BME280 Room Environment Station

One small chip, four readings: temperature, humidity, air pressure and estimated altitude every 2 seconds, with the day's minimum and maximum temperature. Then test how fast it reacts and where it reads most honestly.

One of 7 projects in the ESP32 Plant Monitoring Learning Kit — the parts below are from that kit.

What you build and learn

• Reading a BME280 over I2C with a library
• What relative humidity and air pressure mean
• How altitude can be estimated from pressure
• Sensor settling time and self-heating

What this project uses

Every item is in the kit — nothing extra to buy.

◇

ESP32U

In the kit

DIY-018 BME280 BME280 Temperature Humidity Pressure Sensor Module, Digital Barometric Sensor with I2C/SPI Interface, 1.8V–3.… DIY-018

In the kit

breadboard Transparent 830 Points Solderless Breadboard Clear Prototype Circuit Board MB-102 High Quality DIY Electronic… DIY-295

In the kit

jumper wires Jumper Wire Assorted Pack 120 Pieces - Male-to-Male, Male-to-Female, Female-to-Female 10cm Ribbon Cables for… DIY-212

In the kit

Build this with

ESP32 Plant Monitoring Learning Kit

All 6 parts in one box, with this project and 6 more to build from them.

AED 65.00 See the kit Add kit to cart

Need only these parts? Order them loose · from AED 52.41 ▾

Used in this project tick what you still need

DIY-018 BME280 BME280 Temperature Humidity Pressure Sensor Module, Digital Barometric Sensor with I2C/SPI Interface, 1.8V–3.… DIY-018 · ×1

AED 11.64

In stock

breadboard Transparent 830 Points Solderless Breadboard Clear Prototype Circuit Board MB-102 High Quality DIY Electronic… DIY-295 · ×1

AED 15.75

In stock

jumper wires Jumper Wire Assorted Pack 120 Pieces - Male-to-Male, Male-to-Female, Female-to-Female 10cm Ribbon Cables for… DIY-212 · ×1

AED 25.02

In stock

Selected parts AED 52.41

Add 3 parts to cart

One of each part. Packs (resistor assortment, jumper wires) already hold more than a single build needs. ESP32U: included in the kit, ask us for it loose. Delivery is AED 20, free on orders AED 100+.

Connections

Unplug USB before you change any wire. Pin names are the labels printed on the board.

Step by step

1. In Arduino IDE install the ESP32 boards package (Boards Manager → esp32 by Espressif) and, from Library Manager, Adafruit BME280 and Adafruit Unified Sensor. Select the ESP32 Dev Module board and your USB port.
2. With USB unplugged, wire the BME280: VIN to 3V3, GND, SDA to GPIO21, SCL to GPIO22. Place it at the far end of the breadboard, away from the ESP32, which gets warm.
3. Upload the BME280 room environment station sketch. Open Tools → Serial Monitor at 115200 baud, with the line ending set to Newline.
4. Leave it for 5 minutes and note where temperature and humidity settle.
5. Breathe gently towards the sensor once. Note how high humidity goes and how many seconds it takes to come back.
6. Move the board near a window, a fan or a plant and compare. Keep it out of direct sun and away from water.
7. Compare the pressure with a local weather report for your city.

Sketch for this project

Written for the board in the kit. Copy it into the Arduino IDE; change the pin numbers if you wire it differently.

/*
  ESP32 Plant Monitoring Learning Kit
  Project 4: BME280 room environment station

  Wiring: BME280 VIN 3V3, GND, SDA GPIO21, SCL GPIO22.

  What you learn: one I2C chip gives temperature, humidity and pressure.
  Pressure changes with the weather and with altitude - 1013 hPa is sea
  level on an average day. Keep the module away from your fingers and the
  warm ESP32, and watch how long a reading takes to settle after you
  breathe on it.
*/

#include <Wire.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BME280.h>

Adafruit_BME280 bme;

const float SEA_LEVEL_HPA = 1013.25;
const unsigned long REPORT_MS = 2000;
unsigned long lastReport = 0;
float minTemp = 99, maxTemp = -99;

void setup() {
  Serial.begin(115200);
  Wire.begin(21, 22);
  if (!bme.begin(0x76, &Wire)) {
    Serial.println("BME280 not found at 0x76 - try 0x77 or check SDA/SCL");
    while (true) delay(1000);
  }
  Serial.println("t_s,temp_c,humidity_pct,pressure_hpa,altitude_m,min_temp,max_temp");
}

void loop() {
  if (millis() - lastReport < REPORT_MS) return;
  lastReport = millis();
  float temperature = bme.readTemperature();
  float humidity = bme.readHumidity();
  float pressure = bme.readPressure() / 100.0;
  float altitude = bme.readAltitude(SEA_LEVEL_HPA);
  if (temperature < minTemp) minTemp = temperature;
  if (temperature > maxTemp) maxTemp = temperature;
  Serial.print(millis() / 1000); Serial.print(",");
  Serial.print(temperature, 1); Serial.print(",");
  Serial.print(humidity, 1); Serial.print(",");
  Serial.print(pressure, 1); Serial.print(",");
  Serial.print(altitude, 0); Serial.print(",");
  Serial.print(minTemp, 1); Serial.print(",");
  Serial.println(maxTemp, 1);
}

• The sketch looks for the BME280 at address 0x76. If it says not found, change it to 0x77 in bme.begin().
• SEA_LEVEL_HPA (1013.25) is the reference for the altitude estimate. Put in today's sea-level pressure from a weather report for a better altitude.
• REPORT_MS (2000) prints every 2 seconds.

What you should see

• A header t_s,temp_c,humidity_pct,pressure_hpa,altitude_m,min_temp,max_temp, then a row every 2 s.
• Indoor values roughly 20–35 °C and 30–70 % humidity; pressure near 1000–1020 hPa close to sea level.
• A humidity jump of several percent when you breathe on it, settling back over tens of seconds.

If it doesn't work

Try next

• Log a whole day with the Serial Data Logger and chart pressure — you can see weather fronts pass.
• Compare readings inside and outside a closed box with a damp cloth.

More from this kit

All projects →