MicroPython: ESP32/ESP8266 BME280 Web Server (Weather Station)

This tutorial is a step-by-step guide that covers how to build a standalone ESP32 or ESP8266 NodeMCU Web Server that displays BME280 sensor readings using MicroPython firmware. We’ll create an ESP32/ESP8266 Web Server that is mobile responsive and it can be accessed with any device with a browser in your local network.

If you want to learn how a BME280 sensor works, read our MicroPython Guide: BME280 with ESP32 and ESP8266 (Temperature, Humidity, Pressure).

We have similar guides using Arduino IDE:

• ESP32: BME280 Environmental Sensor using Arduino IDE (Pressure, Humidity, Temperature)
• ESP8266 NodeMCU: BME280 Environmental Sensor using Arduino IDE (Pressure, Humidity, Temperature)

Prerequisites

To follow this tutorial you need MicroPython firmware installed in your ESP32 or ESP8266 boards. You also need an IDE to write and upload the code to your board. We suggest using Thonny IDE or uPyCraft IDE:

• Thonny IDE:
  • Installing and getting started with Thonny IDE
  • Flashing MicroPython Firmware with esptool.py
• uPyCraft IDE:
  • Getting Started with uPyCraft IDE
  • Install uPyCraft IDE (Windows, Mac OS X, Linux)
  • Flash/Upload MicroPython Firmware to ESP32 and ESP8266

Learn more about MicroPython: MicroPython Programming with ESP32 and ESP8266 eBook.

Introducing the BME280 Sensor Module

The BME280 sensor module reads barometric pressure, temperature and humidity. Because pressure changes with altitude, you can also estimate altitude. There are several versions of this sensor module, but we’re using the one shown in the figure below.

This sensor communicates using I2C communication protocol, so the wiring is very simple. You can use the default ESP32 or ESP8266 I2C pins as shown in the following table:

BME280	ESP32	ESP8266
Vin	3.3V	3.3V
GND	GND	GND
SCL	GPIO 22	GPIO 5 (D1)
SDA	GPIO 21	GPIO 4 (D2)

Parts Required

For this project you need to wire the BME280 sensor module to the ESP32 or ESP8266 I2C pins. Here’s a list of parts you need for this tutorial:

• BME280 sensor module
• ESP32 or ESP8266 (read ESP32 vs ESP8266)
• Breadboard
• Jumper wires

You can use the preceding links or go directly to MakerAdvisor.com/tools to find all the parts for your projects at the best price!

Schematic – ESP32

Follow the next schematic diagram if you’re using an ESP32 board:

Recommended reading: ESP32 Pinout Reference Guide

Schematic – ESP8266

Follow the next schematic diagram if you’re using an ESP8266 board:

Recommended reading: ESP8266 Pinout Reference Guide

BME280 MicroPython Library

The library to read from the BME280 sensor isn’t part of the standard MicroPython library by default. So, you need to upload the following library to your ESP32/ESP8266 board (save it with the name BME280.py).

from machine import I2C
import time

# BME280 default address.
BME280_I2CADDR = 0x76

# Operating Modes
BME280_OSAMPLE_1 = 1
BME280_OSAMPLE_2 = 2
BME280_OSAMPLE_4 = 3
BME280_OSAMPLE_8 = 4
BME280_OSAMPLE_16 = 5

# BME280 Registers

BME280_REGISTER_DIG_T1 = 0x88  # Trimming parameter registers
BME280_REGISTER_DIG_T2 = 0x8A
BME280_REGISTER_DIG_T3 = 0x8C

BME280_REGISTER_DIG_P1 = 0x8E
BME280_REGISTER_DIG_P2 = 0x90
BME280_REGISTER_DIG_P3 = 0x92
BME280_REGISTER_DIG_P4 = 0x94
BME280_REGISTER_DIG_P5 = 0x96
BME280_REGISTER_DIG_P6 = 0x98
BME280_REGISTER_DIG_P7 = 0x9A
BME280_REGISTER_DIG_P8 = 0x9C
BME280_REGISTER_DIG_P9 = 0x9E

