3.4. Inertial sensors

The Romi 32U4 Control Board includes on-board inertial sensors connected to the ATmega32U4’s I²C interface that can be used in advanced applications, such as helping detect collisions and determining the robot’s orientation. These sensors are part of the ST LSM6DS33, which combines a 3-axis accelerometer and 3-axis gyro into a single package.

The inertial sensors are connected to the board’s I²C bus by default, but they can be disconnected by cutting the surface-mount jumpers labeled “IMU SDA Jmp” and “IMU SCL Jmp”. Level shifters built into the control board allow the ATmega32U4, operating at 5 V, to communicate with the 3.3 V sensors. If a Raspberry Pi is plugged into the control board, its I²C pins are connected to the 3.3 V side of the bus as well. (See Section 3.7 for more information about the Raspberry Pi interface.)

We recommend carefully reading the LSM6DS33 datasheet (1MB pdf) to understand how these sensors work and how to use them.

Using the sensors

The Romi32U4 library (see Section 6) includes example programs that demonstrate how to use the sensors.