Introduction

The future of thermostats has a name, and that name is Nest. The 2nd Generation Nest Learning Thermostat is the thermostat that never stops learning. With hardware this smart, it's important for us to keep a watchful eye on it, so we naturally had to open it up!

Keep learning along with us as we tear into exciting new devices by following us on Twitter and liking our page on Facebook for the latest updates!

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    • Some impressive tech specs are nested in this learning thermostat, or learn-o-stat, as we lovingly call it:

    • 24 bit color LCD Screen with 320 x 320 pixel resolution

    • Built-in rechargeable lithium-ion battery

    • Various sensors (temperature, humidity, far-field activity, near-field activity, ambient light)

    • 802.11b/g/n and 802.15.4 Wi-Fi support (both at 2.4 Ghz)

    • Compatible with 95% of 24V heating and cooling systems, including gas, electric, forced air, heat pump, radiant, oil, hot water, solar, and geothermal

    Thermostat 2nd Generation called Nest is to me an excellent ideal object I personally believe would be a great object I would love to own. The learning Thermostat is simple to use so long as one follow step by step directions.

    vck_sm55 -

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    • As we open up the box, we find a Nest thermostat, an installation guide, a welcome guide, a concierge card, a screwdriver, screws, and trim kit.

    • The Nest is made up of two primary components: a wall-mounted base that connects to the signal lines from your HVAC system(s), and the snap-on display unit that houses the LCD and controls.

    • Nest advertises ease of installation for its thermostat. According to Nest, "three out of four customers install Nest in 30 minutes or less."

    • If you happen to be the one out of four experiencing difficulties during the install, don't despair. Simply purchase Nest Concierge Service.

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    • The base unit is home to ten spring-loaded connectors that let you easily route signal lines from all of your heating and cooling systems into the Nest:

    • Rc, Rh, W1, W2/AUX, Y1, Y2, G, O/B, Common “C”, Nest star

    • Responsible for both the wiring and the mounting of the Nest, this component is fitted with two oblong screw holes and a built-in bubble level to aid in a neat and tidy installation.

    • A few screws stand between us and the base motherboard—a quick turn of the screwdriver, and we see the green.

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    • With only light adhesive holding the base motherboard to its case, it doesn't take us long to pull it out for a closer look.

    • We rarely see circular circuit boards. It's quite refreshing and alliterates nicely.

    • The base motherboard is equipped with a surprising amount of hardware for an auxiliary board:

    • ST Microelectronics STM32L151VB ultra-low-power 32 MHz ARM Cortex-M3 MCU

    • Sensirion SHT20 humidity and temperature sensor

    • Texas Instruments LW051A 8-channel CMOS analog multiplexer/demultiplexer

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    • The back of the Nest display has two ports: a micro USB port that can be used for charging (and possibly hacking the Nest's software), and a proprietary 20-pin connector that fits onto the base unit's matching plug.

    • Removing a few screws allows us to separate the Nest display's rear panel from the rest of the unit and continue our exploration.

    • We'd like to point out that these screws can in fact be removed with the included driver. Way to make your product's internals accessible, Nest!

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    • Nothing makes us happier than a device with an easily replaceable battery. We feel the engineers at Nest Labs must have been thinking of us when they added these numbered flags showing three easy steps for battery removal.

    • We dutifully follow the steps to remove the battery:

    • Step 1: Disconnect the base connection ribbon cable.

    • Step 2: Pull the battery.

    • Step 3: Unplug the battery connector.

    • Step 3.5: Profit???

    Do not lift the battery connector. It is made to slide off of three pins that are extremely fragile. When you are looking at the battery, and can see and read the numbers 2 and 3 and the micro USB port is at the top, gently pull to the right or east. The wires of the connector will be exiting the plug straight down or south.

    Robert L Blasi -

    I believe I have a Gen 3 T-stat, however it looks identical to the photos here. Anyway, the connector does absolutely pull UP, not out. If you look carefully, there are 2 nibs to prevent it from pulling out sideways. To clear the nibs, you MUST pull it UP.