BME280_REGISTER_DIG_H1 = 0xA1
BME280_REGISTER_DIG_H2 = 0xE1
BME280_REGISTER_DIG_H3 = 0xE3
BME280_REGISTER_DIG_H4 = 0xE4
BME280_REGISTER_DIG_H5 = 0xE5
BME280_REGISTER_DIG_H6 = 0xE6
BME280_REGISTER_DIG_H7 = 0xE7

BME280_REGISTER_CHIPID = 0xD0
BME280_REGISTER_VERSION = 0xD1
BME280_REGISTER_SOFTRESET = 0xE0

BME280_REGISTER_CONTROL_HUM = 0xF2
BME280_REGISTER_CONTROL = 0xF4
BME280_REGISTER_CONFIG = 0xF5
BME280_REGISTER_PRESSURE_DATA = 0xF7
BME280_REGISTER_TEMP_DATA = 0xFA
BME280_REGISTER_HUMIDITY_DATA = 0xFD


class Device:
  """Class for communicating with an I2C device.

  Allows reading and writing 8-bit, 16-bit, and byte array values to
  registers on the device."""

  def __init__(self, address, i2c):
    """Create an instance of the I2C device at the specified address using
    the specified I2C interface object."""
    self._address = address
    self._i2c = i2c

  def writeRaw8(self, value):
    """Write an 8-bit value on the bus (without register)."""
    value = value & 0xFF
    self._i2c.writeto(self._address, value)

  def write8(self, register, value):
    """Write an 8-bit value to the specified register."""
    b=bytearray(1)
    b[0]=value & 0xFF
    self._i2c.writeto_mem(self._address, register, b)

  def write16(self, register, value):
    """Write a 16-bit value to the specified register."""
    value = value & 0xFFFF
    b=bytearray(2)
    b[0]= value & 0xFF
    b[1]= (value>>8) & 0xFF
    self.i2c.writeto_mem(self._address, register, value)

  def readRaw8(self):
    """Read an 8-bit value on the bus (without register)."""
    return int.from_bytes(self._i2c.readfrom(self._address, 1),'little') & 0xFF

  def readU8(self, register):
    """Read an unsigned byte from the specified register."""
    return int.from_bytes(
        self._i2c.readfrom_mem(self._address, register, 1),'little') & 0xFF

  def readS8(self, register):
    """Read a signed byte from the specified register."""
    result = self.readU8(register)
    if result > 127:
      result -= 256
    return result

  def readU16(self, register, little_endian=True):
    """Read an unsigned 16-bit value from the specified register, with the
    specified endianness (default little endian, or least significant byte
    first)."""
    result = int.from_bytes(
        self._i2c.readfrom_mem(self._address, register, 2),'little') & 0xFFFF
    if not little_endian:
      result = ((result << 8) & 0xFF00) + (result >> 8)
    return result

  def readS16(self, register, little_endian=True):
    """Read a signed 16-bit value from the specified register, with the
    specified endianness (default little endian, or least significant byte
    first)."""
    result = self.readU16(register, little_endian)
    if result > 32767:
      result -= 65536
    return result

  def readU16LE(self, register):
    """Read an unsigned 16-bit value from the specified register, in little
    endian byte order."""
    return self.readU16(register, little_endian=True)

  def readU16BE(self, register):
    """Read an unsigned 16-bit value from the specified register, in big
    endian byte order."""
    return self.readU16(register, little_endian=False)

  def readS16LE(self, register):
    """Read a signed 16-bit value from the specified register, in little
    endian byte order."""
    return self.readS16(register, little_endian=True)

  def readS16BE(self, register):
    """Read a signed 16-bit value from the specified register, in big
    endian byte order."""
    return self.readS16(register, little_endian=False)


