University of Victoria
Contents
1. processing For example the unit of wind speed downloaded is Km hr Penman s equation requires m s If the Atmosphere is written in class a method of transforming units can be created CENG ELEC 499A Final Report Page 25 of 39 Internet Based Irrigation System Partly Cloudy 28 Jul 2006 ne Thu 27 Jul 2006 5 00 pm 20000 Partly Cloudy 5 38 00 AM 8 59 00 PM Figure 23 Screenshots of program main form Vancouver 7 Figure 24 Screenshots of program setting form CENG ELEC 499A Final Report Page 26 of 39 Penman s equation One of the most important features of this system is the ability to determine water usage To achieve this Penman s equation is utilized with the help of Dr Monahan an assistant professor in school of ocean sciences and weather This section of the report will discuss Penman s equation and its implementation The Penman s equation is used to compute the evapotranspoation rate ET and subsequently determine the duration time for the sprinkler Evapotranspiration is combination of two processes evaporation and transpiration The entire computation is implemented in software inside the PC Evaporation is the process of water transformation from liquid to water vapor and removed from the evaporating surface The Transpiration is the movement of water within the plant and the lost of water as vapor through stomata in its leaves Equation one shows the different parameters for calculati2. duration Equation 2 Penman Monteith equation Equation 3 A slope vapor pressure curve kPa Equation 4 y psychrometric constant kPa C 1 Equation 5 Bernoulli s Relation Page 4 of 39 CENG ELEC 499A Final Report Page 5 of 39 Summary The purpose of this project is to create an irrigation system that offers convenience and energy conservation The system is fully automated and utilizes water resource efficiently The system is meant to function by itself or it can adapt to traditional systems with some modifications This report describes in detail on the implementation of the proposed project discussing on how this idea can be achieved Topics include various aspects of implementation method such as software solutions hardware solutions and the Penman s equation Apart from the engineering aspect the report contains a marketing analysis section that focus on the practicality of the product discussing the systems prospect The intended reader is someone with basic knowledge in engineering who is familiar with basic operation of microcontrollers circuit theory basic internet knowledge and elementary weather knowledge CENG ELEC 499A Final Report Page 6 of 39 Introduction Traditional sprinkler systems only allow the user to setup a timer that provides irrigation at a certain period This approach has several disadvantages resulting poor water and money saving Here are several issues regards to traditional system
3. on end user s preference This task is achieved in PC using software created by Visual Basic Using pull down menus and blank fields the user has the freedom to setup desired start time and also miscellaneous information such as lawn size and crop type Overview This use case receives user s information user s location crop type pipe size garden size and display the next schedule time for the sprinkler on the user s configure display menu Event Configure System Preconditions None Post conditions Sends the user s location crop type pipe size garden size to Computer Water Usage system Display the next schedule time for the sprinkler on the user configure display menu System Configure System Actors End User Related Use Case Compute Water Usage system Typical Process Description ieee garden size pipe size te for the sprinkler 3 The configure system sends the user s information user s location crop type garden size pipe size to Compute Water Usage system 5 The next schedule time for the sprinkler are display on the user configure display menu 4 The Compute Water Usage system sends back the next schedule time for the sprinkler to Configure system Variation 1 The user s information are not entered system will return user s information are missing message Exception 1 IW user types in next sprinkler schedule time then process 3 4 will not be used CENG ELEC 499A Final Report Pag
4. that deals with the serial communication For this particular application it is only required to transmit without having to receive hence a handy custom class is built based on SerialPort Class to handle the serial communications The class is named serialPIC it has a methord named openPort which is used to initialize connection properties such as baud rate stop bits parity bit and data bits ClosPort is second method used the terminate the connection Lastly the WritePort method is called to transmit the string data The string format follows the same format described in the PIC software design section Once the Update Information button is clicked or timed out the location along with current time start time and end time will be formatted into a correct string format and eventually sends through the serial port Display the weather information The weather parameters downloaded from Yahoo Weather contains the following information Location Atmosphere Astronomy Condition Wind Units and Forecast Each kind of information comes with a sub category of detailed data For example Atmosphere contains humidity pressure visibility and rising To organize this data structure a class named Atmosphere with properties of humidity pressure visibility and rising is created Similar classes are generated by the same token The reason to use class instead of structure is so that the program capacity can grow for the further data
