ARM MICRO-CONTROLLER BASED MULTI -FUNCTION SOLAR TRACKING SYSTEM
In remote areas the sun is a cheap source of electricity because instead of hydraulic generators it uses solar cells to produce electricity. While the output of solar cells depends on the intensity of sunlight and the angle of incidence. The solar panels must remain in front of sun during the whole day. But due to rotation of earth those panels can’t maintain their position always in front of sun. This problem results in decrease of their efficiency. Thus to get a constant output, an automated system is required which should be capable to constantly rotate the solar panel. In this project we are implementing Automatic Sun tracking System on both sides. One side of automatic sun tracking system we have sensor network which track the position of sun and based on the position rotate the solar panel towards the direction where the intensity of sunlight is maximum and transmit the data to control remote system via wired or wireless medium. Based on the data received it gives the signal to stepper motor to rotate the large panel. The unique feature of this system is that instead of taking the earth as its reference, it takes the sun as a guiding source. The system can display the result on the LCD display. The primary objectives were compact design, efficient energy collection, and ability to monitor available battery charge status using ARM based Microcontroller and also provide to power supply for control system unit. In this project we are using ARM7TDMI based LPC2148 microcontroller to control the position of the solar panel ,which is having 64 pin capability ,512KB of Flash memory ,8 to 32KB of SRAM and many peripherals ,working with internal clock generation using PLLs up to 60 MHz . The application code will be developed in Embedded C language. Keil4 IDE software will be used to build the Hex file and flash magic is used to dump the GENERATED Hex file in to microcontroller.
A Microprocessor system consists of a microprocessor with memory, input ports and output ports connected to it externally. A microcontroller is a single chip containing a microprocessor, memory, input ports and output ports. Since all four blocks reside on one chip, a microcontroller is much faster than a microprocessor system. We have several other basic microcontroller families such as PIC, M68HCXX, AVR etc. .All these basic microcontrollers are useful for implementing basic interfacing and control mechanism for simple applications. There are several applications which require lot of computation and high speed data processing. In such applications advanced microcontrollers and microprocessors are used. One such advanced architecture is ARM. The ARM7TDMI core is a 32-bit embedded RISC processor delivered as a hard macro cell optimized to provide the best combination of performance, power and area characteristics. The ARM7TDMI core enables system designers to build embedded devices requiring small size, low power and high performance. The ARM7 family also includes the ARM7TDMI processor, the ARM7TDMIS processor, the ARM720T processor and the ARM7EJ-S processors, each of which has been developed to address different market requirements. The market for microprocessors continues to diversify, based on the evolving demands of applications including wireless, home entertainment, automotive and microcontrollers. ARM core families sharing the ARMv7 architecture will cover the widening spectrum of embedded processing. The ARM architecture is based on Reduced Instruction Set Computer (RISC) principles. The RISC instruction set and related decode mechanism are much simpler than those of Complex Instruction Set Computer (CISC) design.
The smart solar system is a self-powered system; all components of the system depend on each other’s, the system does not need any supply from the external world but only sun light. Those components interconnect with each other’s in order to form a closed system. The solar radiation gathered by the photovoltaic cell is transformed into electrical energy; the panel will feed the input of the charger which will charge a 12 Volt DC battery. The second functionality of the cell is to give precise voltage to the tracker, in order to reach the most efficient direction and orientation of the system which will allows maximum sunlight absorption. The battery will supply the system with a 12 Volt DC. The motors, the charger, the tracker and the sensors are supplied by the battery. Three photoresistors are used in the tracking system all are fixed on the upper part of the system near the photovoltaic cell in an X-O-Y manner as shown in figure c. It allows a reference photoresistors the one at position O which will be compared with the photoresistors X and Y and depending on the voltage output. The tracker will compare X and O positions, the comparison will end after a very near values of outputs of those two photoresistors are reached, a loop will control the stepper motor motion and steps till a near equality of sunlight distribution will be reached. After reaching an acceptable position and values for the X-O position test, the Y-O photoresistors are tested and compared in the same manner.
In this paper a universal multi-function solar tracker system is reported. The proposed system was implemented in reduced complexity architecture such as a microcontroller. The control system which is the brain of the proposed system is used to turn a small PV panel in three directions to determine the maximum output current. Three photo resistors are used every 45 minutes to redirect the PV panel to het the nearest value of the maximum sun.
. Honsinger, C.W., Jones, P., Rabbani, M., and Stoffel, J.C.: ‘Lossless recovery of an original image containing embedded data’. US patent no. 6278791, 2001
. Goljan, M., Fridrich, J., and Du, R.: ‘Distortion-free data embedding for images’. 4th Information Hiding Workshop, LNCS, vol. 2137, (Springer-Verlag, New York, 2001, pp. 27–41.
. Celik, M.U., Sharma, G., Tekalp, A.M., and Saber, E.: ‘Reversible data hiding’. Proc. ICIP, 2002, vol. 2, pp. 157–160
. Tian, J.: ‘Reversible data embedding using a difference expansion’, IEEE Trans. Circuits Syst. Video Technol., 2003, 13, (8), pp. 890–896.
. Xuan, G.R., Yang, C.Y., Zhen, Y.Z., and Shi, Y.Q.: ‘Reversible data hiding using integer wavelet transform and companding technique’.Proc. IWDW, 2004.
 J. Tian, “Wavelet-based reversible watermarking for authentication,” in Security and Watermarking of Multimedia Contents IV—Proc. SPIE, E. J. Delp III and P. W. Wong, Eds., Jan. 2002, vol. 4675, pp. 679–690.
 B. Macq, “Lossless multiresolution transform for image authenticating watermarking,” in Proc. EUSIPCO, Sept. 2000, pp. 533–536.