class BME280:
  def __init__(self, mode=BME280_OSAMPLE_1, address=BME280_I2CADDR, i2c=None,
               **kwargs):
    # Check that mode is valid.
    if mode not in [BME280_OSAMPLE_1, BME280_OSAMPLE_2, BME280_OSAMPLE_4,
                    BME280_OSAMPLE_8, BME280_OSAMPLE_16]:
        raise ValueError(
            'Unexpected mode value {0}. Set mode to one of '
            'BME280_ULTRALOWPOWER, BME280_STANDARD, BME280_HIGHRES, or '
            'BME280_ULTRAHIGHRES'.format(mode))
    self._mode = mode
    # Create I2C device.
    if i2c is None:
      raise ValueError('An I2C object is required.')
    self._device = Device(address, i2c)
    # Load calibration values.
    self._load_calibration()
    self._device.write8(BME280_REGISTER_CONTROL, 0x3F)
    self.t_fine = 0

  def _load_calibration(self):

    self.dig_T1 = self._device.readU16LE(BME280_REGISTER_DIG_T1)
    self.dig_T2 = self._device.readS16LE(BME280_REGISTER_DIG_T2)
    self.dig_T3 = self._device.readS16LE(BME280_REGISTER_DIG_T3)

    self.dig_P1 = self._device.readU16LE(BME280_REGISTER_DIG_P1)
    self.dig_P2 = self._device.readS16LE(BME280_REGISTER_DIG_P2)
    self.dig_P3 = self._device.readS16LE(BME280_REGISTER_DIG_P3)
    self.dig_P4 = self._device.readS16LE(BME280_REGISTER_DIG_P4)
    self.dig_P5 = self._device.readS16LE(BME280_REGISTER_DIG_P5)
    self.dig_P6 = self._device.readS16LE(BME280_REGISTER_DIG_P6)
    self.dig_P7 = self._device.readS16LE(BME280_REGISTER_DIG_P7)
    self.dig_P8 = self._device.readS16LE(BME280_REGISTER_DIG_P8)
    self.dig_P9 = self._device.readS16LE(BME280_REGISTER_DIG_P9)

    self.dig_H1 = self._device.readU8(BME280_REGISTER_DIG_H1)
    self.dig_H2 = self._device.readS16LE(BME280_REGISTER_DIG_H2)
    self.dig_H3 = self._device.readU8(BME280_REGISTER_DIG_H3)
    self.dig_H6 = self._device.readS8(BME280_REGISTER_DIG_H7)

    h4 = self._device.readS8(BME280_REGISTER_DIG_H4)
    h4 = (h4 << 24) >> 20
    self.dig_H4 = h4 | (self._device.readU8(BME280_REGISTER_DIG_H5) & 0x0F)

    h5 = self._device.readS8(BME280_REGISTER_DIG_H6)
    h5 = (h5 << 24) >> 20
    self.dig_H5 = h5 | (
        self._device.readU8(BME280_REGISTER_DIG_H5) >> 4 & 0x0F)

  def read_raw_temp(self):
    """Reads the raw (uncompensated) temperature from the sensor."""
    meas = self._mode
    self._device.write8(BME280_REGISTER_CONTROL_HUM, meas)
    meas = self._mode << 5 | self._mode << 2 | 1
    self._device.write8(BME280_REGISTER_CONTROL, meas)
    sleep_time = 1250 + 2300 * (1 << self._mode)

    sleep_time = sleep_time + 2300 * (1 << self._mode) + 575
    sleep_time = sleep_time + 2300 * (1 << self._mode) + 575
    time.sleep_us(sleep_time)  # Wait the required time
    msb = self._device.readU8(BME280_REGISTER_TEMP_DATA)
    lsb = self._device.readU8(BME280_REGISTER_TEMP_DATA + 1)
    xlsb = self._device.readU8(BME280_REGISTER_TEMP_DATA + 2)
    raw = ((msb << 16) | (lsb << 8) | xlsb) >> 4
    return raw

  def read_raw_pressure(self):
    """Reads the raw (uncompensated) pressure level from the sensor."""
    """Assumes that the temperature has already been read """
    """i.e. that enough delay has been provided"""
    msb = self._device.readU8(BME280_REGISTER_PRESSURE_DATA)
    lsb = self._device.readU8(BME280_REGISTER_PRESSURE_DATA + 1)
    xlsb = self._device.readU8(BME280_REGISTER_PRESSURE_DATA + 2)
    raw = ((msb << 16) | (lsb << 8) | xlsb) >> 4
    return raw

