Raspberry Pi Pico and HTU31D Sensor circuitpython example

In this article we connect a HTU31D to a Raspberry Pi Pico running Circuitpython

Sensor Information

The HTU31 is one of the smallest and most accurate humidity sensors on the market. Our precision engineering and 20+ years of experience in humidity and temperature combination sensors, enables us to provide fast response time, precision measurement, low hysteresis and sustained performance even when exposed to extreme temperature (-40° to 125°C) and humidity environments (0%- 100%).

The HTU31 humidity sensor includes both digital (D) and analog (V) versions, and combines multiple functions and various interfaces (I2C, analog, voltage output) with an application-friendly operating voltage range (3.3-5.5V with 5V typical).

Specifications

Parts Required

 

Name	Link
Pico	Raspberry Pi Pico Development Board
HTU31D	HTU31D temperature and humidity sensor module
Connecting cables	Aliexpress product link Amazon.com link Ebay link

 

Schematic/Connection

I used a HTU31D sensor

Black for GND
Red for V+
Blue for SDA
Yellow for SCL

 

Code Example

I used Thonny for development

The following is based on a library , I copied the adafruit_htu31d.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

[codesyntax lang=”python”]

import time
import board
import adafruit_htu31d
import busio

# Create sensor object, communicating over the board's default I2C bus
i2c = busio.I2C(scl=board.GP1, sda=board.GP0) # uses board.SCL and board.SDA
htu = adafruit_htu31d.HTU31D(i2c)
print("Found HTU31D with serial number", hex(htu.serial_number))

htu.heater = True
print("Heater is on?", htu.heater)
htu.heater = False
print("Heater is on?", htu.heater)

while True:
    temperature, relative_humidity = htu.measurements
    print("Temperature: %0.1f C" % temperature)
    print("Humidity: %0.1f %%" % relative_humidity)
    print("")
    time.sleep(1)

[/codesyntax]

Output

Here is what I saw in Thonny REPL window

Found HTU31D with serial number 0xd62fc4e
Heater is on? True
Heater is on? False
Temperature: 27.1 C
Humidity: 48.5 %

Temperature: 27.0 C
Humidity: 48.7 %

Temperature: 26.9 C
Humidity: 49.0 %

Temperature: 26.8 C
Humidity: 49.2 %

Temperature: 26.7 C
Humidity: 49.4 %

Links

https://www.tti.com/content/dam/ttiinc/manufacturers/te-connectivity/PDF/HTU31_Sensors_Datasheet.pdf