Shakeel Tariq

INSTITUTE OF SPACE TECHNOLOGY Design and Implementation of GSM Based Embedded Weather Station By Muhammad Shakil Tariq Sarmad Tahir A PROJECT SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF BACHELOR OF SCIENCE IN ELECTRICAL ENGINEERING Project Supervisors: Sir Tariq Mehmood Sir Abdul Haseeb Project 1st Supervisor’s Signature: Project 2nd Supervisor’s Signature: Islamabad, Pakistan July 2015 Certificate This is to certify that the research work described in this thesis is the original work of the authors and has been carried out under our direct supervision. We have personally gone through all the data/results/materials reported in the manuscript and certify their correctness/authenticity. We further certify that the material included in this thesis is not plagiarized and has not been used in part or full manuscript already submitted or in the process of submission in partial/complete fulfillment of the award of any other degree from any institution. We also certify that the thesis has been prepared under our supervision according to prescribed format and we endorse its evaluation for the award of Bachelor of Science in Electrical Engineering degree through the official procedures of the Institute. (Brig. Tariq Mehmood) -------------------------------- (Dr. Abdul Haseeb) ---------------------------------------- i Copyright © 2015 This document is jointly copyrighted by the authors and the institute of space technology (IST). Both author(s) and IST can use, publish or reproduce this document in any form. Under the copyright law, no part of this document can be reproduced by anyone, except copyright holders, without the permission of the author(s). ii DEDICATION TO MY PARENTS, TEACHERS AND FRIENDS Muhammad Shakil Tariq TO MY PARENTS, TEACHERS AND FRIENDS Sarmad Tahir iii Abstract Climate variables play an important role in many domains such as industry, military, entertainment and agricultural. These variables include air temperature, humidity, air Pressure, wind speed, wind direction, wind density, amount of rain, dew point, precipitation etc. This project represents the work on the design and implementation of GSM based weather data acquisition station. The station consists of three sensors; temperature, pressure and humidity and three assembles; wind direction, wind speed and rain gauge. On board processing is done through microcontroller and data is saved in SD card. Station is situated in a remote area and all the data controlling is done through a GSM module and reading is displayed on a computer screen. iv Acknowledgements First of all “All praise and thanks to almighty Allah alone, the sustainer of all the worlds without whom we are nothing”. We are also very thankful to our supervisors, Sir Tariq Mehmood and Sir Abdul Haseeb and kind teachers, Sir Moazzam Maqsood and Mam Saima Siddiqui for their constant support, encouragement and supervision during our complete project. It has been great honor and privilege for us to work with them. I (M. Shakil Tariq) would also like to pay my gratitude to Sir Umair and Sir Sajjad who did a lot of help during my work on hardware in workshop. I learned a lot from them. Last but not least our sincere thanks to our Parents who made us what we really are today. Without their support, it was impossible to complete the task. We would also like to thank all those friends and family members who stood with us and helped us in every difficult moment. v Table of Contents Certificate ............................................................................................................................. i Copyright © 2015 ............................................................................................................... ii DEDICATION ................................................................................................................... iii Abstract .............................................................................................................................. iv Acknowledgements ............................................................................................................. v Table of Contents ............................................................................................................... vi List of Figures ..................................................................................................................... x List of Tables .................................................................................................................... xii 1. Chapter 1: INTRODUCTION................................................................................. - 1 1.1 Problem Statement ........................................................................................... - 1 - 1.2 Objectives ......................................................................................................... - 1 - 1.3 Application ....................................................................................................... - 2 - 1.3.1 Weather Monitoring .................................................................................. - 2 - 1.3.2 Agriculture ................................................................................................ - 2 - 1.3.3 Industry ..................................................................................................... - 2 - 1.3.4 Poultry Farms ............................................................................................ - 2 - 1.3.5 Oceanography ........................................................................................... - 2 - 1.3.6 Transportation ........................................................................................... - 2 - 1.4 Deliverables ...................................................................................................... - 3 vi 1.5 Resources Used ................................................................................................ - 3 - 1.5.1 Hardware ................................................................................................... - 3 - 1.5.2 Workshop Machines ................................................................................. - 4 - 1.5.3 Software .................................................................................................... - 4 - 2. Chapter 2: Literature Review .................................................................................. - 5 - 3. Chapter 3: System Block Diagram ......................................................................... - 6 - 4. Chapter 4: Hardware ............................................................................................... - 8 4.1 PIC 18F4620 Microcontroller .......................................................................... - 9 - 4.1.1 PIC 18F4620 Pin Configuration ............................................................. - 10 - 4.1.2 Specification ........................................................................................... - 11 - 4.1.3 PIC 18F4620 Oscillator Configuration ................................................... - 12 - 4.2 Wind Direction Sensor ................................................................................... - 13 - 4.2.1 Grey Encoder .......................................................................................... - 13 - 4.2.2 Code Assignment .................................................................................... - 14 - 4.2.3 Mechanism Illustration ........................................................................... - 16 - 4.2.4 Circuit Simulation ................................................................................... - 16 - 4.2.5 Hardware Development .......................................................................... - 18 - 4.2.6 Software Development............................................................................ - 19 - 4.2.6.1 Programing of Wind Directions .......................................................... - 20 - 4.2.6.2 Simulation of Wind Directions ........................................................... - 21 vii 4.3 Wind Speed Sensor ........................................................................................ - 22 - 4.3.1 Principle .................................................................................................. - 23 - 4.3.2 Mechanism .............................................................................................. - 23 - 4.3.3 Disc ......................................................................................................... - 24 - 4.3.4 Circuit simulation.................................................................................... - 25 - 4.3.5 Hardware Development .......................................................................... - 27 - 4.3.5.1 Electrical Hardware ............................................................................. - 27 - 4.3.5.2 Mechanical Hardware ......................................................................... - 28 - 4.3.5.3 Finalized Hardware ............................................................................. - 28 - 4.3.6 Mathematical Formulation ...................................................................... - 29 - 4.3.7 Software Development............................................................................ - 30 - 4.3.7.1 Timer-1 Module of PIC 18F4620 ....................................................... - 31 - 4.3.7.2 Programing of Wind Speed ................................................................. - 31 - 4.3.7.3 Simulation of Wind Speed Mechanism ............................................... - 33 - 4.4 Rain Gauge ..................................................................................................... - 34 - 4.4.1 Principle-Tilt Bucket Mechanism ........................................................... - 34 - 4.4.1.1 Function of Cones ............................................................................... - 34 - 4.4.1.2 Function of Buckets ............................................................................ - 35 - 4.4.1.3 Reed Switch......................................................................................... - 36 - 4.4.2 Measurements ......................................................................................... - 37 viii 4.4.3 Finalized Hardware ................................................................................. - 38 - 4.4.4 Software development of Rain Gauge .................................................... - 38 - 4.4.4.1 Coding of Rain Fall ............................................................................. - 39 - 4.4.4.2 Simulation of Rain Fall Mechanism ................................................... - 41 - 4.5 5. 6. Finalized PCB for All Three Sensors and LCD ............................................. - 41 - Chapter 5: Structure .............................................................................................. - 43 5.1 Main Tripod.................................................................................................... - 43 - 5.2 Hive for Electronic Circuitry.......................................................................... - 44 - 5.3 Base for Anemometer..................................................................................... - 45 - 5.4 Base for Rain Gauge ...................................................................................... - 45 - 5.5 Finalized structure .......................................................................................... - 46 - References ............................................................................................................. - 47 - ix List of Figures Figure 1 : System Block Diagram of Ground Station ..................................................... - 7 Figure 2: Hardware Division .......................................................................................... - 9 Figure 3: Pin Configuration of PIC 18F4620 ............................................................... - 10 Figure 4: Crystal Oscillator Circuit............................................................................... - 12 Figure 5: Implementation of Crystal Oscillator ............................................................ - 12 Figure 6: Wind Direction Assembly ............................................................................. - 13 Figure 7: Disc of Grey Encoder .................................................................................... - 14 Figure 8: Angle Illustration ........................................................................................... - 16 Figure 9: Mechanical Illustration .................................................................................. - 16 Figure 10: Multisim Circuit for one IR Pair (Not Transmitting) .................................. - 17 Figure 11: Multisim Circuit for one IR Pair (Transmitting) ......................................... - 17 Figure 12: Simulations of 4 IR Pairs............................................................................. - 18 Figure 13: Hardware Illustration ................................................................................... - 19 Figure 14: Finalized Wind Direction Sensor ................................................................ - 19 Figure 15: LM339 Pin Configuration ........................................................................... - 20 Figure 16: Proteus Simulation for Wind Direction ....................................................... - 22 Figure 17: Anemometer Cups Arrangement ................................................................. - 22 Figure 18: Mechanism of Wind Speed Measurement................................................... - 24 Figure 19: Rotating Disc ............................................................................................... - 24 Figure 20: Multisim Simulation for Anemometer (No Contact between IR) ............... - 25 Figure 21: Multisim Simulation for Anemometer Contacted IR) ................................. - 26 Figure 22: Oscilloscope Results of Simulations ........................................................... - 26 - x Figure 23: Circuit Implementation of Anemometer on PCB ........................................ - 27 Figure 24: Mechanical Implementation of Anemometer .............................................. - 28 Figure 25: Finalized Anemometer ................................................................................ - 29 Figure 26: Configuration Register of Timer-1 .............................................................. - 31 Figure 27: Proteus Simulation for Wind Speed Mechanicm ........................................ - 33 Figure 28: Cones of Rain Gauge ................................................................................... - 35 Figure 29: Tilted Buckets.............................................................................................. - 35 Figure 30: Schematic of Tilt Bucket Mechanism ......................................................... - 36 Figure 31: Reed Switch Implementation ...................................................................... - 37 Figure 32: Finalized Rain Gauge .................................................................................. - 38 Figure 33: Proteus Simulation for All three Sensors .................................................... - 41 Figure 34: Finalized PCB of Weather Station .............................................................. - 42 Figure 35: Tripod .......................................................................................................... - 44 Figure 36: Wooden Hive ............................................................................................... - 44 Figure 37: Base of Anemometer ................................................................................... - 45 Figure 38: Finalized Structure ...................................................................................... - 46 - xi List of Tables Table 1 Specification of PIC 18F4620 ....................................................................................... - 11 Table 2 Code Assignment of Grey Encoder .............................................................................. - 15 - xii 1. Chapter 1: INTRODUCTION ________________________________________________________________________  Problem Statement  Objectives  Applications  Deliverables  Resources Used ________________________________________________________________________ 1.1 Problem Statement Weather stations are already available in market but problem is that they are static, huge and expensive so we designed a portable weather station which is cheap as well as reliable and can give flexible usage depending upon situation and application. 1.2 Objectives Our main objective was to replace old, static, gigantic, and less efficient weather station with a new, reliable, fast and smart weather station which takes less power and gives more accuracy in the readings. Our aim also includes the replacement of expensive monitoring stations in different industries and agricultures. This system can easily collect, process, store and transmit the data to ground station. -1- 1.3 Application This weather station has following applications. 