    Lastly - THANK YOU for this write-up. I manhandled my Nest last night, and it popped off the base and hit the wood floor. It refused to boot after that. No screen at all, just a flashing yellow light at the top. I tried a lot of troubleshooting stuff, but finally concluded something HAD to have come loose from the impact. Following the directions here, I was able to disassemble it far enough to see the red battery wire had slipped slightly out of the connector… just enough to see copper between the wire insulation and the connector. I pushed it back in, and secured it with a tiny bit of hot-melt glue. Put it all back together, and plugged it into the wall. It booted right up, with the full display as normal.

    Ron Goers -

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    • The lithium-ion rechargeable battery in the Nest is rated at 3.7 volts, 2.1 Wh (568 mAh).

    • The Nest receives a constant source of power from your home's thermostat lines, a low-power connection that can't provide enough juice for big operations like Wi-Fi broadcasts and powering the LCD. Keeping this battery topped off means the Nest always has reserve power to spare.

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    • At the other end of the rear panel's 'Pull' tab, we have a push option.

    • This ribbon cable-mounted button turns the whole display assembly into the menu navigator, allowing users to scroll with the exterior ring and select with a press of the display.

    • The cable is very securely adhered to the rear panel, but can be safely peeled off with a little patience and a lot of spudger.

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    • The Nest features an auto-away function that can detect when you've left your home and automatically switch to an "away temperature" to avoid heating or cooling an empty house.

    • This small board houses the two motion sensors (long and short range) responsible for this feature. These sensors are capable of detecting movement within a 150° field of vision.

    • Through a rather clever design, the sensor board has no cable connecting it to the motherboard. Instead, it rests on four screw posts that make up its contacts.

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    • We took a break from our headlong rush into the Nest's innards to sneak a peek under the large EMI shield that was covering the back of the motherboard. Unfortunately, there wasn't much to be seen.

    • After expelling a few more screws, we disconnect the LCD ribbon cable to free the front panel from the device.

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    • Our first foray into the front panel involves peeling off the small plastic plate adhered below the screen. Mild adhesive holds it securely in place, but is easily dispatched with a little patient spudgering.

    • The plastic plate turns out to actually be a window for infrared light, and is fitted with an array of Fresnel lenses that are used to widen the motion sensors' field of view and increase their range.

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    • The LCD is sandwiched between the front glass and a plastic frame. Adhesive secures the glass to the frame and the LCD to the glass.

    • It may look like the folks at Nest cut a couple of corners on the LCD, but in fact it's a rather remarkable round display, with only the visible portion populated with pixels.

    Any photos on how the ring is held in place and still allowed to rotate? Another great teardown guys!

    Fred Ting -

    The black plastic base plate (attached to the white backing) that is shown being removed in step 5 is what the aluminum ring glides on. Screws on the back secure the back base plate with the front display assembly, sandwiching the aluminum ring in place.

    xtremewaianae -

  13. By virtue of being a curved piece of glass, the front panel is a lens, capable of magnifying and focusing all of your <a href="../../home/not_yet_available?url=/Manifesto" target="_blank">important documents</a>.
    • By virtue of being a curved piece of glass, the front panel is a lens, capable of magnifying and focusing all of your important documents.

    • From the looks of things, we'd venture to guess that this is a plano-convex lens, designed to wrangle the light of the LCD into a focal point.

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    • With everything else out of the ring, we're able to pull out the motherboard for its closeup.

    • A quick look at the last component hanging off the side of the motherboard reveals an Avago ADBM-A350 optical finger navigation module, responsible for detecting the position of the outer steel ring.

    • This component works similarly to an optical mouse's sensor, by snapping images of the inside of the ring and comparing sequential pictures to determine position as it spins.

    Any thoughts on why they didn't use an IMU. Is it because of accuracy?

    Nahid Alam -

    Well, an IMU is for gyroscopic measurement and acceleration and stuff. That means that it would have to be mounted to the thing that’s moving, which is the ring. That would unbalance the ring and make it hard for the IMU to rotate freely and still be attached to the board. IMU’s just aren’t used for rotational measurement.

    So that leaves a few kinds of positional sensors, and I’ll focus on optical and magnetic. Most of the magnetic ones measure the position of a specific rotating axis, so they have an axle sticking out of them. This isn’t practical for the nest, because the ring would have to be mounted to this axle. The ring doesn’t go through the center of the device in the first place. It’s a ring.

