IEEE 1451 smart sensor: low cost, low power wireless case study

Wireless sensor networks (WSN) have been the object of study for some time, but the development of these networks has become more common a few years ago due to advances in the areas of microprocessors, sensing materials, micro electromechanical systems and wireless communications.

Today, it is usual to have cheap radio transducers incorporated with microcontroller units (MCU) which facilitates the rapid development of wireless devices. The replacement of traditional wired sensor networks for wireless ones has many advantages and allows the deployment in several different areas.

Among these are environmental applications, in which WSNs are used for monitoring environmental conditions. These networks can be used to the rapid detection of, for instance, points of fire in a forest, floods, monitoring animal’s movement or other environmental factors, such as detection of air pollution levels or pesticides in water.

In human health related applications, wireless sensor networks can be used for medical screening, monitoring patient’s movements, body functions (heart rate, blood pressure) and medicine administration. Other applicable areas include traffic control, modeling and monitoring structures, quality control of products, etc.

But the real promise of WSNs lies in their large scale deployment enabling applications previously only imagined in science fiction. Intelligent devices would be so small that they could remain suspended in the air, communicating for hours, days or even years.

But even with with the wide variety of protocols and manufacturers this task has become very complicated. Because of this drawback, IEEE in partnership with NIST created the IEEE 1451 standard to facilitate these operations.

This paper presents the development of a smart sensor based on the IEEE 1451. The developed device is composed of two parts: the sensor nodes and network node. Communication between these two parts is accomplished through a wireless interface using the IEEE 802.15.4 protocol. The main features of the developed smart sensor are its ability of self-configuration, self-calibration and self-identification when connected to the network.

The hardware selection for the development of an IEEE 1451 smart sensor is based on the need for a wireless interface between the network node and the sensor node. Concerning platforms that include MCU and radio in the same chip, there are several options, among them, the Freescale’s MC1322X.

This platform includes an ARM 7 MCU and an IEEE 802.15.4 radio, besides standard peripherals such as a 12 bit ADC with multiple inputs. These features are quite adequate to the development of a low cost, low power IEEE 1451 smart sensor.

Within the context of this work, the inclusion of IEEE 1451 in a smart sensor revealed not to be a very complex task but very time consuming. That is because of a large amount of information needed for the Transducer Electronic Data Sheet (TEDS) and also the number of commands that must be inserted into the sensor.

The employed hardware included a wireless communication interface and enough memory to allocate the TEDS and the routine operation of the sensor. In short, it is possible to afirm that IEEE 1451 family of standards is a standard not yet widely used due to their recent time of publication, but with a great potential for wide application.

To read this external content in full, download the complete paper from the open online author archives at the Federal University of Rio Grande do Sul Porto Alegre .

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