Issue link: https://resources.mouser.com/i/1442838
and therefore avoiding data loss and secure data acquisition for filtering or oversampling. FIFO buffer can work in several different modes for application flexibility reason. Event Recognition The majority of MEMS sensors come equipped with some additional fea- tures that can be used to generate interrupts when certain events occur. The events that can be recognized are free-fall (3-axes sub-threshold recogni- tion), wake-up (axis recognition), 6-D and 4-D orientation detection (change of position recognition), tap-tap (single, double, axis, and sign recog- nition), and wake to sleep (change of state recognition ACTIVE/SLEEP; also known as ACTIVITY/INACTIVITY). All these functions are in parallel and work smoothly at Output Data Rates (ODR) up to 1600Hz. Each event sets up an interrupt signal that may get driven to the dedicated interrupt pins of the device. Free-Fall: One of the early and ad- vantageous features embedded in MEMS accelerometer is the free-fall detection that can be used in many products to activate functions to protect the products from potential damage. A "free-fall zone" is de- fined around the zero-g level, where all acceleration values are small enough to generate the interrupt. The free-fall interrupt gets generated when the acceleration value on all three axes falls within the pre- defined free-fall zone (Figure 11). Activity/inactivity or wake-to-sleep and sleep-to-wake: Defined as the change of state recognition ACTIVE/ SLEEP. After the user has set an ODR, if the data of acceleration on the three axes are below a specified threshold for a specified duration of time, the device goes into Wake-to-Sleep mode. If the device is in sleep (inactivity) mode, when at least one of the axes exceeds the preset threshold, the device then goes into Sleep-to-Wake (as Wake-Up) mode. The threshold value is configurable which offers higher flexibility for vari- ous implementations. The 6D-4D orientation detection inter- rupts: The capability to detect the ori- entation of the device in the space, enabling smooth implementation of an energy-saving procedure and automatic image rotation for porta- ble devices. The interrupt then gets generated when the device switches from one orientation to another. 15 ST/Industrial Sensing Solutions Figure 9: Decision tree topology embedded in the latest inertial sensors Figure 10: Block diagram of the sensor hub functionality embedded in an IMU. Figure 11: Free-fall flow chart in an accelerometer.