navX2-Micro provides two methods for communicating with robotics control applications:
Streaming vs. Register-based Communication
The navX2-Micro interfaces fall into two types: Streaming and Register-based.
Streaming: data is sent at regular intervals by navX2-Micro, and the host is notified when new data arrives. The streaming data is sent in two different formats: Processed Data and Raw data. Streaming is used over the USB interface. More details on the communication detail are available in the Serial Protocol Definition.
Register-based: communication is initiated by the host whenever new data is desired, and the host can request any data required. Register-based communication is used over the I2C interface. More details on the communication detail are available in the Register Protocol Definition.
Comparing the navX2-Micro Communication Interfaces
| Interface Type | Speed | Latency | Type | Cable distance | Max Update Rate |
| USB | 12 mbps | <1ms | Streaming | 6 meters | 200 |
| I2C | 400 kbps | ~10ms | Register-based | 1 meter | 200 |
Recommendations
The USB interface is the recommended method for interfacing to navX2-Micro, based on for the higher communications bandwidth, lower latency and longer maximum cable distance.
[Update: 1/12/2022. For the 2022 FRC Season, the RoboRIO “onboard” I2C port has been reported to be unreliable. Therefore if using a RoboRIO, connect to the MXP I2C port, not the “onboard” I2C port until this is reported to be resolved.]
There are however a few cases where using the I2C interface is a reasonable option:
- When interfacing to a robot control systems which don’t support USB-connected sensors (e.g., the FTC Android-based REV Expansion or Control Hub).
- When already using the USB interface connection to a secondary processor (e.g., a video processor)