  def read_raw_humidity(self):
    """Assumes that the temperature has already been read """
    """i.e. that enough delay has been provided"""
    msb = self._device.readU8(BME280_REGISTER_HUMIDITY_DATA)
    lsb = self._device.readU8(BME280_REGISTER_HUMIDITY_DATA + 1)
    raw = (msb << 8) | lsb
    return raw

  def read_temperature(self):
    """Get the compensated temperature in 0.01 of a degree celsius."""
    adc = self.read_raw_temp()
    var1 = ((adc >> 3) - (self.dig_T1 << 1)) * (self.dig_T2 >> 11)
    var2 = ((
        (((adc >> 4) - self.dig_T1) * ((adc >> 4) - self.dig_T1)) >> 12) *
        self.dig_T3) >> 14
    self.t_fine = var1 + var2
    return (self.t_fine * 5 + 128) >> 8

  def read_pressure(self):
    """Gets the compensated pressure in Pascals."""
    adc = self.read_raw_pressure()
    var1 = self.t_fine - 128000
    var2 = var1 * var1 * self.dig_P6
    var2 = var2 + ((var1 * self.dig_P5) << 17)
    var2 = var2 + (self.dig_P4 << 35)
    var1 = (((var1 * var1 * self.dig_P3) >> 8) +
            ((var1 * self.dig_P2) >> 12))
    var1 = (((1 << 47) + var1) * self.dig_P1) >> 33
    if var1 == 0:
      return 0
    p = 1048576 - adc
    p = (((p << 31) - var2) * 3125) // var1
    var1 = (self.dig_P9 * (p >> 13) * (p >> 13)) >> 25
    var2 = (self.dig_P8 * p) >> 19
    return ((p + var1 + var2) >> 8) + (self.dig_P7 << 4)

  def read_humidity(self):
    adc = self.read_raw_humidity()
    # print 'Raw humidity = {0:d}'.format (adc)
    h = self.t_fine - 76800
    h = (((((adc << 14) - (self.dig_H4 << 20) - (self.dig_H5 * h)) +
         16384) >> 15) * (((((((h * self.dig_H6) >> 10) * (((h *
                          self.dig_H3) >> 11) + 32768)) >> 10) + 2097152) *
                          self.dig_H2 + 8192) >> 14))
    h = h - (((((h >> 15) * (h >> 15)) >> 7) * self.dig_H1) >> 4)
    h = 0 if h < 0 else h
    h = 419430400 if h > 419430400 else h
    return h >> 12

  @property
  def temperature(self):
    "Return the temperature in degrees."
    t = self.read_temperature()
    ti = t // 100
    td = t - ti * 100
    return "{}.{:02d}C".format(ti, td)

  @property
  def pressure(self):
    "Return the temperature in hPa."
    p = self.read_pressure() // 256
    pi = p // 100
    pd = p - pi * 100
    return "{}.{:02d}hPa".format(pi, pd)

  @property
  def humidity(self):
    "Return the humidity in percent."
    h = self.read_humidity()
    hi = h // 1024
    hd = h * 100 // 1024 - hi * 100
    return "{}.{:02d}%".format(hi, hd)

View raw code

Follow the next set of instructions for the IDE you’re using:

• A. Upload BME280 library with uPyCraft IDE
• B. Upload BME280 library with Thonny IDE

A. Upload BME280 library with uPyCraft IDE

This section shows how to upload a library using uPyCraft IDE. If you’re using Thonny IDE, read the next section.

1. Create a new file by pressing the New File button (1).

2. Copy the BME280 library code into that file. The BME280 library code can be found here.

3. After copying the code, save the file by pressing the Save button (2).

4. Call this new file “BME280.py” and press ok.

5. Click the Download and Run button.

The file should be saved on the device folder with the name “BME280.py” as highlighted in the following figure.

Now, you can use the library functionalities in your code by importing the library.

