Weather Station with Raspberry Pi PICO and DHT11

Weather Station with Raspberry Pi PICO and DHT11

Do you need a weather station to monitor the temperature and humidity in your home or office? Instead of buying one, you can now make your own Weather Station with Raspberry Pi PICO and DHT11 sensor. When the project is complete, place the DHT11 sensor outside the window to get the most accurate weather readings or you can use this project to monitor the interior temperature as well.

Materials Required

  • Raspberry Pi Pico
  • 16×2 LCD
  • DHT11 Temperature and Humidity Sensor
  • Jumper Wires
  • MicroUSB cable to power your Raspberry Pi Pico board

Working

In this tutorial, we used the Raspberry Pi Pico board to read the temperature, humidity data. The data is displayed on a 16×2 LCD screen. We are using I2C protocol to connect the display with Raspberry Pi Pico.

Raspberry Pi Pico is a microcontroller board, rather than a mini computer like the other Pi boards. That makes it ideal for creating small projects. Raspberry Pi Pico is capable of handling analog input from sensors something other Pi boards cannot handle without an additional board. The Pico board can be programmed with C/C++ or MicroPython. We have chosen MicroPython for this tutorial.

Weather Station with Raspberry Pi PICO and DHT11

Connection

Connect the DHT11 sensor to the breadboard  and connect GND to the GND rail, Vcc to Vcc and the OUT signal to GPIO15 (Pin 20). For LCD screen,  connect SDA to Pin 5 and SCL to Pin 4. To power the LCD screen, connect LCD VCC to pin 36 on Raspberry Pi PICO board and LCD GND to the GND rail.

Weather Station with Raspberry Pi PICO and DHT11

Code Analysis

Before we jump in to the code lets understand the main python commands used. We have added the LCD I2C library along with DHT11 library. First we will declare the headers.

from pico_i2c_lcd import I2cLcd
from machine import Pin, I2C
from time import sleep
from dht import DHT11

Now we have initialized the LCD I2C connectivity.

i2c_lcd = I2C(id=1,scl=Pin(3),sda=Pin(2),freq=100000)

Similarly we have to configure the DHT11

pin = Pin(15)
dht11 = DHT11(pin,None,dht11=True)

If the condition is true then the data will be collected from DHT11 and if the data is not available the it will print a message. If the data is available then it will display them in Thonny IDE console.

while True:
           T,H = dht11.read()
           if T is None:
           print("Unable to connect to sensor")
else:
     print("Temperature :" + str(T) + "°C "+ "Humidity:"+ str(H) +"%")

Below commands will print the temperature and humidity in LCD display.

lcd.move_to(0,0)
lcd.putstr("Temperature: " + str(T) + chr (0xDF) + "C")
lcd.move_to(0,1)
lcd.putstr("Humidity: "+ str(H) +"%")

Complete Code

You can download the python code from the download link below. Once you downloaded you can unzip the it and open the python file using Thonny IDE.

Uploading Code in Raspberry Pi Pico

This project requires pin connections to your Pico board. If you haven’t already, you’ll need to solder pins to your Raspberry Pi Pico. To upload the code and configuring the Raspberry Pi Pico for the first time we have made a nice tutorial. You can follow it step by step and upload the code the using Thonny IDE to Raspberry Pi PICO.

How to configure Raspberry Pi PICO with Thonny IDE

Building & Testing

In a few seconds you should see the temperature and humidity of your room on the LCD screen. Once your Pico weather station is working, you can add an LED or a buzzer if the temperature or humidity goes above (or falls below) a threshold that you set. Now you can power the Pico using power bank charger or USB power adapter.

Weather Station with Raspberry Pi PICO and DHT11

Once you run the code and the connection is correct then you will receive the below output in your Thonny IDE Console.

Weather Station with Raspberry Pi PICO and DHT11

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Summary

In this tutorial we have learnt how to interface a DHT11 temperature and humidity sensor with Raspberry Pi Pico. We are also using micro python code to make it work. Also we have interfaced a LCD to display the sensor readings. We hope this article will help you to understand the interfacing technique. Do try this tutorial by yourself and don’t forget to share the article.

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