# Adafruit Sensirion SHT40, SHT41 & SHT45 Temperature & Humidity Sensors
## Overview
Sensirion Temperature/Humidity sensors are some of the finest & highest-accuracy devices you can get. And finally, we have some that have a true I2C interface for easy reading. The SHT40, SHT41, and SHT45 sensors are the fourth generation (started at the SHT10 and worked its way up to the top!).
The **SHT40** has an excellent ±1.8% typical relative humidity accuracy from 25 to 75% and ±0.2 °C typical accuracy from 0 to 75 °C.
The **SHT41** has an excellent ±1.8% typical relative humidity accuracy from 25 to 75% and ±0.2 °C typical accuracy from 0 to 75 °C.
The **SHT45** has an even more excellent ±1% typical relative humidity accuracy from 25 to 75% and ±0.1 °C typical accuracy from 0 to 75 °C.
Note that compared to the SHT40, the SHT41 has the same typical accuracy of ±1.8% RH from 25-75% but has much better accuracy over the full humidity range, with a typical accuracy of ±2% over the 0-100% RH range, whereas the SHT40 has a worst-case typical accuracy of ±3%. Also, the SHT41 max accuracy is ±3% where as the SHT40 has a max accuracy of ±6%. So basically, you'll get better accuracy for not-much-more cost. If you need the 'best' of the SHT4x series, you want the SHT45.
Other than these differences in relative humidity and temperature accuracy, **there is no discernible difference between these three chips.** The I2C addresses and code are identical for all. So, how do you know which one you have? **The text on the board indicates which breakout you have.**
## SHT45 with PTFE
- **PTFE Filter cover for protection:**
The filter membrane option for SHT4x family members inherently provides an additional barrier for all pollutants to enter the sensor opening, thus lowering negative influences on the sensing element. Mostly designed to keep particles and dust from accumulating and reducing the response time, the membrane also enables more efficient and easy cleaning, as it helps to reduce liquid intrusion into the sensor opening. Even though not selectively filtering, in general, physical barriers allow to reduce the amount of unwanted chemical contamination and help to remove potentially harmful components by facilitating wiping (flat sensor surface).
The integrated SHT4x PTFE membrane provides additional protection from particles and enables sensor operation in harsh conditions (according to IP67). The membrane has a thickness of 100 µm offering a filtration efficiency of \>99.99% for particles of 200 nm size and larger. Owing to the high permeability and the small volume between sensing element and membrane, the specified response time of the RH sensor is unaltered.
Primary:
Unlike some earlier SHT sensors, these sensors have a _true_ I2C interface for easy interfacing with only two wires (plus power and ground!). Thanks to the voltage regulator and level shifting circuitry we've included on the breakouts, they are also 3V or 5V compliant, so you can power and communicate with them using any microcontroller or microcomputer.
Such lovely chips - so we spun up breakout boards with the SHT4x and some supporting circuitry such as pullup resistors and capacitors. To make things even easier, we've included [SparkFun Qwiic](https://www.sparkfun.com/qwiic) compatible [STEMMA QT](https://learn.adafruit.com/introducing-adafruit-stemma-qt) connectors for the I2C bus so you don't even need to solder! [QT Cable is not included, but we have a variety in the shop](https://www.adafruit.com/?q=stemma+qt+cable&sort=BestMatch).
If you prefer working on a breadboard, each order comes with one fully assembled and tested PCB breakout and a small piece of header. You'll need to solder the header onto the PCB, but it's fairly easy and takes only a few minutes even for a beginner.
We've written both Arduino and CircuitPython/Python library code for these chips, so you can use it with just about any microcontroller or single-board computer like Raspberry Pi.
# Adafruit Sensirion SHT40, SHT41 & SHT45 Temperature & Humidity Sensors
## Pinouts
**The SHT40, SHT41, and SHT45 have identical pinouts.**
## Power Pins
- **VIN** - This is the power pin. To power the board, give it the same power as the logic level of your microcontroller - e.g. for a 5V microcontroller like Arduino, use 5V.
- **3V ** - This is the 3.3V output from the voltage regulator, you can grab up to 100mA from this if you like.
- **GND** - common ground for power and logic.
## I2C Logic Pins
The default I2C address is **0x44**.
