💧 Kernel space driver for Bosch Sensortec BME280

The driver allows using the sensor via I2C bus on a single-board computer like Raspberry Pi, Orange Pi, Asus Tinker Board, etc.

🎉 Features

• 🗃️ Provides an interface in sysfs and procfs for sensor settings, calibration data, measurements
• ⚙️ Supports multiple sensors on the same I2C adapter
• 🔌 Supports multiple I2C adapters
• ⚗️ Tested on: Rasbperry Pi 3B+, Asus Tinker Board

🌻 Motivation

Final project for my education in Linux Kernel GL BaseCamp. I participated in the course from November 2019 until March 2020.

✨ Getting Started

📚 Prerequisites

Firstly you will need to install build dependencies such as compiler (build-essential, g++-arm-linux-gnueabihf, gdb-multiarch) and linux-headers. Next, you will need to get source code for exact kernel version you are running. You can find the kernel version via uname -r.

📦 Installation

1. Clone the Repository
2. Build this Kernel Module (make clean modules_release)
3. Install this Kernel Module (make modules_install)

👀 Usage

1. Connect the sensor to your host
2. Scan I2C bus to find the sensor address (i2cdetect)
3. Initialize the sensor from user space (echo "bme280 'your address, usually 0x76 or 0x77'" > /sys/bus/i2c/devices/i2c-'your adapter number'/new_device)

❓ FAQs

🙋‍♂️ How to access sensor settings, calibration data, measurements?

👉 sysfs – filesystem for exporting kernel objects

Mapping	Operations	Description
/sys/class/bme280/i2c	read/write	I2C adapter and device address
/sys/class/bme280/chip_id	read	Chip identifier
/sys/class/bme280/reset	write	Reset
/sys/class/bme280/mode	read/write	Power mode
/sys/class/bme280/osrs_p	read/write	Pressure oversampling
/sys/class/bme280/osrs_t	read/write	Temperature oversampling
/sys/class/bme280/osrs_h	read/write	Humidity oversampling
/sys/class/bme280/filter	read/write	Filter coefficient
/sys/class/bme280/standby_time	read/write	Standby time
/sys/class/bme280/pressure	read	Pressure (Pa)
/sys/class/bme280/temperature	read	Temperature (°C * 100)
/sys/class/bme280/humidity	read	Humidity (% * 1024)

👉 procfs – process information pseudo-filesystem

Mapping	Operations	Description
/proc/bme280info	read	Device information as a table
/proc/bme280calib	read	Calibration data as a table

🙋‍♂️ How to switch to another sensor?

👉 If you want to switch to another sensor, use /sys/bme280/i2c mapping, write to it a number of I2C adapter in decimal and device address in hex (echo "0 0x77" > /sys/bme280/i2c).

🛠️ Tech Stack

✍️ Contributing

👍🎉 First off, thanks for taking the time to contribute! 🎉👍

Contributions are what make the open source community such an amazing place to be learn, inspire, and create. Any contributions you make are greatly appreciated.

1. Fork the Project
2. Create your Feature Branch (git checkout -b feature/awesome-feature)
3. Commit your Changes (git commit -m 'Add awesome feature')
4. Push to the Branch (git push origin feature/awesome-feature)
5. Open a Pull Request

⚠️ License

lkmod-bme280 is licenced under the MIT License. See the LICENSE for more information.