AltIMU-10 v4 Gyro, Accelerometer, Compass, and Altimeter

The Pololu Alt - IMU-10 v4 is an inertial measurement unit (IMU) and altimeter that features the L3GD20H gyro and LSM303D accelerometer and magnetometer and adds an LPS25H digital barometer. An I²C interface accesses ten independent pressure, rotation, acceleration, and magnetic ...The Pololu Alt - IMU-10 v4 is an inertial measurement unit (IMU) and altimeter that features the L3GD20H gyro and LSM303D accelerometer and magnetometer and adds an LPS25H digital barometer. An I²C interface accesses ten independent pressure, rotation, acceleration, and magnetic measurements that can be used to calculate the sensor’s altitude and absolute orientation.

The board operates from 2.5 to 5.5 V and has a 0.1′′ pin spacing. Notice:This board has been replaced by the Alt - IMU-10 v5, which features newer sensor ICs (the LIS3MDL 3-axis magnetometer and the LSM6DS33 3-axis accelerometer and gyro). The new v5 version is pin-compatible with the older v3 and v4 versions, but software written for the older versions will need to be rewritten to work with the v5.

Overview The Pololu Alt 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. The Alt - IMU-10 v4 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 LPS25H, L3GD20H, and LSM303D have many configurable options, including selectable resolutions for the barometer and dynamically selectable sensitivities for the gyro, accelerometer, and magnetometer. Each sensor also has a choice of output data rates. The three 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 Alt - IMUs connected on the same I²C bus (For additional information, see the I²C Communication section below). The nine independent rotation, acceleration, and magnetic readings provide all the data needed to make an attitude and heading reference system (AHRS), and readings from the absolute pressure sensor can be easily converted to altitudes, giving you a total of ten independent measurements (sometimes called 10DOF). With an appropriate algorithm, a microcontroller or computer can use the data to calculate the orientation and height of the AltIMU 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. The carrier board includes a low-dropout linear voltage regulator that provides the 3.3 V required by the LPS25H, 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 m - A 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 and 0.1′′ perfboards.

Specifications Dimensions: 1.0′′ × 0.5′′ × 0.1′′ (25 mm × 13 mm × 3 mm) Weight without header pins: 0.8 g (0.03 oz) Operating voltage: 2.5 V to 5.5 V Supply current: 6 m - A Output format (I²C): Gyro: one 16-bit reading per axis Accelerometer: one 16-bit reading per axis Magnetometer: one 16-bit reading per axis Barometer: 24-bit pressure reading (4096 LSb/mbar) Sensitivity range: Gyro: ±245, ±500, or ±2000°/s Accelerometer: ±2, ±4, ±6, ±8, or ±16 g Magnetometer: ±2, ±4, ±8, or ±12 gauss Barometer: 260 mbar to 1260 mbar (26 k - Pa to 126 k - Pa) Connections A minimum of four connections is necessary to use the Alt - IMU-10 v4: VIN, GND, SCL, and SDA. VIN should be connected to a 2.5 V to 5.5 V source, GND to 0 volts, and SCL and SDA should be connected to an I²C bus operating at the same logic level as VIN. (Alternatively, if you are using the board with a 3.3 V system, you can leave VIN disconnected and bypass the built-in regulator by connecting 3.3 V directly to VDD.) Pinout PIN Description SCL Level-shifted I²C clock line: HIGH is VIN, LOW is 0 V SDA Level-shifted I²C data line: HIGH is VIN, LOW is 0 V GND The ground (0 V) connection for your power supply.

Your I²C control source must also share a comm