- **SCL** - I2C clock pin, connect to your microcontroller I2C clock line. This pin is level shifted so you can use 3-5V logic, and there's a **10K pullup** on this pin.
- **SDA** - I2C data pin, connect to your microcontroller I2C data line. This pin is level shifted so you can use 3-5V logic, and there's a **10K pullup** on this pin.
- [**STEMMA QT**](https://learn.adafruit.com/introducing-adafruit-stemma-qt) ** -** These connectors allow you to connectors to dev boards with **STEMMA QT** connectors or to other things with [various associated accessories](https://www.adafruit.com/?q=JST%20SH%204).
The I2C address is 0x44 and **cannot be changed (a manufacturer limitation)**. If you must monitor multiple sensors with one microcontroller, look at the [PCA9546 4-channel](https://www.adafruit.com/product/5664) or [TCA9548A 8-channel multiplexer](https://www.adafruit.com/product/2717).
# Adafruit Sensirion SHT40, SHT41 & SHT45 Temperature & Humidity Sensors
## Arduino
The Arduino wiring and code for the SHT40, SHT41 and the SHT45 are identical!
Primary:
## Wiring
Connecting the SHT40 to your Feather or Arduino is easy:
- If you are running a Feather (3.3V), connect **Feather** **3V** to **board** **VIN**
- If you are running a 5V Arduino (Uno, etc.), connect **Arduino** **5V** to **board** **VIN**
- Connect **Feather or Arduino** **GND** to **board** **GND**
- Connect **Feather or Arduino** **SCL** to **board SCL**
- Connect **Feather or Arduino** **SDA** to **board SDA**
The final results should resemble the illustration above, showing an Adafruit Metro development board.
# Installation
You can install the **Adafruit SHT4X Library** for Arduino using the Library Manager in the Arduino IDE:
Click the **Manage Libraries ...** menu item, search for **Adafruit SHT4X** , and select the **Adafruit SHT4X** library:
Then follow the same process for the **Adafruit BusIO** library.
# Load Example
Open up **File -\> Examples -\> Adafruit SHT4X** **-\> SHT4test** and upload to your Arduino wired up to the sensor.
Upload the sketch to your board and open up the Serial Monitor ( **Tools-\>Serial Monitor** ). You should see the the values for temperature and humidity.
# Example Code
The following example code is part of the standard library, but illustrates how you can retrieve sensor data from the SHT40 for the temperature and humidity values:
https://github.com/adafruit/Adafruit_SHT4X/blob/master/examples/SHT4test/SHT4test.ino
# Adafruit Sensirion SHT40, SHT41 & SHT45 Temperature & Humidity Sensors
## Arduino Docs
# Adafruit Sensirion SHT40, SHT41 & SHT45 Temperature & Humidity Sensors
## Python & CircuitPython
It's easy to use the Adafruit Sensirion SHT40, SHT41, and SHT45 Temperature & Humidity Sensors with CircuitPython and the [Adafruit CircuitPython SHT4x](https://github.com/adafruit/Adafruit_CircuitPython_SHT4x) module. This module allows you to easily write Python code that reads temperature and humidity data from either sensor.
You can use these sensors with any CircuitPython microcontroller board or with a computer that has GPIO and Python [thanks to Adafruit\_Blinka, our CircuitPython-for-Python compatibility library](https://learn.adafruit.com/circuitpython-on-raspberrypi-linux).
**The wiring and code for the SHT40 works exactly the same way with the SHT41 and SHT45.**
Primary:
## CircuitPython Microcontroller Wiring
First wire up an SHT40 to your board exactly as follows. Here is an example of the SHT40 wired to a Feather using I2C:
- **Board 3V** to **sensor VIN**
- **Board GND** to **sensor GND**
- **Board SCL** to **sensor SCL**
- **Board SDA** to **sensor SDA**
## Python Computer Wiring
Since there's _dozens_ of Linux computers/boards you can use we will show wiring for Raspberry Pi. For other platforms, [please visit the guide for CircuitPython on Linux to see whether your platform is supported](https://learn.adafruit.com/circuitpython-on-raspberrypi-linux).
