In part I of article, sensor unit was addressed with microcontroller as well as its brief applications.

Nonetheless, part II addresses vague technical analysis on possible low- cost peripherals interface with embedded system. Ideally, low –cost interfaces used to connect peripheral chips to microcontrollers residing in a unit of embedded systems.

However, sensors part II shall provide an insightful overview on gradual and brief achieve-able research works regarding sensor networks. Though, sensor networks still pose big challenges – communication protocols, routing as well as energy.  Besides, energy efficiency is a known issue which is indubitably remains a herculean task to telecommunication equipment and electronic products manufactures.

Meanwhile, this article surely not addresses areas of immaturity in wireless sensor networks which characterised as high- level concepts. Areas are databases, middleware and applications but tremendous and laudable development have been made on this, though still not fully matured.

 Peripheral Interfacing

The interfaces allow possible connection of distinct devices such as sensor interfaces, real – Time clocks. Due to affordability in terms of low –cost, interfaces are ideal for small embedded applications. The two available cheap interfaces:

1)      Serial Peripheral Interface acronyms as SPI

2)      Inter-integrated Circuit acronyms as I2C

1 Serial Peripheral Interface (SPI)

SPI is a protocol designed which employs synchronous (clock) transmissions.  Mode of operation works in master and slave relationship. Where by all transmissions with clock is usually produced by processor –microcontroller, master in this case. The receiving device, peripheral, a slave this time around employed clock for its synchronisation to accept the serial bit stream.

1        SPI can be used to interface to memory

2        Serial Peripheral Interface used in analogue digital converter and digital analogue converter

3        Use to interface sensor

4        Use to interface real –time clock calendars

2   Inter – Integrated Circuit (I2C)

Inter – Integrated circuit I2C is a network scheme employed to inter-connect peripheral devices in small scale embedded systems. IIC is a cheap network bus for effective communication with an embedded systems and peripheral.

Inter – integrated circuit is an alternative connection to SPI used in interfacing embedded systems with peripheral. IIC Operational mode quite distinct to SPI, I2C uses two wires connecting with numerous devices in a multi – drop bus. Conventionally, bus communicate in duplex, with considerable amount of low –speed and synchronous to a common clock.

Wireless Sensor Networks

In a traditional computer network communication, several computers networked together for sharing, distribution and storage of data. However, it is imperative to achieve better communication not only between computer and other devices but to also integrating computation and control in our physical environment. Communication is very crucial concept of interaction be it person –to – machine or machine – to –machine. And this communication concept takes the form of wired or wireless.

Wired communication is common for use among large numbers of devices that is imaginable in our environment. A MANET – Mobile Ad hoc Network is associated with wireless communication and specifically wireless multi-hop communication in case of computers connected in small networks.

Nonetheless, sensors can be integrated with processing unit, memory, communication device (low power radio) to what is commonly known as Sensor Node.  Several thousand of sensor nodes joining them together designed or built performing different applications wirelessly forming networks sensor. The type of wireless networks just appeared few years ago to handle sensor nodes deployment & physical interaction by sensing or controlling parameters.

More importantly, few years back the field of wireless sensor networks were at infancy stage; this indeed has opened to a plethora of research activities in the world leading universities and research institutions, among them, the fore- front university in innovations of wireless communication and its concept university of California, Berkeley USA, and as well as other top universities around the world where empirical analysis on wireless sensor networks have successfully been developed.

      Architecture of Sensor Node

The hardware assemble into a single- chip CMOS device that integrates the processing, storage, and communication sub-unit makes complete system node. The single sensor node is a very small size device measures 2.5mm by 2.5mm.

a)      Microcontroller

b)      Sensor board

c)      ADC

d)      General purpose I/O ports

e)      Memory – EEPROM

f)       Power Supply by battery

g)      Platform of sensor node range from different manufacturers such as Mica, Micaz, Rene, weC and many more.

Programming of sensor node is mostly achieved through what is called Network Embedded System C programming language otherwise known as nesC. nesC is a component based syntax OS specifically designed for sensor node, called TinyOS. However, subsequent article will address architecture of sensor node and its TinyOS.

Wireless Sensor Networks (WSN) Application Areas

Most research works in sensor networks today have partially be mined and matured to deploy few applications areas, such areas are:

a)       Facilities management – such as intruders into a large building,  real –time tracking – vehicles that pass a street outside of normal office hours.

b)      Medicine & health care – for intensive care where sensors attached to patients (elderly) and for automatic drug administration (embedding sensors into drug packaging, trigger an alarms whenever drugs applied to wrong patients.

c)      Monitoring of environmental condition for low frequency data trends – example a chemical factory could be easily be monitored for possible leakages by scores of sensors automatically networked wirelessly and write any detection of chemical leaks.

d)      Smart grid technology – sensor nodes could also be applied within an electric power distribution network – sensor and SCADA.

         Benefits of Wireless Sensor Networks

1. Wireless sensor networks use low cost embedded devices for different types of applications
2. Wireless sensor networks deployment independent on existing communication infrastructures – GSM, PSTN, Copper or Fiber.
3. No need of high power and expensive control mast or base stations.

Olawale Shakir Bakare

MSc Embedded Computer Systems Engineering UK, Sigbed Member US.

‘Wale Bakare also writes for EBN the premier online community for global supply chain professionals, EBN part of United Business Media Inc, USA.  Mr. Bakare also moderates for blogs with Internet Evolution Group – group that shares ideas and thoughts on internet technology and its developments. Internet Evolution is also a US based organisation, part of UBM Inc USA. And he belongs to member of Google group for Software Testing (QC) & Software Quality Assurance Group – software/embedded products testing technicians.

 Co – Founder PAWAAK Technologies Ltd

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