Overview

The EXT parameter group (specifically EXT_BUS) defines the hardware bus assignment for External Sensors.

Key Concepts

1. External Bus Selection

When using sensors that are not built-in to the flight controller (e.g., an external I2C Barometer or Compass), the autopilot needs to know which physical I2C bus to probe.

• Pixhawk/Cube: Usually Bus 1 (External 1) or Bus 2 (Internal).
• EXT_BUS: Manually overrides the autodetection if a sensor is plugged into a non-standard port.

Parameter Breakdown

• EXT_BUS: I2C Bus ID (0, 1, 2, 3).
  • -1: Autodetect (Standard behavior).

Developer Notes

• Library: libraries/AP_Baro (often aliased as BARO_EXT_BUS).