Here's the Raspberry Pi wired with I2C:
- **Pi 3V3** to **sensor VIN**
- **Pi GND** to **sensor GND**
- **Pi SCL** to **sensor SCL**
- **Pi SDA** to **sensor SDA**
## CircuitPython Installation of SHT4x Library
You'll need to install the [Adafruit CircuitPython SHT4x](https://github.com/adafruit/Adafruit_CircuitPython_SHT4x) library on your CircuitPython board.
First make sure you are running the [latest version of Adafruit CircuitPython](https://learn.adafruit.com/welcome-to-circuitpython/installing-circuitpython) for your board.
Next you'll need to install the necessary libraries to use the hardware--carefully follow the steps to find and install these libraries from [Adafruit's CircuitPython library bundle](https://circuitpython.org/libraries). Our CircuitPython starter guide has [a great page on how to install libraries from the library bundle](https://learn.adafruit.com/welcome-to-circuitpython/circuitpython-libraries).
Copy the following file from the bundle to the **lib** folder on your **CIRCUITPY** drive:
- **adafruit\_sht4x.mpy**
Before continuing make sure your board's **lib** folder or root filesystem has the **adafruit\_sht4x.mpy** file copied over.
Next [connect to the board's serial REPL ](https://learn.adafruit.com/welcome-to-circuitpython/the-repl)so you are at the CircuitPython `>>>` prompt.
## Python Installation of SHT4x Library
You'll need to install the **Adafruit\_Blinka** library that provides the CircuitPython support in Python. This may also require enabling I2C on your platform and verifying you are running Python 3. [Since each platform is a little different, and Linux changes often, please visit the CircuitPython on Linux guide to get your computer ready](https://learn.adafruit.com/circuitpython-on-raspberrypi-linux)!
Once that's done, from your command line run the following command:
- `pip3 install adafruit-circuitpython-sht4x`
If your default Python is version 3 you may need to run 'pip' instead. Just make sure you aren't trying to use CircuitPython on Python 2.x, it isn't supported!
## CircuitPython & Python Usage
To demonstrate the usage of the sensor we'll initialize it and read from the sensor in the board's Python REPL.
Run the following code to import the necessary modules and initialize the I2C connection with the sensor:
```python
import board
import adafruit_sht4x
sht = adafruit_sht4x.SHT4x(board.I2C())
```
Now you're ready to read values from the sensor using these properties:
- **relative\_humidity** - The current relative humidity in % rH
- **temperature** - The current temperature in degrees celsius
```python
print(sht.temperature)
print(sht.relative_humidity)
```
That's all there is to reading temperature and humidity from the SHT40 sensor!
## Full Example Code
https://github.com/adafruit/Adafruit_CircuitPython_SHT4x/blob/main/examples/sht4x_simpletest.py
# Adafruit Sensirion SHT40, SHT41 & SHT45 Temperature & Humidity Sensors
## Python Docs
# Adafruit Sensirion SHT40, SHT41 & SHT45 Temperature & Humidity Sensors
## WipperSnapper
Primary:
## What is WipperSnapper
WipperSnapper is a firmware designed to turn any WiFi-capable board into an Internet-of-Things device without programming a single line of code. WipperSnapper connects to [Adafruit IO](https://io.adafruit.com/), a web platform designed ([by Adafruit!](https://www.adafruit.com/about)) to _display_, _respond_, and _interact_ with your project's data.
Simply load the WipperSnapper firmware onto your board, add credentials, and plug it into power. Your board will automatically register itself with your Adafruit IO account.
From there, you can add _components_ to your board such as buttons, switches, potentiometers, sensors, and more! Components are _dynamically _added to hardware, so you can immediately start interacting, logging, and streaming the data your projects produce without writing code.
If you've never used WipperSnapper, click below to read through the quick start guide before continuing.
[Quickstart: Adafruit IO WipperSnapper](https://learn.adafruit.com/quickstart-adafruit-io-wippersnapper)
## Wiring
First, wire up an SHT40 to your board exactly as follows. Here is an example of the SHT40 wired to an [Adafruit ESP32 Feather V2](https://www.adafruit.com/product/5400) using I2C [with a STEMMA QT cable (no soldering required)](https://www.adafruit.com/product/4210)
- **Board 3V** to **sensor VIN (red wire on STEMMA QT)**
- **Board GND** to **sensor GND (black wire on STEMMA QT)**
- **Board SCL** to **sensor SCL (yellow wire on STEMMA QT)**
- **Board SDA** to **sensor SDA (blue wire on STEMMA QT)**
## Usage
Connect your board to Adafruit IO Wippersnapper and **[navigate to the WipperSnapper board list](https://io.adafruit.com/wippersnapper).**
On this page, **select the WipperSnapper board you're using** to be brought to the board's interface page.
