navX-Micro may be connected to the RoboRIO via several methods. Once you have selected your preferred communications interface, follow the appropriate installation instructions below.
One-wire Connect via USB cable
This preferred installation method allows the navX-Micro circuit board to be placed up to 6 meters away from the RoboRIO.
IMPORTANT NOTE: To avoid having the navX-Micro reset due to a RoboRIO brownout (as discussed further in the navX-Micro Best Practices), connecting the navX-Micro to the RoboRIO via USB is highly recommended.
The RoboRIO provides two separate I2C interfaces: the Onboard I2C interface, and the MXP Expansion Port I2C interface.
IMPORTANT NOTE: The left-to-right order of the RoboRIO Onboard I2C Interface Pins is different than the navX-Micro I2C pin left-to-right order. Pay careful attention to the I2C connector pin order when connecting navX-Micro to the RoboRIO.
RoboRIO Onboard I2C Interface
IMPORTANT NOTE: The left-to-right order of the RoboRIO Onboard I2C Interface Pins is different than the navX-Micro I2C pin left-to-right order.
RoboRIO MXP I2C Interface
As shown in the diagram below, the RoboRIO MXP Connector’s I2C-related pins are:
Pin 34: I2C SDA
Pin 32: I2C SCL
Pin 30: Digital Ground (DGND)
Pin 1: +5V (or +3.3V)
- The I2C bus standard requires that the SDA and SCL pins be pulled up with a pull-up resistor on each line. The RoboRIO internally pulls these lines high – but if connecting to a host computer without pullups, the SDA and SCL lines will need 1.5KOhm pullups.
- navX-Micro can be powered via it’s I2C connector with either 3.3V or 5V DC. A minimum of 3.1V DC is required.
- The navX-Micro I2C signal pins are 5V tolerant, so the host computer can use either 5V or 3.3V DC levels on these pins.