5. C 1 P atmospheric pressure kpa Alatent heat of vaporization 2 45 MJ kg 1 Cp specific heat at constant pressure 1 013 10 MJ kg C 1 Ration molecular weight of water vapor dry air 0 622 CENG ELEC 499A Final Report Page 28 of 39 climate grass ET Ge reference SAY oe Radiation a Temperature Wind speed Humidity well watered grass Figure 25 Evapotranspiration Process Figure 29 show the transportation process where the evaporation process takes in account of temperature humility solar radiation and wind speed The transpiration process takes in account of the movement of water within the plant and the lost of water as vapor through stomata in its leaves Ko factor ET x well watered crop optimal agronomic conditions Figure 26 Evapotranspiration process with co factor Figure 30 shows the Evapotranspiration process with co factor Kc where Kc stands for different types of the crop Implementation The calculation for evaporation rate is carried out in the PC with software using floating point variables Small functions are created to calculate parameters such as slope vapor pressure and y psychrometric constant A main function that represents the entire Penman Monteith equation is created to calculate the final result Any constants associate with the computation is initiated globally Variables such as temperature and pressure are linked to the function that acquires weather data CENG EL
6. C DIV 1 enable interrupts INT TIMERQ enable interrupts GLOBAL Figure 11 PIC Timer Operation To keep in track of important data for this project the PIC must have the following database listed below This database is updated whenever the PC sends a stream of new data through the serial port e Location City Province State Country e Date Month Date Year e Current time Hour Minute Second e Start time Hour Minute e End time Hour Minute To check for receive data PIC calls function if kbhit If there are new data in the receive buffer the PIC will go ahead and process it CENG ELEC 499A Final Report Page 18 of 39 fuse ese paud S600 smit PIN C6 coy PIN Cti parity N bats LE kb gets strRevd Figure 12 RS232 Operation In terms of the received data everything is in string format The reason is because it is much simpler to display the string directly on to LCD The received string vector is in the following format EE Ee Ee ee EE ee ee ee 3 n C O u V e r 20 20 20 20 20 B C 20 18 19 20 21 22 23 2425 26 i27 28 29 30 31 32 33 A N J U L 2 2 1 20 2 0 0 6 20 Hi Hi 135 36 37 38 39 40 41 42 43 dB 47 48 49 50 1 M1 S1 Si 7 H2 H2 M2 M2 2 H3 H3 M M Si Figure 13 PIC Vector Format ZRORK lt S Where the number denotes the index of the vector and 20 denotes a space Since the entire data is received in string format some of the data such a
7. EC 499A Final Report Page 29 of 39 Bernoulli s equation This section of the report covers briefly on how basic thermodynamics namely Bernoulli s equation can help us to calculate water flow This analysis is crucial when determining how much water should the system use in terms of sprinkler size nozzle area and water pressure With the help of Dr Henning Struchtrup from the Mechanical Engineering department the following analysis is deduced Typical household have water pressure to be about 40 50psi It is safe to assume on average is 45 psi The water pressure depends on the location of the house itself The following is Bernoulli s equation P P 1 Vf MI AV 4V p p 2 Equation 5 Bernoulli s Relation Where P1 and P2 is pressure inside and outside the pipe respectively p is water density kg m V is the speed of water exiting the pipe m s A is the area of the nozzle or pipe cross section cm The normal pressure is 1 atm 14 6956 psi or 1 psi 0 06805 atm Please refer to the following diagram for depiction Al pipe diameter A2 nozzle diameter P1 45 Psi P2 1 atm or 14 7 Psi el Pipe Nozzle Figure 27 Basic Thermodynamics Using the provided equation the system can calculate water exit speed once the user provides the nozzle area Water volume m Nozzle area m x Water exit speed m s x Time duration s The following is a lookup tables that will give a comparison between w
8. Schedule Start_time End_ time TurnOn TurnOff ManOn Mamm TurnOn Figure 8 Irrigation Sequence CENG ELEC 499A Final Report Page 16 of 39 PIC Microcontroller software design This section of the report describes the software design embedded inside the PIC backed by a flow chart To program the PIC a PIC burner is required In this project MPLAB s ICD2 with C compiler is used Traditionally PIC code is written in Assembly language C compiler allows us to program the PIC using C language which proves to be a major advantage Since C is a high level language it has a rich library of built in functions This feature makes programming easier since we dont have to worry about initializing any registers Figure 9 MPLAB ICD2 PIC Burner To design the program embedded inside the PIC the first step is to list all the tasks that the PIC is required to perform In our project the PIC is required to attend these major tasks e PIC must loops forever e PIC will poll the status of the I O ports reading inputs for AUTO or MANUAL mode e PIC checks the timer at one point If the current matches with start time the PIC turns on the sprinkler If the current time matches with end time the PIC turns off the sprinkler e PIC checks for received data If new data is received it will automatically update its data base with the new value e PIC writes the newest