If you do not see your board listed here - you need [to connect your board to Adafruit IO](https://learn.adafruit.com/quickstart-adafruit-io-wippersnapper) first.
On the device page, quickly **check that you're running the latest version of the WipperSnapper firmware**.
The device tile on the left indicates the version number of the firmware running on the connected board.
- **If the firmware version is green with a checkmark -** continue with this guide.
- **If the firmware version is red with an "X" -** [update to the latest WipperSnapper firmware](https://learn.adafruit.com/quickstart-adafruit-io-wippersnapper) on your board before continuing.
Next, make sure the sensor is plugged into your board and click the ** I2C Scan ** button.
You should see the SHT40's default I2C address of `0x44` pop-up in the I2C scan list.
### I don't see the sensor's I2C address listed!
First, double-check the connection and/or wiring between the sensor and the board.
Then, reset the board and let it re-connect to Adafruit IO WipperSnapper.
With the sensor detected in an I2C scan, you're ready to add the sensor to your board.
**Click the New Component button or the + button** to bring up the component picker.
Adafruit IO supports a large amount of components. To quickly find your sensor, type `SHT4` into the search bar, then select the **SHT40** component.
On the component configuration page, the SHT40's sensor address should be listed along with the sensor's settings.
The **Send Every** option is specific to each sensor's measurements. This option will tell the Feather how often it should read from each of the SHT40's two sensors and send the data to Adafruit IO. Measurements can range from every 30 seconds to every 24 hours.
For this example, set the **Send Every ** interval for each sensor to every 30 seconds.
Your device interface should now show the sensor components you created. After the interval you configured elapses, WipperSnapper will automatically read values from the sensor(s) and send them to Adafruit IO.
To view the data that has been logged from the sensor, click on the graph next to the sensor name.
Here you can see the feed history and edit things about the feed such as the name, privacy, webhooks associated with the feed and more. If you want to learn more about how feeds work, [check out this page](https://learn.adafruit.com/all-the-internet-of-things-episode-four-adafruit-io/advanced-feeds).
The SHT40 has two sensors that each have their own feeds. In this picture, we're looking at the Humidity sensor, but if you click on the graph icon for the different sensors you'll see their feed history.
For IO Free accounts, feed data is stored for a maximum of 30 days and there's a maximum of 10 feeds. In this guide, you created two feeds (one for each of the SHT40's sensors). If you’d like to store data for more than 30 days, increase the number of feeds (components) you can use with WipperSnapper, or increase your data rate to send more sensor measurements to Adafruit IO - [upgrade your account to Adafruit IO Plus](https://io.adafruit.com/plus).
# Adafruit Sensirion SHT40, SHT41 & SHT45 Temperature & Humidity Sensors
## Downloads
## Files:
- [SHT4x Datasheet](https://cdn-learn.adafruit.com/assets/assets/000/117/503/original/Datasheet_SHT4x.pdf?1673387912)
- [SHT4x Fritzing object in the Adafruit Fritzing Library](https://github.com/adafruit/Fritzing-Library/blob/master/parts/Adafruit%20SHT4x.fzpz)
- [SHT4x EagleCAD PCB files on GitHub](https://github.com/adafruit/Adafruit-SHT40-PCB)
- [SHT40 3D models on GitHub](https://github.com/adafruit/Adafruit_CAD_Parts/tree/main/4885%20SHT40%20Sensor)
- [SHT45 3D models on GitHub](https://github.com/adafruit/Adafruit_CAD_Parts/tree/main/5665%20SHT45%20Sensor)
# Schematic and Fab Print for SHT40
# Schematic and Fab Print for SHT41
# Schematic and Fab Print for SHT45
## Primary Products
### Adafruit Sensirion SHT40 Temperature & Humidity Sensor
[Adafruit Sensirion SHT40 Temperature & Humidity Sensor](https://www.adafruit.com/product/4885)
Sensirion Temperature/Humidity sensors are some of the finest & highest-accuracy devices you can get. And finally, we have some that have a true I2C interface for easy reading. The **SHT40** sensor is the fourth generation (started at the SHT10 and worked its way up...
