as sampling intervals as requirements change so that the fl exibility of software control is not sacrifi ced. By using a standard communications bus such as I2
the host microcontroller, the design team can take advantage of existing fi rmware libraries to manage the data fl ow from each of the sensors. This helps improve time to market for complex, multisensor designs.
Furthermore, the sensor module can be designed to buffer the recorded data until the host processor or memory subsystem is ready to receive the information. This results in less stringent timing requirements on the microprocessor’s software that often translates into the ability to use less frequent timer interrupts. Each time an interrupt occurs, it imparts an overhead that interferes with the speed of data-processing algorithms being executed by the main program. The result is that a lower-cost microprocessor can often be used in place of a part that is called upon to manage in fi ne detail the operation of all the sensor components. These changes can translate into lower system cost.
An important aspect of the conversion to digital output in the context of IoT applications is the use of tagging and metadata. In conventional system design, engineers make assumptions and choices about the use of sensor inputs. The data will be used in ways that are known well in advance. The fl exibility of the IoT, and its adaptiveness to as yet unknown applications, puts greater emphasis on the management of sensor data.
C or SPI to communicate with
In the IoT, the value of a pressure sensor lies not in its ability to record the current status of air or gas pressure. It is in the stream of data that it supplies within the context of readings taken by other pressure sensors, and the measurements of other parameters that are processed by IoT gateways or fog or cloud servers. For example, connected home appliances can combine pressure with temperature and other environmental signals to optimise heating and air conditioning. The additional context provided by IoT-relayed data makes it possible to take weather into account. Similarly, connected cars need not be restricted to monitoring just the operation of engine systems. They can relay information about local weather and road conditions. In turn, that contextual information can help optimise the real-time operation of functions within the car, such as slowing down internal air conditioning if the vehicle is moving towards a colder area.
Each measurement taken within the IoT is only useful if we know how, when and where that reading was taken. Therefore, a key role played by IoT sensor nodes will be to tag each recorded or processed sample that is to be relayed to the cloud with metadata that describes it and the conditions under which the measurement was taken. As a result, digitisation is fundamental to the growth of devices such as pressure sensors and will help drive the many markets for sensor nodes around the world. Many new applications await.
Technology review
Are you developing a new device or application that requires pressure measurement? Visit
avnet-abacus.eu/pressure-sensors to read our guide to choosing pressure sensors. You can also explore a range of additional resources to help you fi nd the right solutions for your design.
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