1.3.1 Weather Monitoring  Its main application is weather forecasting and weather monitoring  Record the temperature and pressure fluctuation.  Record the climatic changes 1.3.2 Agriculture  1.3.3 Temperature and humidity conditions monitoring for crops and plants Industry  Monitoring of different processes which are sensitive to environment conditions like temperature and pressure. 1.3.4 Poultry Farms  Poultry farms include the monitoring of environment conditions for proper growth of chick and animals. 1.3.5 Oceanography  Coastal weather conditions monitoring and marine weather monitoring require a weather station. For example in Tsunami warning and flood warning situation we require a weather station. 1.3.6 Transportation  Weather data log for flights  Monitoring the aviation weather  Monitoring the road weather -2- 1.4 Deliverables Our project deliverables are listed below.  Development of anemometer which includes the measurement of wind speed and wind direction  Study and configuration of Rain gauge which uses a tilt bucket mechanism  Development of remote module consisting of temperature, pressure, humidity, wind speed, wind direction and rain sensor interfaced with PIC microcontroller and displaying data on 4x16 LCD.  Making log of measurements.  Transfer of data using GSM module.  Reception of data, using GSM module and display on LCD or using mobile phone and display on mobile screen. 1.5 Resources Used Resources which are used during our work are listed below. 1.5.1 Hardware  Microcontroller PIC 18F4620  4x16 LCD  IR Transmitter-Receivers  Aluminum Sheets, Plates and rods  Temperature Sensor DS1821  Humidity Sensor HS1101  Pressure Sensor BMP085 -3-  1.5.2 GSM modem SIM908 Workshop Machines  Lath Machine  Milling Machine  Grinding Machine  Drilling Machine  Tappers  Bench Grinders 1.5.3 Software  Proteus ISIS  Proteus Ares  Multisim 11.0  MikroC Compiler -4- 2. Chapter 2: Literature Review We have studied concerning research papers and a thesis of previous research on this topic. The research papers we have studied give us knowledge about previously made weather stations. Most of the automatic weather stations were based on the central control unit more specifically the microcontroller. The system makes more accurate readings and takes fewer resources to build the station. Traditional weather stations used to be very big and static. They used to be on a particular place not moveable and they used to need a big building to perform their full functions. They were slow because they used low speed processors. Their readings were not very accurate because a huge number of that station were to be implanted in a particular space to get the more climatic data which can give accurate results. As building such huge stations in a big number is not so economical so it was quiet impossible to build the network of such stations. So a low cost, portable, high speed, accurate and module based weather station was the need of time. In current time this need is felt by many researchers so they do a lot of work on it. We read their work and got some knowledge. By using that knowledge we tried to make our hardware which is summarize in next few pages. Some good papers are also attached as appendix-A from which we have taken the main idea of our work. These papers were quiet effective for us to define the methodology of our work. -5- 3. Chapter 3: System Block Diagram This project consists of collecting, storing and transmitting of data from different sensors which are placed on a remote location. Basically we had to measure the six climatic parameters so we needed six different sensors. These variables include air temperature, air pressure, air humidity, wind speed, wind direction, and rain fall. Three of the above mentioned variable can be measured from market available sensors, while other three had to be measured from handmade instruments. So we bought the temperature sensor (DS1821), Pressure sensor (BMP085), humidity sensor (HS1101) from the market and made the wind direction sensor, wind speed sensor, rain fall sensor in the lab. After that we interfaced them with microcontroller and interfaced them with the microcontroller and showed the value on 4x16 LCD. After collection of data we had to save the data in some sort of memory stick to make the log of that data to be used in the future. And at the end we had to send all the data in the form of an SMS through a GSM module. At the base station we had two options for collecting data either we dah to receive the massage data through a GSM module and show it on an LCD or simply receive the SMS on a mobile. All of this talk is shown through a block diagram which is shown on next page. -6- Figure 1 : System Block Diagram of Ground Station -7- 4. Chapter 4: Hardware ________________________________________________________________________  PIC 18F4620 Microcontroller  Wind Direction Sensor  Wind Speed Sensor  Rain Gauge  Temperature sensor  Pressure sensor  Humidity Sensor  Interfacing PIC 18F4620 with 4x16 LCD ________________________________________________________________________ We divided the hardware into different parts and modules so we can do it easily and properly. As some sensors are to be procured and some of them are to be made and configured so we divided our total hardware into three sections; one is anemometer 2 nd is sensors module and 3rd is rain gauge. This is also shown in figure 2 on next page. Anemometer is further divided into two sensors: one is wind direction sensor and other is wind speed sensor. These two sensors give their output in the form of pulses to be read by PIC microcontroller. Rain gauge also gives multiple pulses which are first filtered out and then given to microcontroller to be counted. Temperature sensor, pressure sensor