How to Connect an Arduino Sensor to ROS 2 on a Raspberry Pi (BME280 Tutorial)

This tutorial shows you how to connect an Arduino with a BME280 environmental sensor to a Raspberry Pi running ROS 2 Humble. You'll learn how to send sensor data over serial and publish it to a ROS 2 topic in real time. Great for weather stations, robotics projects, greenhouses, or just getting hands-on with embedded systems + ROS.

What You'll Need

Arduino Uno, Nano, or similar
BME280 sensor (I2C module)
Raspberry Pi (any model with Ubuntu and ROS 2 Humble installed)
USB cable for Arduino
Jumper wires (female-female)

Wiring the BME280 to Arduino (I2C)


BME280     →     Arduino
VCC        →     5V (or 3.3V depending on your module)
GND        →     GND
SDA        →     A4
SCL        →     A5

Arduino Code

Upload this code to your Arduino. It reads sensor values and prints them as comma-separated values over Serial.


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

Adafruit_BME280 bme;

void setup() {
  Serial.begin(9600);
  while (!Serial);

  if (!bme.begin(0x76)) {
    Serial.println("BME280 not found!");
    while (1);
  }

  Serial.println("BME280 found.");
}

void loop() {
  float temp = bme.readTemperature();
  float hum = bme.readHumidity();
  float pres = bme.readPressure() / 100.0F;

  Serial.print(temp);
  Serial.print(",");
  Serial.print(hum);
  Serial.print(",");
  Serial.println(pres);

  delay(2000);
}

Raspberry Pi Setup (ROS 2 Humble)

Make sure ROS 2 Humble is installed on your Pi. If you followed a tutorial like this:

sudo apt update
sudo apt install ros-humble-ros-base
source /opt/ros/humble/setup.bash

Create a ROS 2 Python Package


mkdir -p ~/ros2_ws/src
cd ~/ros2_ws/src
ros2 pkg create --build-type ament_python bme280_reader

ROS 2 Python Node: bme280_serial_node.py

Create the following file in ~/ros2_ws/src/bme280_reader/bme280_reader/bme280_serial_node.py

import rclpy
from rclpy.node import Node
import serial
from std_msgs.msg import Float32MultiArray

class BME280SerialNode(Node):
    def __init__(self):
        super().__init__('bme280_serial_reader')
        self.publisher_ = self.create_publisher(Float32MultiArray, 'bme280_data', 10)

        try:
            self.ser = serial.Serial('/dev/ttyACM1', 9600, timeout=1)
            self.get_logger().info("Connected to /dev/ttyACM1")
        except Exception as e:
            self.get_logger().error(f"Serial error: {e}")
            exit(1)

        self.timer = self.create_timer(2.0, self.read_serial)

    def read_serial(self):
        try:
            line = self.ser.readline().decode('utf-8').strip()
            if line:
                self.get_logger().info(f"RAW: {line}")
                parts = line.split(',')
                if len(parts) == 3:
                    temp = float(parts[0])
                    hum = float(parts[1])
                    pres = float(parts[2])
                    msg = Float32MultiArray(data=[temp, hum, pres])
                    self.publisher_.publish(msg)
        except Exception as e:
            self.get_logger().warn(f"Failed to read: {e}")

def main(args=None):
    rclpy.init(args=args)
    node = BME280SerialNode()
    rclpy.spin(node)
    node.destroy_node()
    rclpy.shutdown()

📜 Update setup.py

In ~/ros2_ws/src/bme280_reader/setup.py, add:


entry_points={
    'console_scripts': [
        'bme280_serial_node = bme280_reader.bme280_serial_node:main',
    ],
},

Build & Run


cd ~/ros2_ws
colcon build
source install/setup.bash
ros2 run bme280_reader bme280_serial_node

View the Data

In another terminal:


source ~/ros2_ws/install/setup.bash
ros2 topic echo /bme280_data

Example output:


data: [24.1, 49.3, 981.2]
---

Why This Matters

This is a real-world integration of ROS 2 with microcontroller sensors — perfect for robotics, IoT, or learning ROS 2 with actual hardware. Whether you're building a greenhouse, smart lab, or mobile robot, this pattern applies.