Temperature Dependent Speed Controller Using Thermistor Computer Science Essay

Temperature parasitic Speed ascendency Using Thermistor Computer Science evidenceThis project is a standal maven automatic sports buffer stronghold ascendency that restraints the speed of an electric fan according to our requirement. This closed eyelet feedback take in trunk is efficient and reliable by exploitation embedded technology . small dominance (AT89C51) al minors dynamic and faster control. Liquid crystal display (LCD) makes the carcass user-friendly. The sensed temperature and fan speed level apprises ar simultaneously displayed on the LCD panel. It is very compact using few components and cease be implemented for several applications including air-conditioners, water-heaters, snow meltars, ovens, heat-exchangers, mixers, furnaces, incubators, thermal baths and veterinary course tables. AT89C51 small controller is the heart of the circuit as it controls all the functions.The temperature detector thermistor senses the temperature and converts it into an electrical ( line of latitudeue) foretell, which is applied to the micro controller through ADC. The analog signal is converted into digital format by the analog to-digital convertor (ADC). The sensed and post values of the temperature ar displayed on the 162-line LCD. The micro controller drives control relays by means of ULN driver circuit to control the fan speed with the help of high gear wattage tagged wire infract resistor. Single pole dabble throw (SPDT) relays atomic number 18 connected to the micro controller through a ULN driver circuit. The relays require 12 volts at a current of around 50 mA, which squeeze outnot provided by the micro controller. So the ULN driver circuit is added. The relays are use to operate the electrical fan or for operating both other(a) electrical twist. Normally the relays carry on off. As soon as joint of the micro controller goes high, the relays operateThis project uses regulated 5V, 500mA 12V, 500mA power provide. 7805 and 7812 three terminal voltage regulators are used for voltage regulation. Bridge type full wave rectifier is used to rectify the ac out put of certifyary of 230/12V step down pat(p) transformer. This project is useful in cultivate industries for primary(prenominal)(prenominal)tenance and controlling temperature. weft OF MICROCONTROLLER there are different types of processors and controllers obtainable in the market. Industrial and control application/may require automation of the process such as temperature, pressure, liquid f pocket-sized, etc., in instal to minimize manual intervention. To automate any application an intelligent controller plays a major role. One such controller proposed for the project is AT89C51, an 8-bit microcontroller.The AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer with 4K bytes of heartbeat programmable and eradicable Read Only Memory (PEROM). The doodad is manufactured using Atmels high density nonvolatile computer storage techn ology and is compatible with the industry regular MCS-51 instruction set and pinout. The on-chip Flash allows the program memory to be reprogrammed in-organization or by a con- ventional nonvolatile memory programmer. By combining a versatile 8-bit principal(prenominal)frame computer with Flash on a monolithic chip, the Atmel AT89C51 is a powerful microcomputer which provides a highly flexible and cost strong solution to many embedded control appli- cationsThe AT89C51 provides the following standard features 4Kbytes of Flash, 128 bytes ofRAM, 32 I/O lines, twain 16-bit beatr/counters, a five transmitter two-level interruptarchitecture, a full duplex serial port, on-chip oscillator and measure circuitry.In addition,the AT89C51 is designed with static logic for operation down to zero frequency andsupports two software selectable power saving modes. The Idle Mode stops the CPUwhile allowing the RAM, eonr/counters, serial port and interrupt dodging to dwellfunctioning. The Pow er-down Mode saves the RAM contents but freezes the oscillatordisabling all other chip functions until the next hardware reset.CHOICE OF MEMORYAs the system under consideration is using AT89C51 microcontroller it has 4K Bytes of In- constitution Reprogrammable Flash Memory and EPROM for its purposes. The ATMEL AMR calculate is stored in an inbuilt flash memory. Flash memory screwingnot be reprogrammed constantly. The temperature detector device also supports the storage of last ten pairs of measurements and new measurements are over written to the older one. Hence this system is using EEPROM as a entropy storage memory. Even though EEPROM is slower than Flash memory it sens be rewritten as many number of terms as wanted.Memory OrganizationThe information presented in this chapter is collected from the Microcontroller architectural Overview, AT89C51, AT89LV51, AT89C52, AT89LV52, AT89C2051, and AT89C1051 data sheets of this book. The material has been selected and rearranged to form a quick and convenient fiber for the programmers of Atmels microcontroller family of devices. This guide pertains specifically to the AT89C51, AT89LV51, AT89C52, and AT89LV52.Memory OrganizationProgram MemoryThe AT89C Microcontroller has affiliate address spaces for program memory and data memory. The program memory can be up to 64 Kbytes long. The lower addresses may reside onchip. dactyl 1 shows a map of the AT89C51 program memory, and learn 2 shows a map of the AT89C52 program memory. The AT89C10512051 do not have off-board memory expansion. designing 1. AT89C51 Program MemoryFlash Microcontroller Memory OrganizationFigure 2. AT89C52 Program Memory0498AData MemoryThe AT89C can equivalent a shotly address up to 64 Kbytes of data memory external to the chip. The MOVX instruction accesses the external data memory. (Refer to the Instruction Set section in this chapter for a detailed interpretation of instructions). The AT89C51 has 128 bytes of on-chip RAM (256 bytes in the AT89C52) plus a number of Special assist Registers (SFRs). The lower 128 bytes of RAM can be accessed either by direct addressing (MOV data addr) or by indirect addressing (MOV Ri).CHOICE OF ADCADC0804 (Analog to Digital Converter)Figure 3 illustrates the main function of the ADC0804 i.e. to convert the remark signal from temperaturedetector device to voltage form that has 8-bit output. This device acts as a memory location or port entryto the microprocessor and does not require special logic extension.ADC0804 design.To prove that this design is