and humidity sensor are also interfaced with PIC according to their configuration. At the end all the readings are shown on LCD. -8- Figure 2: Hardware Division 4.1 PIC 18F4620 Microcontroller Microcontroller is like the brain of whole project. All the processing is to be done by the microcontroller. We have chosen the PIC18F4620 microcontroller as main processor of our system. This is 8-bit microcontroller which possesses 40 pins. It has maximum clock frequency of 40 MHz while we have used only 20 MHz, Program memory of this microcontroller is 64k bytes and it operates on the voltage range of 4.25v. It has 4 ports A, B, C and D which possess different number of pins. -9- 4.1.1 PIC 18F4620 Pin Configuration The diagram given below shows the pin configuration of PIC 18F4620. Figure 3: Pin Configuration of PIC 18F4620 We have chosen this microcontroller because of following reasons.  It has same price as of 16F but have more computational capability so it is quiet economical  It has more flash program memory then PIC 16F  We have different sensors which are to be interfaced with different protocols like I2C, RS232 and i-wire etc. PIC 18F has all these features.  It has more analogue and digital pins.  It has one I2C port, one SPI, one UART and one USART port - 10 - 4.1.2 Specification Some of the specifications are given below. Table 1 Specification of PIC 18F46201 1 Core Processor PIC Data width 8-Bit Speed 40MHz Connectivity I²C, SPI, UART/USART Number of I/O 36 Program Memory Size 64KB Program Memory Type FLASH EEPROM Size 1 Kb RAM Size 4 Kb Voltage - Supply (Vcc/Vdd) 4.2 V ~ 5.5 V Data Converters 10 bit 13 channels A/D Oscillator Type Internal Operating Temperature -40°C ~ 85°C Package / Case 40-DIP (0.600", 15.24mm) Supplier Device Package 40-PDIP Online Catalog PIC® 18F Peripherals HLVD, POR, PWM, WDT Microchip, PIC18FXX2 Data Sheet (Microchip Technology Inc.: 2006) - 11 - 4.1.3 PIC 18F4620 Oscillator Configuration We have chosen the crystal oscillator mode of PIC 18F4620 to program the configuration register. As PIC 18F4620 has ten different oscillator modes. We have selected the 20 MHz crystal along with two 33pF capacitors. Circuit diagram of this oscillator is given below. Figure 4: Crystal Oscillator Circuit And implementation of this circuit with the pins of PIC is shown below. Figure 5: Implementation of Crystal Oscillator Exactly the same circuit shown above is implemented on hardware level. - 12 - 4.2 Wind Direction Sensor The apparatus used for the measurement of wind direction is called as Weather Vane. This device is made with a simple disk and an arrow as shown in Figure 6 below. The arrow will be aligned in the direction of wind. When air strikes at arrow at some angle it will exert some force which will rotate it. As disc is attached with the blade with the help of shaft so disc will also rotate with the same speed. Figure 6: Wind Direction Assembly 4.2.1 Grey Encoder Wind direction assembly is based on grey encoder technique. A 4 bit gray encoder is implemented which will give 16 different codes. This grey encoder is implemented with the help of Infrared transmitter receiver pair. 4 IR pairs are used which operates on 5v DC given with the help of external battery. Its working is quiet simple. When 5v is given to IR transmitter it emits IR light which can be seen through a mobile camera. When photons of this light strikes on IR receiver, then the resistance of IR receiver gets - 13 - low and it starts conducting. So now if we place a hindrance in the path of IR light then light will not reach at receiver and it will not conduct and we will get some voltage which is 0.1-2.5 v in our case and when we remove that hindrance from the path of light then receiver will get the IR rays and it will conduct so its resistance will be down which is 0.05 v in our case. So we made disc which is shown in Figure 6 given above. This disc is made such that it generates a 4-bit grey code. This is shown in figure 7 below. Figure 7: Disc of Grey Encoder 4.2.2 Code Assignment We have divided the 360 degree space into 16 parts for our own ease. Actually number of code generation 2n is dependent upon the level n so we can only have 2, 4, 8, 16, 32, 64… and so on number of codes. So if we use 5 levels, means 5 IR transmitter receiver pairs then we can generate 32 different codes which can specify 32 different directions in 360 degree of space. But in that case we left with the li erty of just 11.25 whi h means that if arrow hanges its dire tion to 11.25 then ode will e hanged. With this little liberty we cannot cater the fluctuations and jerks which will be produced by the wind and in that case arrow will keep oscillating between two directions. So implementing 5 bit grey encoder is not feasible. - 14 - So we decided to go with 4 it grey en oder whi h generates 16 different 4 it odes. With this 4 it en oder we have 22.5 of li erty for one ode whi h is quiet relia le. Now each code is specified to a particular direction as shown in below table. Table 2 Code Assignment of Grey Encoder 0000 North 0010 North of North-East 0011 North East 1011 East of North-East 1010 East 1000 East of South-East 1001 South East 1101 South of South-East 1100 South 1110 South of South-West 1111 South West 0111 West of South-West 0110 West 0100 West of North-West 0101 North West 0001 North of North-West - 15 - 4.2.3 Mechanism Illustration The whole mechanism is illustrated in figure 8 and figure 9 shown below. The disk is pivoted on a shaft and IR transmitter Receivers are placed above and below respectively. Capture plate is placed to narrow the beam width of IR light so that one transmitter’s light should not affect the other one. Shaft rotates with the help of bearings so does the dis while IR pairs and apture plate remains stati . That’s how the grey ode is generated. As shown in figure 8 one ode has 22.5 of angle. 