Nest Temperature Sensor Teardown

Geschrieben von: Forest
Veröffentlicht: 24/05/18
  • Kommentare: 7

Nest Temperature Sensor Teardown

Veröffentlicht: 24/05/18

Teardown

Einleitung

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    • Nest Temperature Sensor is a complementary device for the Nest Thermostat E or 3rd gen. It is created to help customers measure the temperature exactly where needed and control the thermostat accordingly

    • photo credit: John Miller/CNET

    • Positioned as a premium device, this Sensor is made from quality soft-touch plastic and comes in a decent box

    • The Sensor uses a single CR2 battery (included)

    • Diameter: 50mm, height: 22mm

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    • The back of the Sensor has a simple screw, which gives us access to the battery

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    • Removing 4 Torx T7 screws - and here it is - the PCB!

    • The inner side of the battery holder has 2 contacts on it's sides

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    • On The front we can spot

    • Bluetooth antenna (on the board)

    • Battery connectors

    • Murata 2x2mm RF switch connector, that can be used for RF testing

    • U11, U13 - probably some chips behind the shield, which is (unfortunately) firmly soldered. My guess: one of them is ultra-low power microcontroller and the other one is taking care of power delivery to the board

    • J1 - place for debug connector (empty in production)

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    • On the other side

    • This clear place on the PCB is for the antenna on the other side

    • nRF52832 BLE chip (maintains the only wireless connection of this device)

    • This is a tiny temperature sensor (not sure which one exactly)

    • The metal connector is a smart way to reinforce this tiny PCB

    • The sensor is on the edge, but still inside plastic case, and has no thermal channel to the outside (no vents or compound) - this fact rises a huge concern about the speed of the measurements

    • No temperature + humidity combo here, as seen in the Thermostats... really, Nest?! I mean, for $40 I had higher expectations..

    • That's it. Thanks for reading! Post comments if you have any questions or suggestions

Tinte & Feder

Forest

Mitglied seit: 17/11/16

502 Reputation

7 Kommentare

Good teardown report.

However, I think the orange part in Step4 should be Murata 2x2mm RF switch connector, which can be used for RF testing.

Not U.FL antenna connector, which is mainly designed to connect antenna.

Vitexia Gan -

Nice catch :)

I’ve updated the description, thanks!

Forest -

Please take pictures of both sides of all the components，eg front case ,back case, that’s important!thank you!

baozitao@gmail.com -

Can confirm. I have a small bedroom and I close the door when I sleep to make it darker. The result is that it can be quite a bit cooler or warmer in my bedroom than the thermostat measures. So I bought a Nest sensor. Then I woke up chilly one morning and turned the heat from 65 to 67. It was close to 75 in the bedroom before the Nest sensor thought it had hit 67.

John Doe -

At least the battery isn’t (strongly) thermally coupled to the board, but it doesn’t help. I bought a SensorPush Temp/humidity device which has an exposed sensor. Does an admirable job running down to -30C, but there’s a huge thermal lag (which is STILL not as bad as the Nest sensor), which I attribute to the giant coin cells mounted to the back of the sensor board.

John Doe -

For anyone that might land on this page, based on the markings on the physical features of the IC (size, pins, markings), the sensor appears to be from the TMP112 sensor line manufactured by Texas Instruments.

Levi -

Thanks for the Breakdown & Levi for the info. I started investigating the API and working with the sensor (I have 2 in my house) and am a bit dissapointed. documenting findings so far here if it is of interest: https://ssprod.me/blog/2022/11/14/a-clos...

Jean-Michel Roy -