In Stock
[Buy Now](https://www.adafruit.com/product/4885)
[Related Guides to the Product](https://learn.adafruit.com/products/4885/guides)
### Adafruit Sensirion SHT45 Precision Temperature & Humidity Sensor
[Adafruit Sensirion SHT45 Precision Temperature & Humidity Sensor](https://www.adafruit.com/product/5665)
Sensirion Temperature/Humidity sensors are some of the finest & highest-accuracy devices you can get. And finally, we have some that have a true I2C interface for easy reading. The **SHT45** sensor is the fourth generation (started at the SHT10 and worked its way up...
In Stock
[Buy Now](https://www.adafruit.com/product/5665)
[Related Guides to the Product](https://learn.adafruit.com/products/5665/guides)
### Adafruit Sensirion SHT41 Temperature & Humidity Sensor
[Adafruit Sensirion SHT41 Temperature & Humidity Sensor](https://www.adafruit.com/product/5776)
Sensirion Temperature/Humidity sensors are some of the finest & highest-accuracy devices you can get. The **SHT41** sensor is the fourth generation of I2C temperature and humidity sensor from Sensirion. (They started at the SHT10 and worked its way up to the top!)....
Out of Stock
[Buy Now](https://www.adafruit.com/product/5776)
[Related Guides to the Product](https://learn.adafruit.com/products/5776/guides)
### Adafruit Sensirion SHT45 Precision Temp & Humidity with PTFE
[Adafruit Sensirion SHT45 Precision Temp & Humidity with PTFE](https://www.adafruit.com/product/6174)
Sensirion Temperature/Humidity sensors are some of the finest & highest-accuracy devices you can get. And finally, we have some that have a true I2C interface for easy reading. The **SHT45** sensor is the fourth generation (started at the SHT10 and worked its way up...
Out of Stock
[Buy Now](https://www.adafruit.com/product/6174)
[Related Guides to the Product](https://learn.adafruit.com/products/6174/guides)
## Featured Products
### STEMMA QT / Qwiic JST SH 4-Pin Cable - 50mm Long
[STEMMA QT / Qwiic JST SH 4-Pin Cable - 50mm Long](https://www.adafruit.com/product/4399)
This 4-wire cable is 50mm / 1.9" long and fitted with JST SH female 4-pin connectors on both ends. Compared with the chunkier JST PH these are 1mm pitch instead of 2mm, but still have a nice latching feel, while being easy to insert and remove.
Out of Stock
[Buy Now](https://www.adafruit.com/product/4399)
[Related Guides to the Product](https://learn.adafruit.com/products/4399/guides)
### STEMMA QT / Qwiic JST SH 4-pin Cable - 100mm Long
[STEMMA QT / Qwiic JST SH 4-pin Cable - 100mm Long](https://www.adafruit.com/product/4210)
This 4-wire cable is a little over 100mm / 4" long and fitted with JST-SH female 4-pin connectors on both ends. Compared with the chunkier JST-PH these are 1mm pitch instead of 2mm, but still have a nice latching feel, while being easy to insert and remove.
Out of Stock
[Buy Now](https://www.adafruit.com/product/4210)
[Related Guides to the Product](https://learn.adafruit.com/products/4210/guides)
### STEMMA QT / Qwiic JST SH 4-Pin Cable - 200mm Long
[STEMMA QT / Qwiic JST SH 4-Pin Cable - 200mm Long](https://www.adafruit.com/product/4401)
This 4-wire cable is a little over 200mm / 7.8" long and fitted with JST-SH female 4-pin connectors on both ends. Compared with the chunkier JST-PH these are 1mm pitch instead of 2mm, but still have a nice latching feel, while being easy to insert and remove.
In Stock
[Buy Now](https://www.adafruit.com/product/4401)
[Related Guides to the Product](https://learn.adafruit.com/products/4401/guides)
## Related Guides
- [No-Code, No-Solder Monitoring For Perfect Bread](https://learn.adafruit.com/no-code-no-solder-temperature-monitoring-with-wippersnapper-offline.md)
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