B. Upload BME280 library with Thonny IDE

If you’re using Thonny IDE, follow the next steps:

1. Copy the library code to a new file. The BME280 library code can be found here.

2. Go to File > Save as…

3. Select save to “MicroPython device“:

4. Name your file as bme680.py and press the OK button:

And that’s it. The library was uploaded to your board. To make sure that it was uploaded successfully, go to File > Save as… and select the MicroPython device. Your file should be listed there:

After uploading the library to your board, you can use the library functionalities in your code by importing the library.

Code Web Server – BME280 Temperature, Humidity, and Pressure

In this project, we’ll display sensor readings from the BME280 temperature, humidity and pressure sensor on a web server that you can access on your local network.

For this example, you need three files:

• BME280.py: this is the file that contains all the methods to use the BME280 sensor. That’s the file you’ve uploaded previously.
• boot.py: runs when the device starts and sets up several configuration options like your network credentials, importing libraries, setting the pins, etc.
• main.py: this is the main script where we’ll handle the web server. It executes immediately after the boot.py.

Note: It is a good practice to include the boot.py and main.py files. However, if you prefer, you can include all the code in the main.py file.

boot.py

Create a new file in your IDE called boot.py and copy the following code.

# Complete project details at https://RandomNerdTutorials.com

try:
  import usocket as socket
except:
  import socket
  
from time import sleep

from machine import Pin, I2C
import network

import esp
esp.osdebug(None)

import gc
gc.collect()

import BME280

# ESP32 - Pin assignment
i2c = I2C(scl=Pin(22), sda=Pin(21), freq=10000)
# ESP8266 - Pin assignment
#i2c = I2C(scl=Pin(5), sda=Pin(4), freq=10000)

ssid = 'REPLACE_WITH_YOUR_SSID'
password = 'REPLACE_WITH_YOUR_PASSWORD'

station = network.WLAN(network.STA_IF)

station.active(True)
station.connect(ssid, password)

while station.isconnected() == False:
  pass

print('Connection successful')
print(station.ifconfig())

View raw code

This file imports the necessary libraries, defines the I2C pins to connect to the sensor and connects to your network.

In the code, we’re using the ESP32 I2C pins:

i2c = I2C(scl=Pin(5), sda=Pin(4), freq=10000)

If you’re using the ESP8266, comment the previous line and uncomment the following:

i2c = I2C(scl=Pin(22), sda=Pin(21), freq=10000)

Then, insert your network credentials in the following variables:

ssid = 'REPLACE_WITH_YOUR_SSID'
password = 'REPLACE_WITH_YOUR_PASSWORD'

main.py

In the main.py file is where we’ll create the web server and handle the requests. Copy the following code to your main.py file.

# Complete project details at https://RandomNerdTutorials.com

def web_page():
  bme = BME280.BME280(i2c=i2c)
  
  html = """<html><head><meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="icon" href="data:,"><style>body { text-align: center; font-family: "Trebuchet MS", Arial;}
  table { border-collapse: collapse; width:35%; margin-left:auto; margin-right:auto; }
  th { padding: 12px; background-color: #0043af; color: white; }
  tr { border: 1px solid #ddd; padding: 12px; }
  tr:hover { background-color: #bcbcbc; }
  td { border: none; padding: 12px; }
  .sensor { color:white; font-weight: bold; background-color: #bcbcbc; padding: 1px;
  </style></head><body><h1>ESP with BME280</h1>
  <table><tr><th>MEASUREMENT</th><th>VALUE</th></tr>
  <tr><td>Temp. Celsius</td><td><span class="sensor">""" + str(bme.temperature) + """</span></td></tr>
  <tr><td>Temp. Fahrenheit</td><td><span class="sensor">""" + str(round((bme.read_temperature()/100.0) * (9/5) + 32, 2))  + """F</span></td></tr>
  <tr><td>Pressure</td><td><span class="sensor">""" + str(bme.pressure) + """</span></td></tr>
  <tr><td>Humidity</td><td><span class="sensor">""" + str(bme.humidity) + """</span></td></tr></body></html>"""
  return html