9. Title Date From To University of Victoria Department of Electrical and Computer Engineering ELEC CENG 499A Design Project Final Report Internet Based Water Saving System July 28 2006 Eric Yang 0331697 elyyang uvic ca Wei Zheng 0423717 weizheng uvic ca Alan Lin allin uvic ca Dr M Sima project supervisor CENG ELEC 499A Final Report Page 2 of 39 Acknowledgement We would like to thank the following for making this project possible Project supervisor Dr Sima for his assistance and advice throughout the project UVic School of Earth and Ocean Science assistant professor Dr Adam Monahan for his assistance in our understanding in weather and climate UVic Department of Mechanical Engineering assistant professor Dr Henning Struchtrup for his assistance in our understanding in Bernoullis equation for calculating water pressure UVic Music Information Sound Technology Interdisciplinary Center PhD student Ajay Kapur for providing us with the MPLAB ICD2 PIC programmer CENG ELEC 499A Final Report Table of contents Acknowledgement Table of contents Table of figures and equations Summary Introduction Project challenges Overall design description Overall design solution Overall system description PIC Microcontroller software design Hardware design PC software design Penman s equation Bernoulli s equation Marketing analysis Conclusion Discussion and Recommendation References A
10. art for obtain weather parameters Retrieve and parsing XML data from Yahoo weather website Display weather information on Sorea Write weather information to bog file for further usage Use Penman Equation to calculate watering duration Contnbute serial data for transmitting to microconler
11. at are required to do the following tasks Configuration Obtain weather parameters Compute water usage display status and Irrigation The use case diagram shows an overall association of the five major components Configuration Obtain weather parameters and compute water usage are achieved using PC while display status and irrigation are achieved in the PIC USE Case Internet Based Water Saving System e lt lt Actor gt gt Get Weather Weather Configure System Parameters Website Information User e Compute Water Usage lt lt Actor gt LCD lt lt Actor gt gt Timer Display Status lt lt Actor gt gt Lee spinkler Irrigation S LED Figure 3 Use Case The actors associated are weather website LCD sprinkler and the timer In this system the user has access to system configuration and the freedom to choose between manual irrigation and auto Irrigation The system will obtain weather parameters off weather websites The computation of water usage is based on configuration the weather parameters and the timer the system will update a new value every time period The system will display the current status using the LCD Using the timer irrigation process is carried out based on the computed values to turn on the sprinkler in which our system uses a LED as an indication CENG ELEC 499A Final Report Page 11 of 39 Configure System Configure system shows how the system is setup based
12. ater usage and related parameters This look up table is implemented in the system to determine water usage based on the given parameters CENG ELEC 499A Final Report Page 30 of 39 Constants Calculated Water Pressure 45 psi Water speed 8 mis Atmospjereic Pressure 1 atm Atmospjereic Pressure 14 7 psi Water Density 1 kg m Nozzle Diameter Nozzle Area Water Usage cm m m m3 s 1 0 01 7 85398E 05 0 000628319 1 25 0 0125 0 000122718 0 000981748 1 5 0 015 0 000176715 0 001413717 1 75 0 0175 0 000240528 0 001924226 2 0 02 0 000314159 0 002513274 2 25 0 0225 0 000397608 0 003180863 25 0 025 0 000490874 0 003926991 2 15 0 0275 0 000593957 0 004751659 3 0 03 0 000706858 0 005654867 3 25 0 0325 0 000829577 0 006636614 3 5 0 035 0 000962113 0 007696902 3 75 0 0375 0 001104466 0 008835729 4 0 04 0 001256637 0 010053096 4 25 0 0425 0 001418625 0 011349003 4 5 0 045 0 001590431 0 01272345 4 75 0 0475 0 001772055 0 014176437 5 0 05 0 001963495 0 015707963 Figure 28 Water usage look up table CENG ELEC 499A Final Report Page 31 of 39 Marketing analysis The main focus of the proposed project is to design a system that is for practical use In this section of the report practicality of the system will be briefly discussed for marketing purposes Let s not forget the main focus of the project is to come up with a low cost water efficient solution to replace or adapts to traditional irrigation system Here are some of the advantages the sys
13. chive com Available URL hittp Awww datasheetarchive com DLP Design DLP USB232M USB Adapter online datasheet 2006 DLP Design Available URL hittp Awww dlpdesign com usb usb232 shtml Wikipedia PIC microcontroller online encyclopedia Available URL http en wikipedia org wiki PIC microcontroller Wikipedia Penman equation online encyclopedia Available URL http en wikipedia org wiki Penman_ equation Carl E Anderson Penman Equation for Potential Evaporation online power point presentation Available URL http Awww abe iastate edu AE520 Penman ppt FAO Corporate Document Repository Crop evapotranspiration guidelines for computing crop water requirements online document database FAO 1998 Available URL http Awww fao org docrep X0490E x0490e06 htm Aerodynamcs of Bicycles Bernoulli s Equation online document Available URL http Awww princeton edu asmits Bicycle_web Bernoulli html Dr Adam Monahan Assistant professor University of Victoria School of Earth and Ocean Sciences Available URL http web uvic ca monahana monahan html Dr Henning Struchtrup Assistant professor University of Victoria Department of Mechanical Engineering Available URL http Awww me uvic ca Faculty HSres html Page 35 of 39 CENG ELEC 499A Final Report Appendix IC t schemati ircui C 50 R a Slk E s t Ai S 5 LA GM SH oF Wi 23 4 ID 4 i lt
