International Journal of Advanced Computational Engineering and Networking, ISSN: 2320-2106,
Volume-1, Issue-10, Dec-2013
WIRELESS RECEPTION FOR MICROCONTROLLER BASED SENSOR NETWORKS 1
NAGESWARA LALAM, 2MAITRI SOMANI BANGARD
1
University Institute of Technology (UIT), 2Rajiv Gandhi Technological University, Bhopal, India Email:
[email protected],
[email protected]
Abstract— This paper presents the emergence of antennas with the development in the wireless technology. Communication with sensors is becoming part of our daily life. In this paper proposed a technique of data reception, data processing and data display. Understanding microcontroller and its use for this purpose were of prime importance in this application. Antenna forms a major component of any wireless transmission. A successful emerging trend in the wireless communication is the smart-antenna systems. A smart antenna system employs multi-element antenna arrays that can automatically adjust to a dynamic signal environment. Therefore design and fabrication of micro strip antennas was undertaken. HFSS is the industry wide software for design and simulation of such antennas. This software was therefore used to design the micro strip patch antenna. The frequency used for the designing of antenna was 0.9 Ghz. The performance of the antenna was checked for both direct feed and inset feed. Keywords— micro strip antennas, data reception, data processing and data display, wireless reception.
I.
INTRODUCTION
Wireless communication is the transfer of information over a distance without the use of enhanced electrical conductors or "wires". The distances involved may be short (a few meters as in television remote control) or long (thousands or millions of kilometers for radio communications). The mobile wireless communication industry has grown by orders of magnitude, fueled by Digital and RF circuit fabrication improvements, VLSI technology, and antenna miniaturization technologies which make portable wireless equipment small, economical and reliable, A successful emerging trend in the wireless communication is the smart-antenna systems [1]. A smart antenna system employs multielement antenna arrays that can automatically adjust to a dynamic signal environment. Smart antenna systems also provide a substantial increase in the channel capacity of wireless systems. They offer the ability to improve signal reception and signal detection. Due to the emergence of communication industry which has taken place over the last 60 years, antennas and their principles have been an important area of focus. Antenna can be incorporated in various geometries and in several applications [2]. Micro strip or planar antennas are suitable for compact wireless communications due to their size, compactness. These are printed on a dielectric substrate backed by a conducting ground plane, present an effective solution to the development of miniaturized structures [3]. As compared to the analog communication, digital communication is more advantageous and hence used for transmission and reception in the form of data packet with starts and stop bits. The digital data can be received as serial or parallel data through synchronous or asynchronous communication. The serial data is to be converted to parallel data. This job is done by the use of microcontroller.
Figure1: Block diagram of digital wireless reception and display of data
II.
HARDWARE DESIGN AND DESCRIPTION:
The microcontroller is a computer-on-a-chip that is often a part of the embedded system. It includes a processor core, memory and programmable input/output peripherals, but because they are designed to perform a specific task for a single system they are smaller and simplified so that they can include all the function that are required on a single chip [4]. The program is frequently stored on the microcontroller in an area of non-volatile memory. Microcontroller are used in automatically controlled products & devices, such as automobile engine control system, remote controls, office machines, appliances, power tools and toys. Generated the schematic of the circuit on Express SCH software. This helps to check the electrical connections and generate the bill of materials.
Figure 2: Schematic diagram showing LCD connections with microcontroller
Wireless Reception For Microcontroller Based Sensor Networks 49
International Journal of Advanced Computational Engineering and Networking, ISSN: 2320-2106,
Volume-1, Issue-10, Dec-2013
for driving a dot-matrix liquid crystal display are internally provided on one chip, a minimal system can be interfaced with this controller/driver [16]. A single HD44780U can display up to one 8-character line or two 8-character lines. The HD44780U has pin function compatibility with the HD44780S which allows the user to easily replace an LCD-II with an HD44780U. The HD44780U character generator ROM is extended to generate 208 5 ´ 8 dot character fonts and 32 5 ´ 10 dot character fonts for a total of 240 different character fonts. The low power supply (2.7V to 5.5V) of the HD44780U is suitable for any portable battery-driven product requiring low power dissipation [5].
