Integrate BME280 Sensor in Zephyr Using Device Tree for Temp and Humidity

Integrating a BME280 Environmental Sensor in Zephyr Using Device Tree

The BME280 sensor is a versatile device that can measure temperature, humidity, and pressure. This tutorial will guide you through integrating the BME280 sensor in a Zephyr-based application using Device Tree. You’ll learn how to set up the sensor, read measurements, and handle configurations effectively.

Prerequisites

• Basic understanding of embedded systems.
• Familiarity with Zephyr RTOS.
• Installed Zephyr development environment.
• BME280 sensor module.
• Microcontroller board compatible with Zephyr (e.g., Nordic nRF52).

Parts/Tools

• BME280 sensor module
• Microcontroller board (e.g., Nordic nRF52)
• Zephyr SDK
• Visual Studio Code or another code editor
• Connecting wires

Steps

1. Connect the BME280 Sensor
   • Connect VCC to the 3.3V pin on your microcontroller.
   • Connect GND to the ground pin on your microcontroller.
   • Connect SDA to the I2C data pin on your microcontroller.
   • Connect SCL to the I2C clock pin on your microcontroller.
2. Create a New Zephyr Project
   • Open your terminal and navigate to your Zephyr workspace.
   • Create a new application directory:

     mkdir bme280_app && cd bme280_app

   • Initialize the Zephyr project:

     west init -l .

3. Configure Device Tree for BME280
   • Navigate to your project directory and create a Device Tree overlay file:

     touch bme280_app.overlay

   • Add the following configuration to the overlay file:

     
     &i2c0 {
         bme280: bme280@76 {
             compatible = "bosch,bme280";
             reg = ;
             label = "BME280";
         };
     };
                     

4. Update prj.conf for I2C and Sensor
   • Open the `prj.conf` file in your project directory.
   • Add the following lines to enable I2C and the sensor driver:

     
     CONFIG_I2C=y
     CONFIG_BME280=y
                     

5. Write the Application Code
   • Create a new source file named `main.c`:

     touch src/main.c

   • Add the following code to `main.c` to initialize the sensor and read data:

     
     #include 
     #include 
     #include 
     
     LOG_MODULE_REGISTER(bme280_app);
     
     void main(void) {
         const struct device *dev = device_get_binding("BME280");
         struct sensor_value temp, humidity;
     
         if (dev == NULL) {
             LOG_ERR("Could not find BME280 device!");
             return;
         }
     
         while (1) {
             sensor_sample_fetch(dev);
             sensor_channel_get(dev, SENSOR_CHAN_AMBIENT_TEMP, &temp);
             sensor_channel_get(dev, SENSOR_CHAN_HUMIDITY, &humidity);
     
             LOG_INF("Temperature: %d.%06d °C", temp.val1, temp.val2);
             LOG_INF("Humidity: %d.%06d %%", humidity.val1, humidity.val2);
             
             k_sleep(K_SECONDS(1));
         }
     }
                     

6. Build and Flash the Application
   • In the terminal, build the application:

     west build -b  .

   • Flash the application to your microcontroller:

     west flash

Troubleshooting

• Device Not Found: Ensure the I2C address is correct and the connections are secure.
• Incorrect Readings: Verify that the sensor is powered correctly and that the Device Tree configuration matches the physical connections.
• Build Errors: Check your `prj.conf` settings and ensure that all necessary drivers are included.

Conclusion

Integrating a BME280 environmental sensor into a Zephyr project using Device Tree is a straightforward process. By following this guide, you can set up your sensor to measure temperature and humidity effectively. Experiment with the readings and further expand your application to utilize additional features of the BME280 sensor.