14. e 12 of 39 The sequence diagrams depict the configuration sequence from start to finish in chronological order Menu i Set_Value water_value Set_System i Water_Value location crop pipe garden Water Time start_time end_time Display Water_time SysStatus Location SrpinkStatus Figure 4 Configure System Sequence Compute Water Usage This process is done in the PC using software Once all the desired information is present the software will compute the water usage using Penman s equation For more detailed information on this process please refer to PC Software design section This process is being called upon every period determined by the timer The user can setup this period through configuring systems The computed result is displayed on LCD and carried out by irrigation process Overview To determine the next schedule time for the sprinkler Event This use case receives a request from the timer and then determines the next schedule time for the sprinkler Preconditions End user has already type in all the require data in Configure System Post conditions Sends the next sprinkler schedule time to display status system Sends the next sprinkler schedule time to irrigation system System Compute Water Usage Actors Timer Related Use Case Configure System Get Weather Parameter Display Status Irrigation CENG ELEC 499A Final Report Page 13 of 39 Typical Process Description 1 Ti
15. e Traditional system operates independently of actual weather status A classic scenario would be the sprinkler watering the garden during an unexpected summer storm subsequently over hydrating the plants e Traditional system requires human intervention The user is required to determine the duration of the watering process e Traditional system requires sensors to improve accuracy Sensor implementation and maintenance cost extra dollars As personal computers and internet usage becomes more and more popular the inspiration is to make use of readily available resources such as weather data off weather websites and set up the watering operation accordingly The exact computation will be based on a model namely the Penman equation The model will require several parameters from both the internet and from users input based on a selected city profile The weather data will be acquired from weather websites such as http www theweathernetwork com or http weather yahoo com Given that most websites updates their information frequently the system has the advantage of obtaining newest information at all times allowing it to cope with sudden weather changes The system also has the flexibility of global operation since most websites contains a database of major cities in the world This idea has several advantages such as the ability to determine the amount of water to be used along with the avoidance to setup any sensors In addition it is ful
16. e its low cost and re programmable feature PIC utilizes EEPROM which can be erased electronically with the appropriate apparatus PIC model 18F2320 is chosen merely because its low power features capable of serial data transfer and I O operations It has 8K bytes of memory which is sufficient for our task In addition our design team is familiar with this model plus microchip offers free samples The motive of a LCD display is for users to monitor the status of the PIC independently of the PC With small in size and lower power consumption the LCD display has the flexibility to be setup in different areas In addition the LCD display offers the benefit when comes to debugging the PIC during development HITACHI LM044L LCD display is readily available from one of the team members hence it was used It has 20 characters by 4 lines with a total of 80 characters sufficient to display all the data required plus Its 98 x 60 mm dimension is a reasonable size Lastly switches and LED are implemented for monitoring purposes Moreover it gives the system the flexibility of selecting different modes of operation It also has the benefit when it comes to de bugging purposes CENG ELEC 499A Final Report Page 10 of 39 Overall system description This section of the report describes the entire design in a system aspect UML Use Case diagrams and UML Sequence diagram are presented to depict the idea The entire system consists of 5 major components th
17. erface converts the data into RS 232 format which is subsequently fed into the microcontroller Microchip Technology s PIC is a programmable RISC microcontroller that will control any hardware devices associated with the system It keeps track of all the data sent from the PC The idea to have a microprocessor is so that the entire system doesn t have to rely completely on PC s control If the system were to depend on the PC at all times it would be utterly useless shall the user decide to shutdown their computer For simplicity sake the microcontroller will be referred as PIC from now on Based on the computed outcome the PIC will carry out the irrigation operation accordingly The amount of water being irrigated simply depends on the duration of the watering process CENG ELEC 499A Final Report Page 8 of 39 To control the water flow a 2 position valve also known as a digital valve will be used A 2 position valve is normally closed when there is a presence of a DC voltage input the valves open fully allowing the water to flow through This valve can be installed in a continuously flowing water source For this project the signal that drives the sprinkler terminates with a LED as indication Due to budget concerns a 2 position valve is not implemented in the prototype Figure 2b Complete Prototype with PC CENG ELEC 499A Final Report Page 9 of 39 Overall design solution This section of the report describes the entire sys
