Issue link: https://resources.mouser.com/i/1442838
17 ST/Industrial Sensing Solutions get integrated into any portable/wearable device. In an ac- celerometer-based pedometer, an accelerometer is used to measure the acceleration acting on the system during the walk/run through processing of acceleration data. Through this data, it is possible to detect each step and to determine how "soft/hard" each step is. Step detection is founded upon the recognition of accel- eration peaks. Acceleration signals measured via sensor are processed via a software program using dedicated algorithms. The software program checks the orientation of the device and chooses the dominant axis. The dominant axis is the axis with the maximum acceleration signal. One step is recognized when there is a positive peak that is im- mediately followed by a negative one. An interrupt signal gets generated when a step is detected. Self-Test One of the beneficial features embedded in MEMS sensors (accelerometers, gyroscopes,…) is the self-test. The self-test feature to determine whether the sensor is functioning after mounted on the final PCB can be used. It is a high- speed test, which saves time in production line and does not incur any additional cost as there is no need for any equipment for physical tilting or rotation of the PCB. The procedure may get accomplished by following a couple of simple steps. The sensor data acquisition takes place in both self-test and disabled conditions. The test may get performed at any stationary and arbitrary position. The first step is to power up and configure the device for regular operation, collect a few samples, average, and then save the data. The next step would be to enable the self-test feature first while the device powered up and then collect a few samples, average, and preserve it again. If the abso- lute value of these two average data is between the min and max values given, the datasheet indicates that the device is functioning, and real-time data may get collect- ed for further evaluation. Single Data Acquisition The amount of the data that the user can acquire through the sensors depends on the ODR, at which the device configured. For example, at an ODR of 100Hz, every 10ms new data would be available to read from the sensors. If a three-axis sensor with an output data format of 2 bytes gets employed, there would be 6 bytes of data every 10ms. If the raw data need to get transmitted to the cloud, there would be a massive amount of data that will get sent which would be time-consuming and costly, not to mention the security and the potential data corruption and confusion that are associated with data transfer to the cloud or a gateway. In certain situations, you might need a single data acquisi- tion to determine if there is any unexpected change in the health of a structure of the operation of a machine. Some of latest MEMS sensors have an embedded feature called one-shot mode that is used to execute single data acquisi- tions at the desired pace. The procedure of single data is effortless and straightfor- ward. First, the device has to get configured for a single data acquisition. The next step is to execute the single data acquisition and read data that are available in the output registers. Once the acquisition is completed and the output registers updated, the device automatically sets itself to power-down mode. The following diagram illus- trates a single data acquisition operation (Figure 14). Conclusion It has gotten demonstrated that MEMS technology delivers compelling industrial sensor solutions. ST is leading the way through innovation in miniaturization. ISM303DAC 3D Accelerometer & Magnetometer Module • Up to ±50 gauss magnetic dynamic range and dynamic switching between high-resolution, high- frequency, and low-power modes • Programmable interrupt generators for free-fall, motion, and magnetic field detection • Embedded 256-level FIFO and Embedded temperature sensor LEARN MOREu IIS2MDC 3-Axis Digital Magnetic Sensor • 3 magnetic field channels with Up to ±50 gauss magnetic dynamic range • Selectable power mode/resolution and single measurement mode up to 150Hz • Support for hard-iron compensation and Programmable interrupt generator LEARN MOREu