Figure2: Pin Configuration of 8051
The 8051 is the original member of the 8051 family. Intel refers to it as MCS-51. It provides many functions (CPU, RAM, ROM, I/O, interrupt logic, timer, etc.) in a single package. The Port 1 is an 8-bit bi-directional I/O port. Port pins P1.2 to P1.7 provide internal pull-ups. P1.0 and P1.1 require external pullups. P1.0 and P1.1 also serve as the positive input (AIN0) and the negative input (AIN1), respectively, of the on-chip precision analog comparator. The Port 1 out-put buffers can sink 20 mA and can drive LED displays directly. When 1s are written to Port 1 pins, they can be used as inputs. When pins P1.2 to P1.7 are used as inputs and are externally pulled low, they will source current (IIL) because of the internal pullups. Port 1 also receives code data during Flash programming and verification. Port 3 pins P3.0 to P3.5, P3.7 are seven bi-directional I/O pins with internal pull-ups. P3.6 is hard-wired as an input to the output of the on-chip comparator and is not accessible as a general-purpose I/O pin. The Port 3 output buffers can sink 20 mA. When 1s are written to Port 3 pins they are pulled high by the internal pull-ups and can be used as inputs [6]. As inputs, Port 3 pins that are externally being pulled low will source current (IIL) because of the pull-ups. Reset input, all I/O pins are reset to 1s as soon as RST goes high. Holding the RST pin high for two machine cycles while the oscillator is running resets the device. Each machine cycle takes 12 oscillator or clock cycles. The XTAL1 and XTAL2 are the input and output, respectively, of an inverting amplifier which can be configured for use as an on-chip oscillator.
Figure 3: LCD-HD44780U
The HD44780U has pin function compatibility ith the HD44780S which allows the user to easily replace an LCD-II with an HD44780U. The HD44780U character generator ROM is extended to generate 208 5 ´ 8 dot character fonts and 32 5 ´ 10 dot character fonts for a total of 240 different character fonts. The low power supply (2.7V to 5.5V) of the HD44780U is suitable for any portable battery-driven product requiring low power dissipation.
Figure 4: LCD front View
2.1 Liquid Crystal Display The HD44780U dot-matrix liquid crystal display controller and driver LSI displays alphanumerics, Japanese kana characters, and symbols. It can be configured to drive a dot-matrix liquid crystal display under the control of a 4- or 8-bit microprocessor. Since all the functions such as display RAM, character generator, and liquid crystal driver, required
Figure 5: LCD back View
The LCD Module can easily be used with an 8051 microcontroller such as the P89V51RD2BN. The LCD Module comes with a 16 pin connector. This can be plugged into connector 16 pin [6].
Wireless Reception For Microcontroller Based Sensor Networks 50
International Journal of Advanced Computational Engineering and Networking, ISSN: 2320-2106,
Volume-1, Issue-10, Dec-2013
2.3 Radiation Mechanism of a Microstrip Antenna Radiation from microstrip antennas can be considering the simple case of a rectangular micro strip patch placed a small fraction of wavelength above the flat conducting plane. If we assume that there are no variation of the electric field along the width and the thickness of the micro strip structure. The field vary along the patch length which is approximately half the wavelength (λ/2) in conventional micro strip patches. Radiation can be mostly ascribed to the fringing fields at the open circuited edges of the radiator [14]. If the fringing fields are resolved into its parallel and tangential components with respect to the ground plane, the normal components would be out of phase with each other and therefore would cancel each other. In other words the normal components do not contribute to the far field radiation. The tangential components are in phase and the resulting tangential field components combine to give maximum radiated field normal to the surface of the patch, that is, the broadside direction [9]. Therefore, the patch may be represented by to slots λ /2 apart excited in phase and radiating in the half space above the ground plane.
Figure 6: Circuit showing LCD connection with microcontroller
2.2 Microstrip Patch Antenna A patch antenna (also known as a Rectangular Micro strip Antenna) is a popular antenna type. It consists of a single metal patch suspended over a ground plane. They are suitable for aircraft, satellite and missile application and wireless communication where size, weight, ease of installation, mechanical reliability and cost are important. The micro strip antennas are low profile, mechanically robust, inexpensive to manufacturing, compatible with MMIC designs and relatively light and compact. The assembly is usually contained inside a plastic radome, which protects the antenna structure from damage (as well as concealing its essential simplicity). Patch antennas are simple to fabricate and easy to modify and customize. The radiation mechanism arises from discontinuities at each truncated edge of the microstrip transmission line. The radiation at the edges causes the antenna to be slightly larger than its physical dimension electrically. In order to obtain a resonant condition at the antenna driving point, a shorter than a one-half wavelength section of microstrip transmission line is used. A patch antenna is generally constructed on a dielectric substrate, usually employing the same sort of lithographic patterning used to fabricate printed circuit boards [7]. Microstrip antennas have several advantages compared to the conventional antennas and therefore are used in many applications over a frequency range from approximately 100MHz to about 50GHz and higher [15]. A microstrip patch antenna in its simplest form consists of a radiating patch on one side of a dielectric substrate and a ground plane on the other side. The rectangular patch antenna is approximately a one-half wavelength long section of rectangular [microstrip] transmission line. When air is the antenna substrate, the length of the rectangular microstrip antenna is approximately onehalf of a free-space wavelength. As the antenna is loaded with a dielectric as its substrate, the length of the antenna decreases as the relative dielectric constant of the substrate increases [8]. The resonant length of the antenna is slightly shorter because of the extended electric "fringing fields" which increase the electrical length of the antenna slightly.
