Weather Station with BMP280 sensor and Raspberry Pi Pico

We have seen several weather stations which can be built using Arduino, Raspberry Pi, ESP8266 and many other development boards. There are several other sensors which can be used to build a weather station. In this tutorial we will learn building a Weather Station with BMP280 Sensor and Raspberry Pi Pico. We will be using Micro Python code to run this weather station and display the data in a LCD display.

Things Required

To build this project you need below modules

• Raspberry Pi PICO x 1
• BMP280 Sensor Module x 1
• LCD 16×2 (I2C Supported) x 1
• Jumper Cables

BMP280 Sensor

This sensor manufactured by Bosch. It is the next generation upgrade to the popular BMP085/BMP180/BMP183 sensor. BMP280 is a Barometric Pressure and Altitude Sensor. It has the ability to communicate using I2C/SPI protocol. This is available in a module for easy interfacing. It is one of the cheapest and tiny atmospheric Sensor breakout available in the market.

This precision sensor can sense the pressure with ±1 hPa absolute accuracy and temperature with ±1.0°C accuracy. The pressure changes with altitude and the pressure measurements are very precise in this module. This sensor can be used to measure altitude. This can work as an altimeter with ±1 meter accuracy.

The size of this module is very small and compact. This sensor can measure barometric pressure and temperature. This BMP280 sensor module can be used for monitoring indoor/outdoor conditions, weather forecasting, home automation. This sensor can be used for personal health and wellness monitoring.

For altitude sensing, this sensor gives a low altitude noise of 0.25m with fast conversion time. I2C interface makes this sensor module easy to connect with other boards. Multiple sensors should be connected using SPI protocol as I2C might create address collisions.

Specifications and Features

Working

The BMP280 sensor measures the Temperature and atmospheric pressure. We can also calculate altitude using these data. Then the data is sent to Raspberry Pi PICO and from there it is displayed using LCD display.

Connection Diagram

The connection is quite simple and easy to connect over a breadboard.

Code Analysis

We will focus on the major part of the codes to understand how it works.

First we are going to call the required libraries with below line of code

# import the required libraries
from bmp280 import *
from machine import Pin, I2C
import utime
from time import sleep
from lcd_api import LcdApi
from pico_i2c_lcd import I2cLcd

Now we will initialize LCD and configure I2C connectivity.

i2c = I2C(0, sda = Pin(0), scl = Pin(1), freq = 400000)
lcd = I2cLcd(i2c, 0x27, 2, 16)

Below code will configure the BMp280 sensor module connectivity

sclPin = Pin(1) # serial clock pin
sdaPin = Pin(0) # serial data pin

We will also initialize I2C for BMP280 sensor module

i2c_object = I2C(0, scl = sclPin,sda = sdaPin, freq = 1000000)

Below piece of code will Measure the temperature and send it

def altitude_HYP(hPa , temperature):
temperature = temperature
local_pressure = hPa
sea_level_pressure = 1013.25 # hPa 
pressure_ratio = sea_level_pressure/local_pressure # sea level pressure = 1013.25 hPa
h = (((pressure_ratio**(1/5.257)) - 1) * temperature ) / 0.0065
return h

Similarly pressure will be measured and sent.

def altitude_IBF(pressure):
local_pressure = pressure # Unit : hPa
sea_level_pressure = 1013.25 # Unit : hPa
pressure_ratio = local_pressure / sea_level_pressure
altitude = 44330*(1-(pressure_ratio**(1/5.255)))
return altitude

Final Code

You can download the code from below link and unzip it in a folder. There will be 4 python files present in the zip. Open these files in Thonny IDE and connect you PICO board to upload these files.

BMP280.py is for bmp280 sensor modules, lcd_api.py is used for display the data in LCD. pico_i2c_lcd.py is used for connecting the LCD using I2C protocol with Raspberry Pi PICO. Main.py is contains the main code of this project. You need to upload all these 4 files in Raspberry Pi Pico. To upload the file you can visit the article below.

Raspberry Pi PICO with Thonny IDE

Building & Testing

Once we have connected the components and modules as per the diagram above, its time to test it. Make sure the code is already uploaded. After powering on the Raspberry Pi PICO it will execute the code and show the temperature, pressure and altitude on LCD display.

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Summary

In this tutorial we have learnt building a Weather Station with BMP280 Sensor and Raspberry Pi Pico board. We have interfaced a LCD and a BMP280 temperature and pressure sensor with a Pico board. It is based om RP2040 based microcontroller. We have used micro python code to run this project. Do try this project and don’t forget to share the article with others.