If you are interested in specific events, reading a sensor in regular intervals can be wasteful. Besides, some events may be missed if they happen outside the measurement window. Implement a low-energy event detection circuit and only generate a measurement if an event is detected.
You have a device with sensors built into it or attached to it and you need to use these sensors to acquire measurement and react to certain events.
You have a use case where you are interested in irregularly occurring events that are represented in sensor values. Reading the sensor in regular intervals is wasteful because those events occur rarely and the other values are of no interest to you. Besides, it is possible that you miss an event if it falls between two sensor readings.
Energy Requirements: Leaving sensors running all the time allows them to record detailed measurements but uses more energy.
Sampling: The events you are interested in can be of short duration but measuring them requires a high enough sampling rate.
Size: Measuring and sending many values over a long period enables detailed analysis but takes up storage space and communication bandwidth.
Knowledge: You do not always have prior knowledge about what you want to measure, but if you have, you can get better results by applying techniques specifically tailored to your use case.
Relevance: In some cases, only specific events are of relevance to you, but you do not need to collect all the other uninteresting measurements.
Define the events that are of interest to you in the form of sensor values. Use low-power sensors and power them continuously. Program low energy comparator circuits to read those sensors and watch for the events. Only propagate measurements to the device if a sensor value triggers such a comparator circuit.
- L. Reinfurt, U. Breitenbücher, M. Falkenthal, F. Leymann, and A. Riegg, “Internet of Things Patterns for Devices: Powering, Operating, and Sensing,” International Journal on Advances in Internet Technology, vol. 10, no. 3 & 4, pp. 106–123, 2017. Available at http://www.iariajournals.org/internet_technology/inttech_v10_n34_2017_paged.pdf