Figure 8: Radiation Mechanism of Microstrip Patch Antenna
2.4 Feeding Techniques The microstrip antenna can be excited directly by a coaxial probe or by a microstrip line. It can also be excited indirectly by using electromagnetic coupling or aperture coupling in which case there is no direct metallic contact between the feed line and the patch. Feeding technique influences the input impedance and a characteristic of the antenna is an important parameter. • Co-axial Feed In coaxial or probe feed, the center conductor of the coaxial connector is soldered to the patch. he main advantage of this feed is that it can be placed at any desired location inside the patch to match with its input impedance [7, 10]. The disadvantages are that the hole has to be drilled in the substrate and the connector protrudes outside bottom ground plane, so it is no more completely planar. This feeding arrangement also makes the configuration asymmetrical. • Inset Feed In microstrip line feed, the feed line is easy to fabricate, simple to match by controlling the inset feed position and relatively simple model. This feed arrangement has the advantage that it can be etched on the same substrate so the total structure remains planar. However as the substrate thickness increases,
Figure 7: Micro strip patch antenna
Wireless Reception For Microcontroller Based Sensor Networks 51
International Journal of Advanced Computational Engineering and Networking, ISSN: 2320-2106,
surface waves and spurious feed radiation increases, which leads to increase in cross polar level. Also in the millimeter wave range, the size of the feed line is comparable to the patch size, leading to increased undesired radiation.
3.1 Broadband Microstrip Patch Antenna Frequency= 0.9 GHz, €r = 4.4, h = 5mm, €r is the dielectric constant of the dielectric. Zi is the thickness of the item. Xi is the dimension in X direction and Yi is the dimension in Y direction Table 1: parametrics assigned for Inset feed
• Proximity or Electromagnetic Coupling The feed line is placed between the patch and the ground pane which is separated by two dielectric media. The advantages of this feed configuration are elimination of spurious feed network radiation, choice of having two different dielectric media, one for the patch and the other for fed line to optimize the individual performances, increase in band width due to increase in the overall substrate thickness of the microstrip antenna [11]. The disadvantages are that the two layers need to be aligned properly and the overall thickness of the antenna increases.
Figure 10: Smith Chart for Direct feed
• Aperture Coupling In aperture coupled configuration, the field is coupled from the microstrip line feed to the radiating patch through an electrically small aperture / slot cut in the ground plane. The coupling aperture is usually centered under the patch, leading to lower cross polarization due to symmetry of configuration. The shape, size and location of the aperture decide the amount of coupling from the feed line to the patch. The slot aperture can be either resonant or nonresonant. The resonant slot provides another resonance in addition to the patch resonance thereby increasing the bandwidth at the expense of increase in back radiation. So normally non resonant aperture is used. The performance is relatively insensitive to small errors in the alignment of the different layers. Similar to the proximity coupling method, the substrate parameters of the two layers can be chosen separately for optimum antenna performance [12]. III.
Volume-1, Issue-10, Dec-2013
Figure 11: Rectangular plot for patch antenna design
The above figures show the plots for patch antenna design. In the XY plot, the range varies from 0 to 1.2 GHz. As we only require plot at 0.9 GHz, this range can be decreased accordingly. It can be decreased to 0.7 to 1.2 GHz to get the required results. Same changes can be done in the Smith chart also. For obtain the best result, we changed the feed method. Now we used Inset feed in place of direct feed [13]. The following figure shows the microstrip patch design using inset feed.
RESULTS AND DISCUSSIONS
We designed a microstrip antenna on HFSS by using direct feed method. For impedance matching, position of feed line was varied and the result was calculated.
