# Installation

## System Prerequisites

smbus2 requires:

- **Linux** — the library uses Linux-specific `ioctl` calls and `/dev/i2c-*` devices.
- **I2C kernel support** — the `i2c-dev` kernel module must be loaded. On most
  distributions this is either built in or can be loaded with:

  ```bash
  sudo modprobe i2c-dev
  ```

  To load it automatically at boot, add `i2c-dev` to `/etc/modules`.

- **Device permissions** — the user running your Python script must have read/write
  access to `/dev/i2c-*`. The easiest way is to add the user to the `i2c` group:

  ```bash
  sudo usermod -aG i2c $USER
  # Log out and back in for the change to take effect
  ```

  Alternatively, run with `sudo` (not recommended for production).

## From PyPI

```bash
pip install smbus2
```

Installs the latest stable release. Use a virtual environment to avoid polluting the
system Python environment.

:::{note}
uv users can use `uv add smbus2` (uv-managed projects) or
`uv pip install smbus2` (ad-hoc virtual environments).
:::

## From conda-forge

```bash
conda install -c conda-forge smbus2
```

## From Source

```bash
git clone https://github.com/kplindegaard/smbus2.git
cd smbus2
python setup.py install
```

Or, using `pip` in editable mode (preferred for development):

```bash
pip install -e .
```

## Verifying the Installation

```python
python -c "import smbus2; print(smbus2.__version__)"
```

You can also verify that your I2C bus is accessible:

```python
from smbus2 import SMBus

with SMBus(1) as bus:
    print("Bus opened successfully")
```