--- layout: page title: "Enable HassOS i2c" description: "Instructions on how to enable I2C on a Raspberry PI for Hass.io." date: 2018-01-11 20:08 sidebar: true comments: false sharing: true footer: true --- Hass.io is a managed environment, which means you can't use existing methods to enable the I2C bus on a Raspberry Pi. If you're attempting to add an external sensor, you will have to [enable the I2C interface in the Hass.io configuration](https://github.com/home-assistant/hassos/blob/dev/Documentation/boards/raspberrypi.md#i2c) using a USB stick. ## Step by step instructions You will need: - USB drive - A way to add files to the USB drive - A way to connect the drive to your Raspberry Pi ### Step 1 - Prepare the USB drive Connect the USB drive to a device capable of adding and editing files to the USB drive. Format a USB stick with FAT32/EXT4/NTFS and name the drive `CONFIG` (uppercase). ### Step 2 - Add files to enable I2C - In the root of the USB drive add a folder called `/modules`. - Inside that folder add a text file called `rpi-i2c.conf` with the following contents: ``` i2c-bcm2708 i2c-dev ``` - In the root of the USB drive add a file called `config.txt` with the following contents: ``` dtparam=i2c1=on dtparam=i2c_arm=on ``` ### Step 3 - Load the new USB config - Insert the USB drive into your Raspberry PI. - Now go to your Home Assistant web interface, in the sidebar click **Hass.io** > **System**. - Now click `Import from USB`. - This will restart your Hass.io instance, and load the new USB configuration. When the service has restarted, you will have a working I2C interface.