18. interface PIC Setup Apart from the standard Vcc and Vee for powering the PIC it requires a crystal oscillator that functions as a clock In our system a 10 MHz oscillator is used with two 10pf coupling capacitors In order for the PIC to function pin 1 MCLR must be connected low When MCLR is set high the PIC resets the embedded program In our system we implemented a reset feature using a push button connected to MCLR Figure 18 Microchip PIC Microcontroller LCD display setup The display requires only 4 inputs for parallel data transfer into port B of the PIC The PIC has built in function that utilizes lower nibble to control the LCD display and upper nibble to send in the data This allow the LCD to be controlled entirely by an 8 bit port as opposed to using entire port for 8 bit parallel data transfer with a second port for controlling signal Extra features include a contrast adjust by implementing a trim pot connected to pin Vo Figure 19 Hitachi LM044L mounted USB RS 232 interface setup The USB interface offers two types of powering method Internal self power and external bus power In this system external bus power is chosen because the PIC needs to function independently of PC connection status More importantly if there is a short on the circuit board power out pin of the USB will not be affected This will prevent the USB from drawing too much current subsequently damage the PC CENG ELEC 499A Final Re
19. ly automated meaning it requires minimal user operation Project challenges Before the actual implementation of the proposed project the following challenges are anticipated Establish communication between software and Hardware PIC Establish a protocol for data transmission between various components Establish an accurate timer inside the PIC Establish an accurate model that determines amount of water to be used Establish the ability to download data off the internet and form a database Establish the ability to work autonomously in the absence of internet CENG ELEC 499A Final Report Page 7 of 39 Overall design description This section of the report describes the entire design step by step with emphasis on the functionality for each component in a hardware aspect Please refer to the diagram for a depiction of the entire system Personal Computer lw USB Serial Interface Sprinkler LCD Display City Victoria BC July 2ist 06 5 30 PH Auto Time 50 mins Figure 1 Overall System Description Initially the user downloads the weather data via the internet with the provided software program Combining the data set by the user and the downloaded parameters the result are being calculated using Penman s equation The outcome is the duration of how long the sprinkler will operate The software program will transmit all the necessary information through the USB serial port interface The int
20. mer sends a request to Compute Water Usage to determine the next schedule time for the sprinkler 2 Compute Water Usage received a request from Timer to determine the next schedule time for the sprinkler 3 Bases on the end user s location the Compute Water Usage send a request to Get Weather Parameter 4 The Get Weather Parameter sends the weather information to Compute Water Usage 5 The Compute Water Usage sends the weather information to the Penman Monteith equation 6 The Penman Monteith equation sends back the evapotranspiration rate to Compute Water Usage 7 The Compute Water Usage checks the evapotranspiration rate and determines the next schedule time for the sprinkler 8 The compute Water Usage sends the next schedule time to Irrigation system to turn on off the sprinkler 9 The compute Water Usage sends the next schedule time to Display Status system Variation 1 The weather parameter does not found from the weather website system will return weather information not found message Exception 1 None The following diagram shows the sequence for computing water usage CENG ELEC 499A Final Report Page 14 of 39 Timer Determine Watering Get Weather Information Penman Montcith Equation er Crop l GetWeatherInfo onehour mm mm me Req WeatherInfo WeatherInfo Send WeatherInfo l Evapotranspiration i ee ee pe vg K Se eS SS See i WaterSchedule star
21. ng the reference evapotranspiration 900 O408AlR G aa lle ze E Acel 0 291 ET reference evapotranspiration mm day Ki net radiation at the crop surface M mr day G soil heat flux density M m day 1 T alr temperature at 2 m height C U wind speed at 2 m height m se e saturation vapour pressure kPa e actual vapour pressure kPa E E saturation vapour pressure deficit kPa A slope vapour pressure curve kPa t01 e psychrametric constant kPa CT Equation 2 Penman Monteith equation The Evaporation Process Energy is required to change the water state from liquid to vapor The solar radiation and the temperature Equation 1 T provide the necessary energy for the water to transform from one state to another The energy that is required to remove water vapor from evaporating surface is the difference between the water vapor pressure at the evaporating surface Equation 1 es and the surrounding atmosphere Equation 1 ea As the evaporation process continues the surrounding air slowly become saturated and eventually process stop once the wet air is not transferred to the atmosphere The wind speed Equation 1 u2 is one of the key factors to replace the saturated air with the drier CENG ELEC 499A Final Report Page 27 of 39 air Therefore the solar radiation temperature humidity and wind speed are the essential parameters for determine the evaporation The evaporating surface incl
