LSM6DS3

The LSM6DS3 offers multiple power modes: High-performance mode (combo) consumes 1.25mA at 1.6kHz ODR; Normal mode (combo) consumes 0.9mA; Accelerometer-only mode consumes 130uA at 52Hz ODR; Power-down mode consumes 3uA. The embedded features (pedometer, tilt, free-fall) can run while the main MCU sleeps, enabling significant system power savings. The machine learning core adds only 20uA when active. For always-on step counting, the 130uA mode enables years of battery life from a coin cell.

Use accelerometer-only mode for always-on applications. Enable combo mode only when motion tracking is needed.

The LSM6DS3 provides excellent accuracy for consumer applications: Accelerometer zero-g offset is ±40mg typical, enabling ±2° tilt accuracy; Gyroscope zero-rate offset is ±10dps typical, with excellent stability over temperature; Combined with sensor fusion algorithms, it provides 1-2° accuracy for static orientation and good relative tracking for dynamic motion. For higher accuracy requirements, consider adding a magnetometer (9-axis fusion) to correct gyroscope drift. The device is factory calibrated, eliminating the need for user calibration in most applications.

Sufficient for consumer applications. Add magnetometer for absolute heading reference in navigation applications.

The embedded machine learning core runs decision tree algorithms for gesture and activity recognition without host processor intervention. It can classify up to 8 different activities/gestures using data from the IMU and up to 4 external sensors. ST provides the Machine Learning Core (MLC) tool to train custom decision trees using labeled data. Once trained, the decision tree runs entirely in the sensor, consuming only 20uA. The host MCU is only woken when a recognized gesture occurs, enabling dramatic power savings for always-on gesture interfaces.

Use MLC for always-on gesture recognition. Train custom decision trees for your specific application.

The LSM6DS3 sensor hub can connect up to 4 external sensors (magnetometer, pressure, humidity) via I2C and automatically synchronize their data with the IMU data. The hub reads external sensors at configurable intervals and stores data in the FIFO alongside IMU data with common timestamps. This eliminates the need for the host MCU to manage multiple sensors, reducing software complexity and power consumption. The hub supports automatic sensor discovery and configuration. Data from all sensors can be read in a single burst transaction.

Use sensor hub to simplify multi-sensor designs and reduce host MCU workload.

The LSM6DS3 includes an 8KB FIFO that can store up to 9 seconds of 6-axis data at 100Hz. The FIFO enables batching of sensor data, allowing the host MCU to sleep longer between reads. For example, instead of waking every 10ms to read data, the MCU can sleep for 1 second and read 100 samples at once. The FIFO supports multiple operating modes including continuous, stop-on-full, and stream-to-FIFO. Watermark and overrun interrupts notify the host when data is ready or when FIFO is near full.

Use FIFO with watermark interrupt to maximize host MCU sleep time and minimize power consumption.

The LSM6DS3 supports both I2C (up to 400kHz Fast-mode) and SPI (up to 10MHz) interfaces. I2C uses 2 wires (SDA, SCL) with address 0x6A (SDO=0) or 0x6B (SDO=1). SPI uses 4 wires (MOSI, MISO, SCK, CS) and offers higher data rates suitable for maximum ODR. Two interrupt pins (INT1, INT2) can be configured for data ready, FIFO events, or embedded function interrupts (step detection, free-fall). ST provides drivers for STM32 platforms and register-compatible APIs across the LSM6 family. The device operates from 1.71V to 3.6V, compatible with most modern MCUs.

Use I2C for simplicity. Use SPI for highest data rates. Use interrupts for event-driven applications.