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STMicroelectronics
2018/10/31
Always-On Inertial Measurement Unit from STMicroelectronics Improves Accuracy, Optimizes System Power
Large onboard FIFO and faster serial interface let sensor work; system sleep
The LSM6DSO iNEMO™ Inertial Measurement Unit (IMU) from STMicroelectronics is an always-on 3D accelerometer and 3D gyroscope system-in-package that is, by itself, extremely power efficient and accurate. At the same time, the IMU makes the entire embedded system around it more power efficient, too.
Two key features play into this increased system-level power efficiency. The LSM6DSO contains a 9k-byte FIFO that can store significantly more data than comparable sensors and, as a result, allows the system processor to wait longer and make fewer requests for data. In addition, the LSM6DSO 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. 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 feature off-loads simple, repetitive tasks, further conserving system power.
The LSM6DSO emphasizes accuracy, too. It has a full-scale acceleration range of ±2 to ±16g and an angular rate range of ±125 to ±2000 dps. The sensors 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. Useful across a wide range of applications, these capabilities are particularly valuable for accurate motion detection and in 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%, reduction and contains a false-positive rejection block that recognizes bus, subway, and other conveyance movements to avoid counting them as steps. Moreover, the algorithm is highly configurable to enable tuning to specific user populations, depending on physical body parameters, further improving accuracy.
Further information is available at https://www.st.com//lsm6dso-pr