22. port Page 21 of 39 Figure 20 DLP Design USB RS232 interface A 5 volt regulator with diode protection is used to provide power for the entire circuit The initiative is to mimic the product to be powered by a 9 volt battery in the future If the user somehow mistaken the polarity the diode will come in play saving the system To indicate if USB is connected to the PC we used a LED on the USB self power out pin subsequently connected into pin 2 of port B Initially if the USB is disconnected the PIC cannot determine pin 2 s logic status therefore a resistor must be connected in parallel to the LED Lastly all switches and LED must have a current limiting resistor in series The purpose is to limit the current that might drain inside the PIC once everything is powered off and also to protect the LED from burning out after drawing too much current Please refer to the attached circuit schematic attached in the appendix CENG ELEC 499A Final Report Page 22 of 39 PC Software design This section of the report describes the PC software design in detail backed by flow charts The PC software consists of four major tasks 1 Obtain weather parameters from internet 2 Calculate irrigate duration 4 Communicate with microcontroller 5 Display weather information Obtain weather parameters from the Internet a Reasons to use xml to retrieve weather information XML stands for Extensible Markup Language It is a makeup language used
23. ppendix Circuit schematic Appendix PIC Software Flowchart Appendix PC Software flowchart for serial data transmit Appendix PC Software flowchart for main program Appendix PC Software flowchart for obtain weather parameters Page 3 of 39 10 16 20 22 26 29 31 32 33 34 35 36 3 38 39 CENG ELEC 499A Final Report Table of figures and equations Figure 1 Overall System Description Figure 2a Complete prototype Figure 2b Complete prototype with PC Figure 3 Use case UML Figure 4 Configure system sequence Figure 5 Compute water usage sequence Figure 6 Obtain weather parameter sequence Figure 7 Display status sequence Figure 8 Irrigation sequence Figure 9 MPLAB ICD2 PIC Burner Figure 10 PIC IO Operation Figure 11 PIC Timer Operation Figure 12 RS232 Operation Figure 13 PIC Vector Format Figure 14 PIC Char to Integer Conversion Figure 15 LCD Operation Figure 16 PIC LCD Display Format Figure 17 LCD Display Figure 18 Microchip PIC Microcontroller Figure 19 Hitachi LM044L mounted Figure 20 DLP Design USB RS232 interface Figure 21 Load XML Data from Internet Figure 22 Parsing XML Document Figure 23 Screenshots of program main form Figure 24 Screenshots of program setting form Figure 25 Evapotranspiration Process Figure 26 Evapotranspiration process with co factor Figure 27 Basic Thermodynamics Figure 28 Water usage look up table Equation 1 Irrigation
24. r ilk E L e f v TAV D NA Power LED A Su 94 RBO ANIZ R RBL ANIB Ik RAB ANB RB2 ANB RE AN9 Epi ep Si RE47AN11 RA2vANe RASAN S Raa TeckI _RB KBI3 Rce T1OSO RASANA RCI TIOSI L OSC1 CLKI RC2 CCP1 l OSC2 CLKD GER F A Su BEAT BC Schw R 1k ih VSS VSS a Dr PE LCD LM44 L Display 18K USE Current Limiting LCD Brightness Adjust USB Serial Interface Ld ee wo Internet Based Water Saving System Hardware Schematic ELEC CENG 499 ae 2 Fa S Ge O are1972006 CENG ELEC 499A Final Report Page 36 of 39 PIC Software Flowchart Initialize Poll status for UC Turn on off the Schedule time mon sprinkler New Data Recived Update new data Display LCD CENG ELEC 499A Final Report Page 37 of 39 PC Software flowchart for serial data transmit Transmit string data in a correct format Glose com port CENG ELEC 499A Final Report Page 38 of 39 PC Software flowchart for main program Selup Graphic User Interface Read setting rom windows User click on Obtain Weather Info Button Jser click on Update S Information Button Timer time out Transmit serial Gets weather data to information microcontroller from internet Gets weather information from internet Transmit serial data to microcontroller CENG ELEC 499A Final Report Page 39 of 39 PC Software flowch
25. r pipe and the speed of the water from the sprinkler is applied to calculate the duration of the irrigation time see Bernoulli s equation section The user is given a choice of setting a Start time the end time is simply the calculated duration added on top of start time The following formulas are used calculate irrigate duration Vol ET eA geen 2 m S Cy Equation 1 Irrigation duration Where Vol Volume of water evaporated ETc Evaporation Rate A Garden Area square meters S Water Speed m s D Sprinkler Diameter cm Dur Irrigate Duration mins CENG ELEC 499A Final Report Page 24 of 39 The user is given the freedom to set the number of sprinkler diameter of water pipe and the speed of the water When the information is saved the value display on the setting form will be assigned to global variable and saved in registry for the further usage Floating point variables are used since most are in floating point and the motive is to maintain a certain degree of accuracy Helper functions are created to convert units for example from Square feet to Square meters Any constants associate with the computation is initiated globally Variables such as garden area and sprinkler diameter are linked to the function that acquires configuration data Transmit data to microcontroller From the software s perspective it needs to communicate with the hardware via serial port Visual Basic NET has a SerialPort Class
26. represents the fundamental building block of XML documents It is an implementation of the tree model established by the W3C Document Object Model XMLNode supplies a series of derived classes including the XMLDocument class CENG ELEC 499A Final Report Page 23 of 39 In the screenshot a xmIDocument object is created and the XMLNode is to retrieve the data from the XML document define the xmlDocument Object Tim moc AS AmLDocument Hothing Create the XML Document mloc Hew XmLDocument LU Load the Xml file mloc Load xml URL Figure 21 Load XML Data from Internet Dim mode As AmLHode Nothing gets the Atmosphere data mode mDoc SelectSingleHode rss channel yweather atmosphere Get the location Attribute Value With objAtmosphere humidity mHode Attributes GetHamed tem humidity J Value pressure mode Attributes GetNamed teml pressure Value rising mode Attributes GetNamedl tem rising Value visibility mode Attributes GetHamed teml visibility J Value End With w hsmanager Figure 22 Parsing XML Document Calculate irrigation duration Water evaporation rate is calculated using Penman equation see Penman Equation section The unit of the final result is mm day and is later converted to conventional volume unit Once the volume of water evaporate is known the system takes in account of compensation for evaporation The number of sprinkler diameter of the wate
