MinIMU-9 v3 is a compact (0.8″ × 0.5″) breakout board that combines L3GD20H 3-axis gyroscope, and LSM303D 3-axis accelerometer and 3-axis magnetometer to form an inertial measurement unit (IMU) and altimeter. These sensors are great ICs, but their small packages make them difficult for the typical student or hobbyist to use. They also operate at voltages below 3.6 V, which can make interfacing difficult for microcontrollers operating at 5 V. MinIMU-9 v3 addresses these issues by incorporating additional electronics, including a voltage regulator and a level-shifting circuit, while keeping the overall size as compact as possible.
The L3GD20H, and LSM303D have many configurable options, including dynamically selectable sensitivities for the gyro, accelerometer, and magnetometer. Each sensor also has a choice of output data rates. The two ICs can be accessed through a shared I²C/TWI interface, allowing the sensors to be addressed individually via a single clock line and a single data line. Additionally, the SA0 pin is accessible, allowing users to change the slave addresses and have two MinIMU-9 v3s connected on the same I²C bus.
The nine independent rotation, acceleration, and magnetic readings provide all the data needed to make an attitude and heading reference system (AHRS). With an appropriate algorithm, a microcontroller or computer can use the data to calculate the orientation of the MinIMU-9 v3 board. The gyro can be used to very accurately track rotation on a short timescale, while the accelerometer and compass can help compensate for gyro drift over time by providing an absolute frame of reference. The respective axes of the two chips are aligned on the board to facilitate these sensor fusion calculations.
MinIMU-9 v3 includes a low-dropout linear voltage regulator that provides the 3.3 V required by the L3GD20H, and LSM303D, allowing the module to be powered from a single 2.5 V to 5.5 V supply. The regulator output is available on the VDD pin and can supply almost 150 mA to external devices. The breakout board also includes a circuit that shifts the I²C clock and data lines to the same logic voltage level as the supplied VIN, making it simple to interface the board with 5 V systems. The board’s 0.1″ pin spacing makes it easy to use with standard solderless breadboards.
Pololu Web Site: https://www.pololu.com/product/2468