22.5̊ Figure 8: Angle Illustration Figure 9: Mechanical Illustration 4.2.4 Circuit Simulation Circuit simulation is done on software named as MULTISIM 11.0. Circuit for one IR Transmitter Receiver pair is shown in figure 10 below. In circuit we made a switch to simulate the hindrance in the path of IR light due to presence of disk. There are three - 16 - probes in this circuit one after IR transmitter, 2nd after IR receiver and 3rd at the collector of BJT. BJT here is used as a switch. Figure 10: Multisim Circuit for one IR Pair (Not Transmitting) When S1 switch is open then transmitter U2 doesn’t transmit any light so receiver U3 doesn’t ondu t any voltage and base of Q1 has biased voltage of 700 mV. Hence due to this voltage at the base BJT conducts which gives 0 volts at the output. Figure 11: Multisim Circuit for one IR Pair (Transmitting) - 17 - When S1 switch is close then transmitter U2 transmits light so receiver U3 conduct current and base of Q1 has low voltage of 13 mV. Hence due to this low voltage at the base BJT stops conducting. This gives us 5 volts at the output. Now using this principle we made 4 similar circuits to simulate all 4 pairs on Multisim. This is shown in Figure 12 below. ON OFF ON 1 0 1 OFF 0 Figure 12: Simulations of 4 IR Pairs Above figure shows the illustration of code 1010 on Multisim on simulation level. Here 1 means output is 5V while 0 means output is 0V. 4.2.5 Hardware Development PCBs were made for circuit implementation on proteus and then fabricated with the help of PCB machine. Shaft and cylinders were some mechanical parts which are made on lathe machine in workshop. After all the making, components are soldered on PCBs. When all the PCBs were ready then they were joined along with the disc. After joining them they are tested. Figure of developed wind direction assembly is shown on next page. - 18 - IR Receivers Disc Shaft IR Transmitters Figure 13: Hardware Illustration At the end this whole assembly is fitted inside a container as shown in figure 14 to protect the inner circuits from rain and extensive climatic conditions. Arrow Output Main Wire Figure 14: Finalized Wind Direction Sensor 4.2.6 Software Development Now the signal coming from the grey encoder was to be fed to microcontroller to be programmed. As signal coming from the grey encoder was of almost 3 volts of amplitude which was not sufficient for microcontroller to read so we done some signal conditioning. We added an intermediate stage of Quad Differential Comparator LM339. This is a quad comparator which compares two signal and output 5v or 0 volts depending upon inputs. Its pin diagram is given on next page. - 19 - Figure 15: LM339 Pin Configuration This IC gave the perfect voltage levels to feed the microcontroller. 4 outputs from LM339 are given on RC1, RC2, RC3 and RC4 pin of microcontroller's Port C. 4.2.6.1 Programing of Wind Directions After the signal conditioning programing is done. We did all the programing in "C" language and to compile it we used the software "mikroC Pro for PIC". First we created 16 macros for 16 wind directions as shown below. #define east 0b10100 #define nee 0b10110 #define ne 0b00110 #define nne 0b00100 And so on… This was to make the program more generic. - 20 - Now we read only 4 bits of port c (b1, b2, b3 & b4) via bit masking, then stored in char variable "dirc" for further comparison by using this command. dirc = portc&0x1E; After getting the input at "port C" we compared it with predefined 16 directions. When input code matched to any one of 16 macros, which would be our desired wind direction as shown in the code lines below. if(dirc==east) { Lcd_Out_CP(" East "); } else if(dirc==ne) { Lcd_Out_CP(" North-East "); } So, first of all code was voltage levels are generated through electronics and then it is fed to microcontroller which then compared those levels to predefined levels to get the specific direction and then that direction is shown on LCD. 4.2.6.2 Simulation of Wind Directions Simulation is done on "Proteus 8.0" software. In Simulation connection of Microcontroller and LCD are made as per hardware. And to simulate the 4bit grey encoder we used a 4 button switch panel as shown in the figure 16 on next page. - 21 - Generation of code is simulated through positions of switches. Different configuration of switches gave different codes which simulated different directions. Figure 16: Proteus Simulation for Wind Direction 4.3 Wind Speed Sensor The instrument which measures that speed of wind is called as Anemometer. An anemometer is the assembly of equally spaced cups attached to a shaft as shown in figure 17 below. Figure 17: Anemometer Cups Arrangement - 22 - 4.3.1 Principle Air moves from the area of high pressure to the area of low pressure. The difference in air pressure is the main reason of the generation of wind. Just looking at the example of balloon, air pressure is high inside the balloon as compared to outside when the opening of balloon set loose then air rush from inside to outside creating wind. So now if we place a rotatable thing in the path of wind then with the pressure of that wind that thing will rotate. So in case of wind speed measurement we placed three rotatable cups in the path of wind which rotates with the speed proportional to speed of wind. Now a ball bearing is placed at the neck of shaft and then this shaft is attached to another shaft at which a disc is attached. Now when air strikes at the cups, cups rotate and along them the shaft also rotates. Now as shaft is attached to the second shaft so second shaft also rotates. Hence the disc attached to the second shaft rotates with the speed of cups. 4.3.2 Mechanism We are using a microcontroller for main