Always-on IMU improves accuracy, says STMicroelectronics

The LSM6DSO iNEMO inertial measurement unit (IMU) is an always-on 3D accelerometer and 3D gyroscope system-in-package (SiP) that is not only power efficient and accurate, but makes the entire embedded system around it more power efficient, too, says STMicroelectronics.

The LSM6DSO contains a 9kbyte FIFO that can store significantly more data than comparable sensors, explains STMicroelectronics, and as a result, allows the system processor to wait longer and make fewer requests for data. In addition, it adds a MIPI I3C serial interface to a serial peripheral interface (SPI) / I2C. The higher speed MIPI I3C interface offers dynamic address assignment, follower-initiated communication, and communication speeds about 10x faster than I2C, claims the company. By transmitting data faster and less frequently, the LSM6DSO lets the processor sleep longer and the system to use less power.

An embedded programmable finite state machine with the LSM6DSO also contributes to reducing the processor’s workload. This off-loads simple, repetitive tasks, further conserving system power.

A full-scale acceleration range of ±2 to ±16g and an angular rate range of ±125 to ±2000 dps ensures accuracy. The sensors are claimed to deliver best-in-class overall noise performance with acceleration noise density 70 mg/√Hz, rate noise density (RND) of 3.8mdps/√Hz and configurable phase delay for OIS / EIS application and typical ZRL of ±1dps. These capabilities are particularly useful for accurate motion detection and boosting camera performance.

The sensor also supports an enhanced ST-developed pedometer algorithm that uses floating-point math to reduce step-counter errors by 60 per cent, and contains a false-positive rejection block that recognises bus, trains and other movements to avoid counting them as steps. The algorithm is configurable and can be tuned to specific user populations, depending on physical body parameters, further improving accuracy, says ST.

The LSM6DSO is available now.