BMP280 with ESP32 DevKit V1 — pressure, altitude and the BME280 mix-up

The BMP280 measures air pressure (±1 hPa) and temperature. It is the sensor behind most hobby altimeters and weather-trend displays, and the cheap purple board costs about ₹80.

That purple board is a 3.3 V-only part with no regulator, so on the ESP32 DevKit V1 it goes straight to 3V3 and the I2C pins D21/D22 — no level shifting. The sketch checks both addresses, uses the datasheet’s low-noise weather settings, and prints temperature, pressure in hPa and altitude every two seconds.

Wiring

Every connection
ESP32 DevKit V1	BMP280 breakout (GY-BMP280)	Wire	Notes
3V3	VCC	red	The purple GY-BMP280-3.3 board has no regulator — 3V3 only. VIN (5 V) would damage the chip.
GND	GND	black
D22	SCL	yellow
D21	SDA	blue
GND	SDO	black	SDO to GND fixes the address at 0x76 (to 3V3 → 0x77). Leave CSB unconnected for I2C.

3.3 V (boards with a regulator: 3.3–5 V) part, 3.3 V board. The common purple 6-pin GY-BMP280-3.3 board has no regulator and no level shifting: power it from 3.3 V only. On a 5 V Uno, use a board with a regulator or a level shifter on SDA/SCL.

Board quirks

GPIO21 (SDA) and GPIO22 (SCL) are the ESP32’s default Wire pins; the sketch names them in Wire.begin(21, 22) so you can move them to any other free pair if needed.
Many sellers ship BME280 chips on “BMP280” boards and the other way round. The sketch accepts chip ID 0x58 (BMP280) and 0x60 (BME280) and tells you which one you have.
Altitude is calculated from pressure against 1013.25 hPa. Weather moves the reading by tens of metres; put your city’s current sea-level pressure (QNH, from any aviation weather site) into SEA_LEVEL_HPA for a real altitude.
The BMP280 is on the same 3.3 V rail as the ESP32 module, so its temperature reads a degree or two high when the board sits next to it. Use a short cable.

Code

bmp280-esp32.inoArduino C++Open in Playground Flash

// BMP280 temperature + pressure on an ESP32 DevKit V1 (purple GY-BMP280 board, 3.3 V only).
// VCC → 3V3, GND → GND, SCL → D22, SDA → D21. SDO → GND selects 0x76; CSB left open (I2C).
#include <Wire.h>
#include <Adafruit_BMP280.h>

Adafruit_BMP280 bmp(&Wire);
constexpr float SEA_LEVEL_HPA = 1013.25;  // set to your local QNH for a true altitude

bool startSensor() {
  const uint8_t addrs[] = {0x76, 0x77};
  for (uint8_t a : addrs) {
    if (bmp.begin(a, BMP280_CHIPID)) {
      Serial.printf("BMP280 found at 0x%02X (chip ID 0x%02X)\n", a, bmp.sensorID());
      return true;
    }
    if (bmp.begin(a, 0x60)) {  // a BME280 answers with 0x60 — still readable here
      Serial.printf("Chip at 0x%02X is a BME280 (ID 0x60) — reading temp/pressure only\n", a);
      return true;
    }
  }
  return false;
}

void setup() {
  Serial.begin(115200);
  Wire.begin(21, 22);  // SDA = GPIO21, SCL = GPIO22 (the DevKit V1 defaults)
  if (!startSensor()) {
    Serial.println("No BMP280 at 0x76 or 0x77 — check SDA/SCL and 3V3");
    while (true) delay(1000);
  }
  // Weather-station settings from the datasheet: low noise, slow is fine.
  bmp.setSampling(Adafruit_BMP280::MODE_NORMAL, Adafruit_BMP280::SAMPLING_X2,
                  Adafruit_BMP280::SAMPLING_X16, Adafruit_BMP280::FILTER_X16,
                  Adafruit_BMP280::STANDBY_MS_500);
}

void loop() {
  float t = bmp.readTemperature();
  float p = bmp.readPressure() / 100.0f;  // Pa → hPa
  float alt = bmp.readAltitude(SEA_LEVEL_HPA);
  Serial.printf("Temp %.2f °C  Pressure %.1f hPa  Altitude %.0f m\n", t, p, alt);
  delay(2000);
}

// BMP280 temperature + pressure on an ESP32 DevKit V1 (purple GY-BMP280 board, 3.3 V only).
// VCC → 3V3, GND → GND, SCL → D22, SDA → D21. SDO → GND selects 0x76; CSB left open (I2C).
#include <Wire.h>
#include <Adafruit_BMP280.h>

Adafruit_BMP280 bmp(&Wire);
constexpr float SEA_LEVEL_HPA = 1013.25;  // set to your local QNH for a true altitude

bool startSensor() {
  const uint8_t addrs[] = {0x76, 0x77};
  for (uint8_t a : addrs) {
    if (bmp.begin(a, BMP280_CHIPID)) {
      Serial.printf("BMP280 found at 0x%02X (chip ID 0x%02X)\n", a, bmp.sensorID());
      return true;
    }
    if (bmp.begin(a, 0x60)) {  // a BME280 answers with 0x60 — still readable here
      Serial.printf("Chip at 0x%02X is a BME280 (ID 0x60) — reading temp/pressure only\n", a);
      return true;
    }
  }
  return false;
}

void setup() {
  Serial.begin(115200);
  Wire.begin(21, 22);  // SDA = GPIO21, SCL = GPIO22 (the DevKit V1 defaults)
  if (!startSensor()) {
    Serial.println("No BMP280 at 0x76 or 0x77 — check SDA/SCL and 3V3");
    while (true) delay(1000);
  }
  // Weather-station settings from the datasheet: low noise, slow is fine.
  bmp.setSampling(Adafruit_BMP280::MODE_NORMAL, Adafruit_BMP280::SAMPLING_X2,
                  Adafruit_BMP280::SAMPLING_X16, Adafruit_BMP280::FILTER_X16,
                  Adafruit_BMP280::STANDBY_MS_500);
}

void loop() {
  float t = bmp.readTemperature();
  float p = bmp.readPressure() / 100.0f;  // Pa → hPa
  float alt = bmp.readAltitude(SEA_LEVEL_HPA);
  Serial.printf("Temp %.2f °C  Pressure %.1f hPa  Altitude %.0f m\n", t, p, alt);
  delay(2000);
}

Library: Adafruit BMP280 Library (Adafruit (also install Adafruit Unified Sensor)) — compiled with Adafruit BMP280 Library 3.0.0.

Expected serial output

Serial Monitor · 115200Output

BMP280 found at 0x76 (chip ID 0x58)
Temp 29.14 °C  Pressure 1006.8 hPa  Altitude 54 m
Temp 29.15 °C  Pressure 1006.8 hPa  Altitude 54 m

BMP280 found at 0x76 (chip ID 0x58)
Temp 29.14 °C  Pressure 1006.8 hPa  Altitude 54 m
Temp 29.15 °C  Pressure 1006.8 hPa  Altitude 54 m

Common errors

“No BMP280 at 0x76 or 0x77”

SDA/SCL swapped, a loose breadboard row, or the board powered from VIN and now damaged. Run the I2C scanner — no address at all means wiring.

Pressure reads about 600 hPa or other nonsense

Usually a damaged chip from 5 V on a 3.3 V-only board, or SDO floating so the address flips. Tie SDO to GND and power from 3V3.

Altitude is off by 50–100 m

Expected: altitude from pressure needs today’s sea-level pressure. Set SEA_LEVEL_HPA to the local QNH.