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Tutorials

I2C Environmental Sensor Module

Overview​

This tutorial walks through a compact I2C environmental sensor module built around a BME280 temperature, humidity, and pressure sensor. The board exposes power, ground, SDA, and SCL on a header so it can connect to a microcontroller, Raspberry Pi, or breadboard wiring harness.

Circuit Requirements​

The module needs:

  • a BME280 sensor connected to the I2C bus
  • pull-up resistors on SDA and SCL
  • decoupling near the sensor power pins
  • a 4-pin external connector for power and I2C
  • an optional OLED expansion header sharing the same I2C bus

Final Circuit Preview​

Step 1: Add the Sensor​

The BME280 is the main part on the module. In a production design you should match the footprint and pinout to the exact package and supplier part you plan to order.

Schematic Circuit Preview

Step 2: Add Pull-Up Resistors​

I2C is an open-drain bus, so SDA and SCL need pull-up resistors. 4.7k is a common starting value for short sensor-module wiring at standard I2C speeds.

Step 3: Add Headers​

J1 is the main host connector. J2 is optional and can be used for a small OLED display or another I2C device. Both headers share the same VCC, GND, SDA, and SCL nets.

Example Microcontroller Code​

import { Bme280 } from "your-bme280-driver"

const sensor = new Bme280({ bus: 1, address: 0x76 })
await sensor.init()

const reading = await sensor.read()
console.log({
  temperatureC: reading.temperature,
  humidityPercent: reading.humidity,
  pressurePa: reading.pressure,
})

Layout Guidance​

Place the decoupling capacitor close to the sensor power pins, keep SDA and SCL short when possible, and avoid placing hot components directly next to the sensor package because that can skew temperature readings.