I2C Bus

I2C is a packet-switched serial communication protocol that allows multiple master devices to connect to multiple slave devices using only 2 wires per connection. It is intended for attaching lower-speed peripheral ICs to processors and microcontrollers in short-distance, intra-board communication.

Pixhawk/PX4 support it for:

Connecting off board components that require higher data rates than provided by a strict serial UART, such as rangefinders.
Compatibility with peripheral devices that only support I2C.
Allowing multiple devices to attach to a single bus (useful for conserving ports). For example, LEDs, Compass, rangefinders etc.

:::note The page contains information about how to use (rather than integrate) I2C peripherals and solve common setup problems. :::

:::tip IMUs (accelerometers/gyroscopes) should not be attached via I2C (typically the bus is used). The bus is not fast enough even with a single device attached to allow vibration filtering (for instance), and the performance degrades further with every additional device on the bus. :::

Integrating I2C Devices

Drivers should #include <drivers/device/i2c.h> and then provide an implementation of the abstract base class I2C defined in I2C.hpp for the target hardware (i.e. for NuttX ).

A small number of drivers will also need to include headers for their type of device (drv_*.h) in - e.g. .

To include a driver in firmware you must add the driver to the board-specific cmake file that corresponds to the target you want to build for. You can do this for a single driver:

CONFIG_DRIVERS_DISTANCE_SENSOR_LIGHTWARE_LASER_I2C=y

You can also include all drivers of a particular type.

CONFIG_COMMON_DISTANCE_SENSOR=y

:::tip For example, you can see/search for CONFIG_DRIVERS_DISTANCE_SENSOR_LIGHTWARE_LASER_I2C in the configuration. :::

I2C Driver Examples

Just a few examples are:

Further Information

PreviousDroneCAN NextUART/Serial Ports

Last updated 1 year ago