processing. So we had to make every sensor according to the specifications of PIC 18F. In the case of wind speed measurement we had to feed the microcontroller with some number of pulses. So we made a simple arrangement in which we arranged an IR transmitter Receiver pair and a disc with holes in such configuration that when a hole in the disc and IR pair gets aligned then receiver conducts and when they are not aligned then receiver does not conduct. So we took the output at the receiver end which was in the form of pulses. This whole mechanism is illustrated in the following figure. - 23 - Figure 18: Mechanism of Wind Speed Measurement The pulses which came out of this assembly were not as perfect as there were quiet a lot of fluctuations in the level of output. So we decided to use a comparator as we used in wind direction measurement for shaping the pulses. We took the output at the receiver of IR and give it to the one inverting pin of LM339 IC and on non-inverting pin we gave 1 volt fixed voltage using voltage divider. This technique gave us well-shaped inverted pulses which have high voltage of 5V and low voltage of 0V. At the end these pulses were feed to microcontroller to be read and formula were applied. 4.3.3 Disc This instrument involves the measurement of wind with the help of electronic pulse so we made a disc which rotates with the speed of rotating cups. Disc has diameter of 75 mm and have equally spaced 16 holes in it. 75 mm Figure 19: Rotating Disc - 24 - So when this disc is placed in between the IR transmitter receiver pair then it generated the 16 pulses per revolution. 4.3.4 Circuit simulation Circuit is quiet similar to the circuit of wind direction assembly. The only difference is that we have only one IR transmitter Receiver pair in this case and switching between two levels is quiet fast. We don’t get the pure square wave in this case as we don’t have the narrow beam width of IR light so voltage keep changing from 0 to 3 volts as the disk moves. So to cater this problem we used a capacitor of very low value so when the switch is open and there is some voltage at the output the capacitor, this voltage keeps the base of BJT forward biased and output remains zero. This is shown in Figure 19 below. Figure 20: Multisim Simulation for Anemometer (No Contact between IR) Referring to figure 20 when switch S1 is open then IR is not transmitting which makes the capacitor C1 charged at 610 mv. So the capacitor makes the base of Q1 BJT forward biased so output 1 shows the 138mV which specify the voltage low. - 25 - Figure 21: Multisim Simulation for Anemometer Contacted IR) Referring to figure 21 when switch S1 is closed then IR is transmitting which makes the capacitor C1 discharged and voltage of capacitor is downed to 13.6 mV. So the capacitor makes the base of Q1 BJT not biased hence output 1 shows the 5 V which specify the voltage high. This simulation resulted into following graph. This graph shows the toggling of output in between 0 V and 5 V. Output Toggles in Between 0 & 5 Figure 22: Oscilloscope Results of Simulations - 26 - 4.3.5 Hardware Development Hardware development included both electrical circuit implementation as well as mechanical structure. These both are explained in next few paragraphs. 4.3.5.1 Electrical Hardware IR transmitter receiver circuit is implemented on PCBs. Disc containing the 16 holes also made from the PCB. After that we soldered the components on the PCB and then spindle is adjusted in between the PCBs with the help of ball bearings. As holes in the disc and holes in the PCBs for IR transmitter receiver pair are made in such way that when they are joined they are perfectly aligned with each other. Two spacers are made so that the necessary distance between the two PCB remains. This whole is illustrated in the following diagram. Spindle Spacers IR Pair Disc Figure 23: Circuit Implementation of Anemometer on PCB - 27 - 4.3.5.2 Mechanical Hardware Its mechanical parts include the rotating cups, shaft and bearing. We have already provided with the cups so we made the shaft and adjusted the bearing in it. After this we fixed the shaft with the spindle so when cups rotate then the disc should also rotate. This is illustrated in following figure 24. There are total three wires which are coming out of the Anemometer. One is brown wire which is live 5 V wire, second is black wire which is ground wire and third is blue wire which is our output of anemometer. This blue wire is then connected to the base of BJT for further circuit implementation. Figure 24: Mechanical Implementation of Anemometer 4.3.5.3 Finalized Hardware This whole hardware is then fixed inside a container to protect the circuit from the intense weather condition and rain water as this whole weather station is to be placed somewhere outside. Finalized hardware is shown in following figure. - 28 - Output Rotating Cups Shaft Figure 25: Finalized Anemometer 4.3.6 Mathematical Formulation When wind strikes at the cups it exerts the force with a tangential velocity of V. This tangential velo ity rotates the up with the angular velo ity of “ω”. Now tangential velocity and angular velocity is related as follow. V=r ω (1) Where “r” is the distan e of up from the enter, whi h is 0.2 meter in this ase. Now let's suppose "x" is the number of pulses generated by the hardware in "t" time. Now angular velocity is related with the time as follow. ω= Or, ω= Now using unitary method we can find the angle covered by the disc while generating "x" number of pulses. - 29 - Angle overed for 16 pulses= 2π Angle covered for 1 pulse= Angle covered for 1 pulse= So, Angle covered for "x" pulses= .x Hence, ω= .x (2) Where x is the pulses received by the microcontroller in time t. Now using the formula in 1, we have velocity of wind V= (0.2) × V= 0.078 × .x m.sec-1 Or V= 0.282 × Km.h-1 (3) So here wind velocity depends upon the number of pulses generated by the hardware and time taken by those pulses to be generated. 