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind(('', 80))
s.listen(5)

while True:
  try:
    if gc.mem_free() < 102000:
      gc.collect()
    conn, addr = s.accept()
    conn.settimeout(3.0)
    print('Got a connection from %s' % str(addr))
    request = conn.recv(1024)
    conn.settimeout(None)
    request = str(request)
    print('Content = %s' % request)
    response = web_page()
    conn.send('HTTP/1.1 200 OK\n')
    conn.send('Content-Type: text/html\n')
    conn.send('Connection: close\n\n')
    conn.sendall(response)
    conn.close()
  except OSError as e:
    conn.close()
    print('Connection closed')

View raw code

This code creates a socket server that sends an HTML page with the latest sensor readings when it receives a request on the ESP32 or ESP8266 IP address.

Basically, we have a function called web_page() that returns the HTML to build up the web page with the latest sensor readings. This HMTL text builds a table to display the readings:

html = """<html><head><meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="icon" href="data:,"><style>body { text-align: center; font-family: "Trebuchet MS", Arial;}
  table { border-collapse: collapse; width:35%; margin-left:auto; margin-right:auto; }
  th { padding: 12px; background-color: #0043af; color: white; }
  tr { border: 1px solid #ddd; padding: 12px; }
  tr:hover { background-color: #bcbcbc; }
  td { border: none; padding: 12px; }
  .sensor { color:white; font-weight: bold; background-color: #bcbcbc; padding: 1px;
  </style></head><body><h1>ESP with BME280</h1>
  <table><tr><th>MEASUREMENT</th><th>VALUE</th></tr>
  <tr><td>Temp. Celsius</td><td><span class="sensor">""" + str(bme.temperature) + """</span></td></tr>
  <tr><td>Temp. Fahrenheit</td><td><span class="sensor">""" + str(round((bme.read_temperature()/100.0) * (9/5) + 32, 2)) + """F</span></td></tr>
  <tr><td>Pressure</td><td><span class="sensor">""" + str(bme.pressure) + """</span></td></tr>
  <tr><td>Humidity</td><td><span class="sensor">""" + str(bme.humidity) + """</span></td></tr> 
  </body></html>"""

Then, we create a socket server that sends the HTML when it gets a request. The HTML text is then saved on the response variable:

response = web_page()

And sent to the client:

conn.sendall(response)

We’ve explained in great detail how these kind of web servers work in previous tutorials. So, if you want to learn how it works, you can read the following articles:

• MicroPython: ESP32/ESP8266 with DHT11/DHT22 Web Server
• ESP32/ESP8266 MicroPython Web Server – Control Outputs

Web Server Demonstration

Upload all the previous files to your ESP32 or ESP8266 board in the following order:

1. BME280.py
2. boot.py
3. main.py

If you don’t know how to upload code, you can read our getting started guides with uPyCraft IDE, or Thonny IDE:

• Getting Started with Thonny MicroPython (Python) IDE for ESP32 and ESP8266
• Getting Started with MicroPython on ESP32 and ESP8266 (uPyCraft IDE)

After uploading the code, your ESP32 or ESP8266 IP address should be displayed on the Serial Monitor.

Open a web browser in your local network and type your ESP IP address (in our example the IP is http://192.168.1.71). You should get a page with the latest sensor readings as shown in the following figure.

Auto refresh web page

With the web server script provided in this project, you need to refresh the web page to see the latest readings. If add the next meta tag inside the HTML <head></head> tags, your web page will auto refresh every 10 seconds:

<meta http-equiv="refresh" content="10">

Wrapping Up

We hope you’ve found this tutorial useful. We have other projects and tutorials with MicroPython that you may like:

• Low Power Weather Station Datalogger using ESP8266 and BME280 with MicroPython
• MicroPython: OLED Display with ESP32 and ESP8266
• MicroPython: ESP32/ESP8266 with DHT11/DHT22 Web Server
• MicroPython: WS2812B Addressable RGB LEDs with ESP32 and ESP8266

If you want to learn more about programming the ESP32 and ESP8266 boards with MicroPython, get access to our eBook: MicroPython Programming with ESP32 and ESP8266.

Thanks for reading.