    Optical sensors just make the most sense. They look at the inside of the ring as it scrolls. They don’t need an axle or any crazy hardware, just a good position to view the inside of the ring.

    Liam Powell -

    Does the optical sensor need a light to be able to see the inside of the ring?

    Jacob Das -

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    • With all of the I/O connections on the back, the main motherboard houses all of its important ICs on the front:

    • Texas Instruments AM3703CUS Sitara ARM Cortex A8 microprocessor

    • Texas Instruments TPS65921B power management and USB single chip

    • Samsung K4X51163PK 512 Mb mobile DRAM

    • Ember EM357 integrated ZigBee/802.15.4 system-on-chip

    • Micron MT29F2G16ABBEAH4 2 Gb NAND flash memory

    • Skyworks 2436L high power 2.4 GHz 802.15.4 front-end module

    • And under that last EMI shield: Texas Instruments WL1270B 802.11 b/g/n Wi-Fi solution, just like the one we found in the Kindle Fire

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    • Nest Learning Thermostat 2nd Generation Repairability Score: 9 out of 10 (10 is easiest to repair)

    • Battery is clearly intended to be user-replaceable (with built-in directions) and can be removed with the included Phillips screwdriver.

    • Solid construction surrounded by a hefty steel ring makes for great durability.

    • Separation of components onto two motherboards increases modularity.

    • Light adhesive holds the front panel assembly together, slightly increasing difficulty of replacing the LCD or glass.

    Where can I order a new outer screen mine is cracked?

    Ronald Gruenwald -

David Hodson

Member since: 14/04/10

151517 Reputation

21 comments

Have an estimate for the BOM cost to make this?

Ufixit -

You are pointing out that the ring movement is detected visually. Are there any photos of the inner side of the ring that moves past the detector? Does it have a special pattern on it to make motion detection easier, or is it just a plain metal surface?

JoeMuc2014 -

There are no mechanical parts used inside. The inside of the aluminum ring has what looks like an etched pattern, similar in fashion to a screen. An optic transceiver, like an optical mouse, is located to register the pattern as the ring is turned.

xtremewaianae -

Dose anyone know the supplier of this thermostat?

Hua Jason -

好像是中国大陆的昌硕科技。

ROEWE1226 -

Nest labs

Well duh

Logan -

Dose anyone know which process node used for Micron NAND flash and Samsung Mobile DRAM in the report above?

Jeffrey Huang -

Does anyone know how possible it would be to use the ring / button / display for a completely separate purpose? Basically want use this hardware for a completely new project if that sounds doable?

Kevin OConnor -

Does anybody where to buy these screws and threatened inserts which mounts PIR sensor?

vippercom -

And one more question, there is a connector on display board with two screws. Do you know where to buy it?

vippercom -

I've read a review about this one at https://www.geekwrapped.com/home/smart-w... bought, work great, and it feels so bad to see you tear it all up :D

damradovicc -

Hello!

Does anyone know which component is blue smd located on the back of the base

I suspect it's a fuse, is it possible? What value could it have?

oscar bravo -

Could be an inductor, they often come in shiny plastic cases and the coil is visible. The PCB closeup is not close enough to be sure though...

JoeMuc2014 -

does anyone know the manufacturer and part-number of the display?

Andreas -

Hello,

my Nest Gen2 W1 fuse is blown. Does anybody know the part number or at least the current rating of the fuse?

Thanks,

Jo

Wijoyo Utomo -

Why would you want to strip down the thermostat when its a KNOWN issue ?. They have sent us out a replacement, and less than 6 months later, that one took the same route too. Cheap components with a high price.

bob f -

Where can I buy nest 2nd gen thermostat front glass replacement?

C E -

My stainless steel ring has no pattern etched on it. My unit stooped recognizing that the ring was being turned, so I disassembled it to see if there was something I could do. Unfortunately, I lifted the battery cable instead of pulling it to the right and broke a pin. If any one needs some more pictures of something, let me know as I will keep this around for a little while.

Robert L Blasi -

On this 20-pin connector which pins are responsible to power the thermostat?

Rafał Foryś -

Please do a teardown of the 2020 Soli Sensor version. Thank you.

latoyamendez -

Where is the temperature sensor located? I’m surprised it works with no venting holes on this thing.

Tom Henry -