STMicroelectronics, a leading semiconductor supplier, has launched three new accelerometers with advanced processing engines built-in to extend sensor autonomy, enabling systems to respond more quickly to external events while lowering power consumption. The LIS2DUX12 and LIS2DUXS12 leverage ST’s third-generation MEMS technology, adding programmable capabilities including machine-learning core (MLC), advanced finite state machine (FSM), and an enhanced pedometer. A third entry-level accelerometer, LIS2DU12, is also available for less demanding applications.
An advanced finite state machine (FSM) is an extension of the traditional FSM model, which is a mathematical model used to describe the behavior of a system that can be in one of a finite number of states at any given time. The advanced FSM model includes additional features that allow for more complex behaviors to be modeled.
One of the key features of an advanced FSM is the ability to incorporate hierarchical states, which allow for the modeling of systems with multiple levels of abstraction. In a hierarchical FSM, each state can have its own internal FSM, enabling the modeling of complex behaviors that are composed of simpler behaviors.
Another feature of advanced FSMs is the ability to include concurrent states, which can represent multiple independent activities that occur simultaneously. This allows for the modeling of systems that have multiple components or processes that operate independently of one another.
Advanced FSMs can also include event-driven transitions, where a transition from one state to another is triggered by an external event. This allows for the modeling of systems that respond to external stimuli or user input.
All three products are equipped with the latest industry standard I3C interface. The three devices integrate the common digital features for detecting events, as well as an anti-aliasing filter for high accuracy at lower sampling frequencies with performance benefits for accurate gesture detection at negligible power consumption.
The I3C interface (pronounced “eye-three-see”) is a new, low-power, two-wire communication interface that was developed as an upgrade to the widely used I2C (Inter-Integrated Circuit) interface. I3C stands for “Improved Inter-Integrated Circuit”, and it was introduced by the MIPI Alliance, a global organization that develops interface specifications for mobile and mobile-influenced industries.
The I3C interface provides several advantages over the I2C interface, including:
Higher Data Rates: I3C supports higher data rates than I2C, up to 12.5 Mbps, compared to the maximum 3.4 Mbps of I2C.
Backward Compatibility: I3C is backward compatible with I2C, which means that I3C devices can communicate with I2C devices using the same two-wire bus.
Reduced Power Consumption: I3C uses a low-power mode called High-Speed Inactive (HSI) mode, which allows devices to operate in a low-power state while still being connected to the bus. This can significantly reduce power consumption in battery-operated devices.
Dynamic Address Assignment: I3C supports dynamic address assignment, which means that devices can be added or removed from the bus without the need for manual configuration.
Multi-Master Support: I3C supports multi-master operation, which allows multiple devices to initiate transactions on the bus at the same time.
The integrated MLC in the LIS2DUX12 and LIS2DUXS12 enables artificial-intelligence (AI) algorithms to perform reliable activity detection and the FSM enhances movement recognition. Together, they provide autonomous processing in the sensor, which offloads host interaction and processing, significantly lowering power consumption and enables faster system responses.
In addition, by deploying an adaptive self-configuration (ASC) capability, the accelerometers adjust their own settings (such as measurement range and frequency) independently to further optimize performance making each milliampere count. The LIS2DUXS12 also features ST’s unique Qvar® sensing channel that senses changes in the ambient electrostatic environment to provide presence and proximity detection.
This capability lets developers add value to applications such as user-interface control, liquid detection, and biometric sensing such as heart-rate monitors. In user-interface applications, Qvar® combined with an acceleration signal removes potential false positive detection in two-tap and multi-tap events.
The smart accelerometers provide context sensing for state-of-the-art wearables devices, True Wireless Stereo (TWS) speakers and earbuds, smartphones, hearing aids, game controllers, smart watches, asset trackers, robotic appliances, and IoT devices.
All three products leverage on ST’s latest ultra-low-power architecture, which combines inherently extremely low power consumption with the anti-alias filter that helps to boost application performance, removing unwanted noise from the signal. Ready-to-use MLC and FSM algorithms are available through ST’s MEMS GitHub model zoo, which facilitates complex gestures, asset tracking, and many other use cases.
