10. BME280 Mini Weather Station

Read temperature, atmospheric pressure, and optional humidity from a common BME280 module, then estimate altitude from a configured sea-level pressure.

Level: Intermediate · Time: 45 minutes

Requirements and wiring

ESP32 and BME280 I²C module
Adafruit BME280, Adafruit Unified Sensor, and Adafruit BusIO

BME280	ESP32
VIN / GND	3V3 / GND when the module is 3.3 V-compatible
SDA	GPIO 21
SCL	GPIO 22

Complete sketch


#include <PxServ.h>
#include <Wire.h>
#include <Adafruit_BME280.h>
 
const char* WIFI_SSID = "your_wifi_ssid";
const char* WIFI_PASSWORD = "your_wifi_password";
const char* PXSERV_API_KEY = "your_pxserv_api_key";
const float SEA_LEVEL_HPA = 1013.25;
 
PxServ client(PXSERV_API_KEY);
Adafruit_BME280 bme;
 
void setup() {
  Serial.begin(115200);
  Wire.begin(21, 22);
  if (!bme.begin(0x76)) {
    Serial.println("BME280 not found; check address 0x76/0x77");
    while (true) delay(1000);
  }
  PxServ::connectWifi(WIFI_SSID, WIFI_PASSWORD);
}
 
void loop() {
  float temperature = bme.readTemperature();
  float pressure = bme.readPressure() / 100.0f;
  float altitude = bme.readAltitude(SEA_LEVEL_HPA);
 
  client.setData("weather/temperature", String(temperature, 1));
  client.setData("weather/pressure-hpa", String(pressure, 1));
  client.setData("weather/altitude-m", String(altitude, 1));
  delay(30000);
}

Test and accuracy

Try address 0x77 if initialization fails. Replace SEA_LEVEL_HPA with current local sea-level pressure for a more useful altitude estimate. BME280 is a common choice because it measures temperature, pressure, and humidity in a single module.

Reference: Adafruit BME280 product guide

Continue with Advanced: Greenhouse Automation.