4.3.7 Software Development Software of wind speed calculation involved the timer module. This timer module was used to measure the timing of incoming pulses. Its detail is given below in next section. - 30 - 4.3.7.1 Timer-1 Module of PIC 18F4620 We used timer-1 module to count the incoming pulses of wind speed mechanism in 16 bit counting mode. In PIC18F4620, Port-C, Pin RC0/T1OSO is the pin for timer 1. T1CON is the configuration register of timer-1. This is 8 bit register to configure the timer; this is shown in figure below. Figure 26: Configuration Register of Timer-1 Bit-0 is for switching the timer on or off, Bit-1 is used to decide the clock source of timer either internal clock or external pulses as clock, Bit-2 for synchronization of external clock input while Bit-7 is used to decide whether clock register is used as 8 bit counter or 16 bit counter. In our application we have to use it as a 16 bit counter so we made bit 7, 1 and 2 high and all other low. For that we gave the T1CON value equal to "134" whose binary equivalent is- Programing of Wind Speed As shown in equation 3, wind velocity is related with number of pulses, and Time taken by those pulses, V= 0.282 × - 31 - Km.h-1 Now these pulses are fed to microcontroller's timer-1 module. As timer-1 is configured to calculate the incoming pulses, so "x" will come from the counter of timer-1 while we adjusted the timer-1 in a way that it resets after every 1 second. So first we on the timer to start the counting and then after 1 second delay we make it off and then after reading its value we reset it to count again. This is shown in code below. t1con.TMR1ON=1; delay_ms(1000); t1con.TMR1ON=0; t0l=0; t0h=0; t0l=tmr1l; t0h=tmr1h99) { rh+=1; rl=rl-100; } return; } - 40 - 4.4.4.2 Simulation of Rain Fall Mechanism Simulation of rain fall was done using a push button whish was connected to 5v DC. So when that button was pushed 1 time it gave 1 pulse and for second time it gave 2 pulses and so on just like tilting bucket for one time gave one pulse and for 2 nd time gave 2 pulses. These pulses are then fed to RB0 pin of PIC and hex file was loaded into controller and it gave the perfect output. After that it was implemented on hardware and it worked perfectly on hardware. All three sensors in working simulation are shown in next figure. Wind Speed Simulation Display Wind Direction Simulation Rain Fall Simulation Figure 33: Proteus Simulation for All three Sensors 4.5 Finalized PCB for All Three Sensors and LCD At the end all three sensors were implemented on hardware using a PCB. Comparator ICs, BJTs, PIC and LCD along with other sockets and jumpers were implemented on that PCB to make the system compact. Outputs coming from the grey encoder, wind speed mechanism and rain gauge were inserted in the PCB on specific locations and then connections were made. - 41 - PCB layout of proteus is shown below. After making the "JRBR" files this PCB was made on hardware and then circuit and coding was tested. Figure 34: Finalized PCB of Weather Station - 42 - 5. Chapter 5: Structure ________________________________________________________________________  Main Tripod  Hive for Electronic Circuitry  Base for Anemometer  Base for Rain Gauge ________________________________________________________________________ The whole weather station is a portable system which includes all the six sensors and, GSM module and power system. Main points which are taken under the considerations are  Durability  Portability  Sustainability As weather station has to be put in severe climatic conditions so it has to be durable and sustainable. So the whole structure is made with a tough material. All of the above mentioned points are explained below. 5.1 Main Tripod The whole equipment is mounted on a tripod. This tripod is made up of iron and dually wielded. This tripod is so durable that it is quiet sufficient for holding all the weight of components. This tripod is shown in figure on next page. - 43 - Figure 35: Tripod 5.2 Hive for Electronic Circuitry All the electronic components are place in a wooden hive. This hive is made in such a way that wind does not go inside the hive directly. This hive has specially made louvers as shown in figure below. Figure 36: Wooden Hive - 44 - Temperature sensor, pressure sensor and humidity sensor has to be placed inside the hive so that they are protected from direct air and rain water. 5.3 Base for Anemometer As anemometer is made inside a 5” diameter round ontainer so we made triangular base whi h has a 5” hole at its enter and pla ed the anemometer in it. This is shown in figure below. Figure 37: Base of Anemometer Fixing the anemometer inside the whole was quiet difficult job so we made small pieces of chip board and inserted in the whole along the container. After that cups were placed at the bottom and arrow was placed at the top. 5.4 Base for Rain Gauge We made a circular disk as the base of rain gauge. That disk is supported by three rods which is shown in figure 32. After this we placed the rain gauge on it and fixed the cables and pipes with cables ties. - 45 - 5.5 Finalized structure Figure below shows the complete and final structure of weather station. Rain Gauge Wind Direction Wind Speed Tripod Wooden Hive Figure 38: Finalized Structure - 46 - 6. References [1] X. Guo and Y. Song, “Design of automati weather station ased on GSM module,” in 2010 International Conference on Computer, Mechatronics, Control and Electronic Engineering, 2010, vol. 5, pp. 80–82. N. Burri, P. Von Ri ken a h, and R. 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