In this article we connect a SHT31 humidity sensor to a Raspberry Pi Pico running Circuitpython
The digital SHT3x humidity sensor series takes sensor technology to a new level. As the successor of the SHT2x series it sets the industry standard in humidity sensing.
The SHT3x humidity sensor series consists of a low-cost version with the SHT30 humidity sensor, a standard version with the SHT31 humidity sensor, and a high-end version with the SHT35 humidity sensor. Automotive grade versions are also available.
The SHT3x humidity sensor series combines multiple functions and various interfaces (I2C, analog voltage output) with a applications-friendly, very wide operating voltage range (2.15 to 5.5 V).
The SHT3x humidity sensor is available in both large and small volumes.
The SHT3x builds on a completely new and optimized CMOSens® chip, which allows for increased reliability and improved accuracy specifications.
The SHT3x offers a range of new features, such as enhanced signal processing, two distinctive and user-selectable I2C addresses, an alert mode with programmable humidity and temperature limits, and communication speeds of up to 1 MHz.
Output : I²C, Voltage Out
Supply voltage range : 2.15 to 5.5 V
Energy consumption : 4.8µW (at 2.4 V, low repeatability, 1 measurement / s)
RH operating range : 0 – 100% RH
T operating range : -40 to +125°C (-40 to +257°F)
RH response time : 8 sec (tau63%)
|Pico||Raspberry Pi Pico Development Board|
|SHT31D||SHT31-D digital temperature and humidity sensor module|
|Connecting cables||Aliexpress link|
Black for GND
Red for V+
Blue for SDA
Yellow for SCL
So color coded for ease of use, this layout shows a connection to the module
I used Thonny for development
The following is based on a library , I copied the adafruit_sht31d.mpy library for this device to the lib folder on my Raspberry Pi Pico – https://circuitpython.org/libraries
This is the basic example which comes with the library
import time import board import adafruit_sht31d import busio i2c = busio.I2C(scl=board.GP1, sda=board.GP0) # uses board.SCL and board.SDA sensor = adafruit_sht31d.SHT31D(i2c) loopcount = 0 while True: print("\nTemperature: %0.1f C" % sensor.temperature) print("Humidity: %0.1f %%" % sensor.relative_humidity) loopcount += 1 time.sleep(2) # every 10 passes turn on the heater for 1 second if loopcount == 10: loopcount = 0 sensor.heater = True print("Sensor Heater status =", sensor.heater) time.sleep(1) sensor.heater = False print("Sensor Heater status =", sensor.heater)
Here is what I saw in Thonny REPL window
Temperature: 19.0 C
Humidity: 53.2 %
Temperature: 18.9 C
Humidity: 53.4 %
Temperature: 23.3 C
Humidity: 56.0 %
Temperature: 23.7 C
Humidity: 58.8 %