Always-on IMU optimizes system power

By Alex Pluemer, contributing writer

STMicroelectronics recently introduced the LSM6DSO iNEMO inertial measurement unit (IMU), a highly accurate and power-efficient always-on 3D accelerometer and 3D gyroscope system-in-package.

Two key features contribute to the improved system-level power efficiency, according to ST. The new IMU features a 9-kB FIFO capable of storing more data than comparable sensors, thereby allowing the system processor to sleep longer and make fewer data requests. The LSM6DSO also features a combination MIPI I³ C and SPI/I² C serial interface. The MIPI I³ C interface provides dynamic address assignment and follower-initiated communication as well as communication speeds up to 10 times faster than I² C.

Faster and less frequent transmission results in the processor sleeping longer and lowers the system’s overall power consumption. The LSM6DSO also features an embedded programmable finite state machine, which offloads simple, repetitive tasks, further lessening the burden on the processor and conserving system power.

The IMU provides high-level accuracy, featuring a full-scale acceleration range of between ±2 g to ±16 g and an angular rate range of ±125 dps to ±2,000 dps. The sensors offer excellent overall noise performance with an acceleration noise density of 70 mg/√Hz and a rate noise density of 3.8 mdps/√Hz, as well as a configurable phase delay for OIS/EIS applications and typical ZRL of ±1 dps. These features make the LSM6DSO well-suited for enhancing camera performance and motion detection, as well as a variety of other applications.

In addition, the sensor implements an ST-developed pedometer algorithm that utilizes floating-point math to reduce step-counter errors by 60%. A false-positive rejection block recognizes train, bus, and subway movements and differentiates them from normal steps, reducing step-counter errors. The algorithm can be configured to enable tuning to particular user populations and their physical body parameters, thereby further enhancing accuracy.

The LSDM6DSO is priced at $1.99 for orders of 1,000 pieces.