27. s current time scheduled time and end time are to be converted into integer format The reason is because the timer variables are all in integer format in order to do any computation or time comparison we employ the following method to convert ASCII value to integer value fensec gecg 1 48 onesec secs 1l0 46 Figure 14 PIC Char to Integer Conversion The final task for the PIC is to display any necessary information on the LCD The C Compiler has built in LCD display functions that make life easier Ted dere E Led PUES Ey led_gotoxy 3 4 Lok DE EE CR un HL Figure 15 LCD Operation In this project the data displayed on LCD includes the following e Location City Province State Country e Date Month Date Year e Current time Hour Minute Second e Start time Hour Minute e End time Hour Minute e Mode Auto or Manual e USB status Connected or Disconnected e Sprinkler status On or Off CENG ELEC 499A Final Report Page 19 of 39 The LCD display is capable of displaying 20 characters by 4 lines Here is the LCD display format used by the system l MM PEPPI 19 20 V i c a E ES 7 3 S EE Figure 17 LCD Display CENG ELEC 499A Final Report Page 20 of 39 Hardware design This section of the report describes the hardware design of the system The hardware system for this project is fairly simple the circuitry consists of 3 major components PIC LCD and the USB
28. t_time end time l i i l i l i l i l i l i l i l i l i l i l j Figure 5 Compute Water Usage Sequence Obtaining weather parameters This process is achieved in PC using Visual Basic net It has the ability to download XML data based on a given URL The below sequence shows how the system downloads data from the weather website once the trigger is activated the system will obtain the newest information from the weather website The trigger is set on a timed basis or the user can manually select when to download the data Determine Watering Get Weather Information Weather Website l Req WeatherInfo Req WeatherInfo Return Weatherinfo Return Weatherinfo SS ee ee Figure 6 Obtain Weather Parameters Sequence CENG ELEC 499A Final Report Page 15 of 39 Display status This process is achieved in the PIC Once the system is setup the status of start time end time and other information such as date and location are shown on the LCD For exact details please refer to PIC software design section Display Status LCD Display Water_time SysStatus Location SprinkStatus Display Water_time Sysotatus Location SprinkStatus Figure 7 Display Status Sequence Irrigation This process is also achieved in the PIC The PIC will turn on the sprinkler based on the computed time or by user s manual control Please refer to PIC software design section Water
29. tem design by discussing the purpose for each component in other words why we choose to have these components in the system The primary reason for a personal computer to be included in the system is because PC allows a higher level of software program with friendly user interface It also has the plus side of sufficient memory resources and better capability of handling complicated tasks such as Penman s equation If the decision is made to implement any complicated tasks in the microcontroller we risk running out of memory A second reason is that PC is a readily available gateway to the internet It is safe to assume most people nowadays have a PC at home with internet access The initial proposal to have a microcontroller with internet access capability is not desirable due high in cost and limitation to wired access The purpose of an USB to serial interface is that USB technology is widely used in most computers USB have surpassed traditional COM ports by speed and plug and play feature Most new computers do not have the traditional com ports available Since the PIC is designed to recognize serial data the interface will serve as a virtual serial port under windows operating system allowing the data to transfer in RS 232 format Utilizing the FTDI chip that converts legacy peripherals to USB DLP design s USB232M G USB to SERIAL UART interface module is ideal for this application The idea of choosing Microchip s PIC is becaus
30. tem offer Since we are using weather data that is readily available online for free the cost is lowered by preventing to install sensors in the home owner s backyard If the sensor shall malfunction it takes time to repair as an opposed of our system only requires a software update The system is flexible since the software contains a vast database for different types of crops to different regions of the world The system can be used in most metropolitan area providing it has internet access The system itself is not meant to replace existing sprinklers but more of an add on to enhance the traditional system This will save potential investor money by keeping their old system CENG ELEC 499A Final Report Page 32 of 39 Conclusion To summarize all the proposed solutions were implemented in this project A functional prototype was developed by the deadline In theory this system should provide an energy saving alternative to the traditional sprinkler systems however due to time limitation the accuracy of the result can not be verified Although there isn t sufficient evidence on how the system will perform on a long term basis for the time being the system seems to comply with the proposed specification After numerous test cases it showed an indication that the system does allow more water to run on a hotter day and completely shuts off on a rainy day The marketing analysis stated several advantages this system offers The fut