Figure 9: Window of patch antenna in HFSS
Figure 12: Microstrip Patch Design using Inset feed
Wireless Reception For Microcontroller Based Sensor Networks 52
International Journal of Advanced Computational Engineering and Networking, ISSN: 2320-2106,
3.2 Results for Inset feed Frequency= 0.9 GHz, €r= 4.4, h = 4mm, €r is the dielectric constant of the dielectric. Zi is the thickness of the item. In the above design, parametric solutions are assigned. Inset, microstrip lines are assigned as project variables. The values of the project variables are calculated as: Variable Value $Inset_Y 0.037-$DyInset $DyInset 12 $Feedlength 0.130-0.037+$DyInset Ground, patch, inset and feed line are assigned perfect E. the design is split using Boolean operation. On analysis the results are obtained as follows; The following figures show the rectangular plot and smith chart for the microstrip patch antenna using inset feed. The return loss is found -28 dB. Ansoft Corporation
REFERENCES [1]. A. Hande, T.Polk, W. Walker and D. Bhatia, “Indoor solar energyharvesting for sensor network router nodes”, Microprocessors and Microsystems, vol. 31-6, pp. 420-432, Sept. 2007. [2]. R.Morais, S. Matos, M. Fernandes, A.Valentea,S. Soares P. Ferreira and M. Reis,“Sun, wind and water flow as energy supply for small stationary data acquisition platforms”, Computers and Electronics in Agriculture, vol. 6-2, pp. 120-132, Dec. 2008. [3]. P. Mitcheson, E. Yeatman, G. Rao, A. Holmes and T. Green,“Energy Harvesting From Human and Machine Motion for Wireless Electronic Devices”, in Proc. IEEE, vol. 96-9, pp. 14571486, Sept. 2008. [4]. D. Arnold, “Review of Microscale Magnetic Power Generation”, IEEE Trans. Magnetics, vol. 43-11, pp. 3940-3951, Nov. 2007. [5]. X. Ma, H. Kobayashi and S. C. Schwartz, “Joint frequency offset and channel estimation for OFDM," of Global Telecommun. Conf., pp. 15-19, Dec. 2003.
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[6]. D. Albu, “On-node processing: Algorithms for Activity Classification and Monitoring in Wireless Sensor Networks,” M.S. thesis, Dept. of Math. and Comp. Science, Technische Univ. Eindhoven, Eindhoven, Netherlands, 2010 [7]. C. Mathuna, T. O'Donnell, R. Martinez-Catala, J. Rohan and B. O'Flynn, ”Energy scavenging for long-term deployable wireless sensor networks”, Talanta, vol. 75-3, pp. 613-623, May 2008.
dB(S(WavePort1,WavePort1)) Setup1 : Sw eep1 $DyInset='15mm' dB(S(WavePort1,WavePort1)) Setup1 : Sw eep1 $DyInset='13.5mm' dB(S(WavePort1,WavePort1)) Setup1 : Sw eep1 $DyInset='12mm' dB(S(WavePort1,WavePort1)) Setup1 : Sw eep1 $DyInset='10.5mm' dB(S(WavePort1,WavePort1)) Setup1 : Sw eep1 $DyInset='9.5mm'
[8] [4]. D. Arnold, “Review of Microscale Magnetic Power Generation”, IEEE Trans. Magnetics, vol. 43-11, pp. 3940-3951, Nov. 2007.
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[9]. D.Raskovic and D. Giessel, “Dynamic Voltage and Frequency Scaling For On-Demand Performance and Availability of Biomedical Embedded Systems”, IEEE Trans. on Inf. Tech. in Biomedicine, vol. 13-6, pp. 903 – 909, Nov. 2009.
Figure 13: Rectangular plot for Inset feed Ansoft Corporation
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[10]. Ye, W., J. Heidemenn, and D. Estrin, An Energy-Efficient MAC Protocol for Wireless Sensor Networks. 2001: Submitted for review, July 2001.
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[11]. J. K. Mikhaylov and J. Tervonen, “ Improvement of energy consumption for “over-the-air” reprogramming in Wireless Sensor Networks”, in Proc. ISWPC 2010, May 5-7 2010, pp. 86 – 92.
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[12]. M. Pedram,“Power optimization and management in embedded systems” in Proc. of Asia and South Pacific Design Automation, Jan. 30- Feb. 2 2001, pp. 239 - 244
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[13]. M. Sheets, F. Burghardt, T. Karalar, J. Ammer, Y. Chee, and J. Rabaey. A power-managed protocol processor for wireless sensor networks. In Proc. VLSI, June 2006.
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CONCLUSION
[14]. C. Knight , J. Davidson and S. Behrens, “Energy Options for Wireless Sensor Nodes”, Sensors, vol. 8, pp. 8037-8066, Dec. 2008.
In this paper, the objective of the project was to learn about Microstrip antenna design, HFSS software for high frequency simulation, Use of microcontroller, Express SCH or similar software for PCB schematic design, PCB fabrication process, Data processing and data display. This has been achieved. Thus the project has been successfully completed. Design and simulation of microstrip antenna was a great experience in developing 3D geometrical models also.
[15]. L. Nazhandali, M. Minuth, and T. Austin. Sensebench: toward an accurate evaluation of sensor network processors. An IEEE International Workload Characterization Symposium, October 2005. [16]. M. Hempstead, N. Tripathi, P. Mauro, G.-Y. Wei, and D. Brooks. An ultra low power system architecture for sensor network applications. In The 32nd Annual International Symposium on Computer Architecture (ISCA), June 2005
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