent Watch Dog. This is a piece of safety equipment.

      • jonsmirl / about 11 years ago * / 1

        Third CPU is the EM357. It is a Cortex-M3 and capable of running user code too.

        • Occam / about 11 years ago / 1

          I'll almost give the designer the benefit of the doubt on the EM357, but I'm sure they could have used a dumb Zigbee module and the K60 would have been able to handle it.

  • Member #120279 / about 11 years ago / 1

    Hm, so it has temperature and humidity sensors - that's cool - but no way to get the data out AFAICT; it doesn't seem to be present on the (unofficial) API. Just having a wireless temp sensor per room would help to justify the cost for me.

  • dsffasdfdsafadsfasdfadsf / about 11 years ago / 1

    Why does it say warning on it? I have to know what that is four!

  • Member #295286 / about 11 years ago / 1

    I would like to comments that Nest Protect seem fit well with hearing world. But what about hearing impairment that need visual alert the world needs to depend on it. In only USA deaf and hard of hearing estimate about 40 million plus.

    • HappyDuck / about 11 years ago / 1

      I agree. Considering that Philips hue lights also have Zigbee radios it would be awesome if nest and Philips could figure out a way to have alarms flash all the hues in the house a specific color and with a specific pattern.

  • ClayBratt / about 11 years ago * / 1

    I was wrong :(

    • FlowerAskew / about 11 years ago / 2

      CO is not heavier than air. "The diffusion of carbon monoxide in air is relatively even, meaning that a source of carbon monoxide can distribute the gas evenly throughout the room and house." (Firstalert.com)

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