31. to describe the data The advantages of XML are the following XML describes the data instead of displaying it By using the XML the data can be separated from the text displayed on the web browser The data is more organized in this fashion XML is a cross platform language It will always work with different types of servers such as My SQL Server or Microsoft SQL 2005 Server b Reasons to choose Yahoo Weather There are numbers of website available Some of them do not provide data in XML format but rather in HTML format A string search has to perform to obtain the weather data in HTML format The disadvantage of the string search is that it is hard to implement when the data is organized in HTML table format Some of the websites have limited number of the cities Take for example the proposed www weather com Our project goal is to design a system that is adaptable to in any region of the world Yahoo Weather website provides the data not only in HTML format but also in XML format which give us the flexibility to implement our solution c Implementation Visual Basic NET includes a name place that allows the program to obtain parse and manipulate XML data it s under System nameplace The XmlDocument class implies the ability to load a XML file The class implements the DOM which is an in memory cache tree representation of a XML document which allows the user to navigate and edit the document The XMLNode class
32. udes two factors that effects the evaporating process the soil surface equation 1 Rn which will be entered by the user and the amount of water are at the evaporating surface which will be frequent rains and irrigation Transpiration Process Transpiration is the process of water movement within the plant tissues and the vapor removal to the atmosphere Crops lost majority of their water through the stomata the small opening on the crop which allows the gases and water vapor pass through There are only minority of the water are used within the crop Although there are many different factors to determine the transpiration rate the temperature radiation humidity and the wind speed However the biggest factor to determine the transpiration rate is the soil water content and the ability of the soil to conduct water to the roots Equation 1 G Calculation for A slope vapor pressure kPa C mt The slope of the relationship between saturation vapor pressure and temperature slope vapor pressure kPa C 1 is required for calculating the evapotranspiration 4094 0 6108exp A ERR A 2 T 237 3 Equation 3 A slope vapor pressure curve kPa Where A slope of saturation vapor pressure curve at air temperature T kPa C T air temperature C Calculation for y psychrometric constant kPa C 1 aie 3 y 0 665x10 F EM Equation A y psychrometric constant kPa C Where y psychrometric constant kPa
33. ure remains bright for the project shall we decide to pursuit the project to a further level This project is deemed successful since all the objectives are met CENG ELEC 499A Final Report Page 33 of 39 Discussion and Recommendation The primary weakness of the system is the timer function inside the PIC generated by interrupts is not accurate The 24 hr clock will be off by few seconds per day To compensate this weakness the value of the timer is constantly updated by the PC as long there is connection This weakness is not a major issue since 1 second won t have much effect on water conservation The second weakness of the design is that weather websites does not covers all regions in the world Weather websites are typically associated with major cities and metropolitan areas thus this limits the coverage area of our system Overall we haven t discovered any major problems that would hinder future development for this system Improvements that are feasible in the future include to establishing a wider range of database to allow more flexibility and wireless connections between USB and PC to maximize the operating range and convenience CENG ELEC 499A Final Report Page 34 of 39 References Microchip PIC18F2320 Data Sheet online datasheet 2003 Microchip Technology Inc Available URL hittp Aww1 microchip com downloads en DeviceDoc 39599c pdf Datasheet Archive HITACHI LM440L online datasheet 2006 DatasheetAr
34. value to the LCD display with the newest information The polling of I O to check for switch status is relatively easy C compiler allows individual pins be checked using input X function Prior to using the I O PIC must initialize I O setup by calling use fast_io A with A being the port name The direction of the I O ports can be set by calling set Ire at CENG ELEC 499A Final Report Page 17 of 39 fuse fast 10 A set EE cat URRUTI if input PIN Al d led gotoxy 18 4 output high PIN A3 Figure 10 PIC IO Operation To setup the timer an interrupt must be generated whenever the 16 bit system clock overflows Each time the counter overflows at the crystal s frequency an integer variable should be incremented To generate 1 second the calculation must be computed so that number of the integer incremented multiplies the time for increment is equal to 1 second The value for the 16 bit system clock can be changed using set_timer command however in this project it was only called once to reset the value when program is being initiated The setup_timer function changes the clock s divisible function and determine which clock to use Once the setup is completed the system must enable all interrupts by calling enable_interrupts function int counter define COUNTS PER SECOND 124 Hint eter void clock isr if torus Wi segs Okay counter COUNTS PER SECOND J i set Erneta setup timer RTOC INTERNAL RTC
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