I2C Bus (Development Overview)

I2C 是一种分组交换串行通信协议，允许多个主设备连接到多个从属设备，每个连接只需使用2根电线。 它用于在短距离、板内通信中将低速外设 IC 连接到处理器和微控制器。

Pixhawk/PX4 支持：

• Connecting off board components that require higher data rates than provided by a strict serial UART, such as rangefinders.
• 与仅支持 I2C 的外围设备兼容。
• 允许多个设备连接到单个总线（有效保护端口）。 例如，LED、指南针、测距仪等。

注解

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

IMUs (accelerometers/gyroscopes) should not be attached via I2C (typically the [SPI](https://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus) 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.

集成 I2C 设备

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 here (opens new window)).

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

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:

drivers/sf1xx

You can also include all drivers of a particular type.

CONFIG_COMMON_DISTANCE_SENSOR=y

提示

For example, you can see/search for CONFIG_DRIVERS_DISTANCE_SENSOR_LIGHTWARE_LASER_I2C in the px4_fmu-v4_default (opens new window) configuration.

I2C 驱动程序示例

To find I2C driver examples, search for i2c.h in /src/drivers/ (opens new window).

Just a few examples are:

• drivers/distance_sensor/lightware_laser_i2c (opens new window) - I2C driver for Lightware SF1XX LIDAR.
• drivers/distance_sensor/lightware_laser_serial (opens new window) - Serial driver for Lightware SF1XX LIDAR.
• drivers/ms5611 (opens new window) - I2C Driver for the MS5611 and MS6507 barometric pressure sensor connected via I2C (or SPI).

更多信息

• I2C (opens new window)（维基百科）
• I2C 比较审查 (opens new window)（learn.sparkfun.com）
• 驱动程序框架