BMP180 I2C Address: 0x77

How to set the address

There is no address pin: the address is set at the factory, so it is always 0x77.

Devices that use the same addresses

Two devices on the same bus can’t answer on the same address. These modules from our list also use 0x77:

Device	What it is	Shared address
BME280	temperature, humidity and pressure sensor	0x77
BME680	gas (VOC), temperature, humidity and pressure sensor	0x77
BME688	AI gas, temperature, humidity and pressure sensor	0x77
BMP280	pressure and temperature sensor	0x77
BMP388	pressure and temperature sensor	0x77
MS5611-01BA	barometric pressure sensor (altimeter)	0x77
PCA9685	16-channel 12-bit PWM / servo driver	0x77
TCA9548A	8-channel I2C multiplexer	0x77

If two of them end up on the same address, move one with its address pin, put one behind a TCA9548A multiplexer (0x70–0x77), or use a second I²C bus: the ESP32, ESP32-S3 and RP2040 have two I²C controllers (the ESP32-C3 has one).

Check your whole bus →Add the BMP180 and your other modules: the checker finds conflicts, suggests free addresses and sizes the pull-ups.

7-bit and 8-bit address

I²C addresses are 7 bits long. Some datasheets and libraries write them as 8-bit numbers, with the read/write bit added on the right: that is why the same chip can appear as 0x77 or 0xEE. Arduino’s Wire library and ESPHome use the 7-bit form.

7-bit	Binary	8-bit write	8-bit read
0x77	1110111	0xEE	0xEF

Check that it answers

Upload this sketch with the BMP180 wired to SDA and SCL: it tries every address the chip can use and prints the one that answers. On an ESP32 the default pins are GPIO21 (SDA) and GPIO22 (SCL); on an Arduino Uno, A4 and A5.

#include <Wire.h>

const byte ADDRS[] = {0x77};

void setup() {
  Serial.begin(115200);
  Wire.begin();
  for (byte a : ADDRS) {
    Wire.beginTransmission(a);
    if (Wire.endTransmission() == 0) {
      Serial.print("BMP180 answers at 0x");
      if (a < 0x10) Serial.print('0');
      Serial.println(a, HEX);
      return;
    }
  }
  Serial.println("No answer: check the wiring");
}

void loop() {}

In ESPHome the bus is scanned at boot (scan: true is the default): the log lists every address that answers.

i2c:
  sda: GPIO21
  scl: GPIO22
  scan: true

Pull-up resistors

SDA and SCL need pull-up resistors to the supply. Many breakout boards already carry them, often 4.7 kΩ or 10 kΩ, and with several boards on the bus they add up in parallel. The I²C checker works out the allowed range for your bus voltage and speed.

Frequently asked questions

What is the I2C address of the BMP180?

0x77. It is fixed: there is no address pin.

Can I use more than one BMP180 on the same bus?

Not directly: the address is fixed, so two would clash. Put each one on a different channel of a TCA9548A multiplexer, or use a second I²C bus.

Why doesn’t the BMP180 show up in an I2C scan?

Check, in this order: SDA and SCL not swapped; ground shared between the boards; pull-up resistors on SDA and SCL; the module powered at the voltage it is made for; and that your code uses the 7-bit address (0x77), not the 8-bit one (0xEE).

Addresses checked against the BMP180 datasheet.

BMP180 I²C address