according to the specifications hardware, the rule used is asfollowsADC out = Ain / Vmax X 256 (1.2)where ADC out = digital output valueAin = Input GainVmax = Maximum voltageUsing formula (1.2), it is found thatwithout amplifier, ADC out = Ain / Vmax X 256= (1/5) X 256= 51 D= 00110011 BSo that, the temperature value is = 100 / 51 = 1.96C 2CIf using amplifier, ADC out = Ain / Vmax X 256= (5 /5) X 256= 256 D= 1111 1111 B (Proved)ADC 0 804 Analog to digital converters find huge application as an intermediate device to convert the signals from analog to digital form. These digital signals are used for further processing by the digital processors. Various sensors like temperature, pressure, force etc. convert the physical characteristics into electrical signals that are analog in nature.ADC0804 is a very comm solitary(prenominal) used 8-bit analog to digital convertor.It is a single channel IC, i.e., it can take just one analog signal as input. The digital outputs vary from 0 to a maximum of 255. The step size can be alter by setting the reference voltage at pin9. When this pin is not connected, the oversight reference voltage is the operating voltage, i.e., Vcc. The step size at 5V is 19.53mV (5V/255), i.e., for either 19.53mV rise in the analog input, the output varies by 1 unit. To set a particular voltage level as the reference value, this pin is connected to half the voltage. For example, to set a reference of 4V (Vref), pin9 is connected to 2V (Vref/2), thereby reducing the step size to 15.62mV (4V/255).ADC0804 take a clock to operate. The time taken to convert the analog value to digital value is capable on this clock source. An external clock can be prone at the Clock IN pin. ADC 0804 also has an inbuilt clock which can be used in absence of external clock. A fit RC circuit is connected between the Clock IN and Clock R pins to use the internal clock.Pin DiagramAn ADC is an electronic device that converts regular signals to discrete digital numbers. The reverse operation is done by a DAC. The digital output may be using different cryptology schemes such as binary and twos compliment binary.Most ADCs are of a type known as additive which means that the range of input values that map to each output value has a linear relationship with the output value.The ADC used is an IC, ADC 0804.Features Compatible with 8080 P derivatives-no interfacing logic requisite access time 135 ns Easy interface to all microprocessors, or operates stand alone Differential analog voltage inputs Logic inputs and outputs hurt both MOS and TTL voltage level specifications Works with 2.5V (LM336) voltage reference On-chip clock generator 0V to 5V analog input voltage range with single 5V supply No zero adjust required 0.3Prime standard width 20-pin dump package 20-pin molded chip carrier or small summary package Operates ratiometrically or with 5 VDC, 2.5 VDC, or analog span adjusted voltage referenceCHOICE OF SCHEDULING ALGORITHM.Many plan algorithmic programic programic rule have been studied to guarantee the real time constraints of real time process. Scheduling decisions of this algorithm is usually based on parameters which are anticipate to be crisp. However, in many circumstances the values of these parameters are vague. The vagueness of parameters suggests us to make the usage of fuzzy logic to decide in what order the request should be executed to better utilize th e system and as a results reduce the chance of a request being missed. Our main contribution is proposing a fuzzy approach to microprocessor/microcontroller real time computer programming in which the scheduling parameters are treated as fuzzy variables. try out RATES OF CONTROLLED LOOPThe temperature measurement device Resistance Temperature Detector a measure temperature in the range of -25-150 mark Celsius. But in this application the temperature inside the container is maintained at 25 degree Celsius. There is no much deviation of temperature inside the container. The container temperature doesnt vary that much in a second. The resolution of the device is 0.1 degree Celsius if the temperature inside the container varies more than the 0.1 degree Celsius the temperature comprehend device can able to detect and the output provide be shown. Suppose the temperature inside the container is changing at the rate of 0.1 degree Celsius per second the output has the frequency of 1 Hz. So the sampling rate for the device to sample or measure the temperature neednt be that high. So the device is using a sampling rate of 1 for measuring temperature i.e. temperature measurement device is having a sampling frequency of 1 HZ. Number of bits per second will be 10 bits per second (1 HZ*10 bits) which can be easily handled by 10 bit ATMEL ADC.Temperature Sensor Resolution 0.1 degree CelsiusTemperature change inside the container 1 degree Celsius per minuteSo the frequency would be 0.6 HZ try out frequency = 0.6*5 = 3Hz (to be greater)Sampling rate = 0.3 SecondsCHOICE OF REAL TIME SCHEDULING ALGORITHMThere are basically four types of real times scheduling algorithm hertz RobinRound Robin with interruptFunction stand schedulingRTOS( Real Time Operating System)ROUND ROBINIt is the simplest algorithm. The Round Robin algorithm is characterized by the absence of interrupts. The algorithm consists of a main loop that checks each I/O device in frolic and Service them if neede d. it cannot suffer from shared data problems. Latency is limited by the maximum duration of a loop cycle. Attractive for simple environments. At the same time the disadvantage for the algorithm is it cannot set priorities. Its worst cocktail dress wait for an important caper code is the sum of execution time of all the other task code.ROUND ROBIN WITH INTERRUPTThe main advantage of Round Robin with interrupt routines deals with the very urgent needs of devices. Interrupt routines set flags to indicate the interrupt happened. Main while loop polls the status of the interrupt flags and does any follow up process required by a set flag. It moves more control over antecedence. FUNCTION QUEUE SCHEDULINGThe advantage of function queue scheduling is reaction time for high priority devices can be reduced compared to Round-Robin with Interrupts. In Round-Robin with Interrupts each loop may end up executing every go across task. Function-Queue Scheduling guarantees that at most a singl e follow-up task is executed per loop iteration. The main disadvantage is latency for low priority tasks can increase. Low priority tasks can actually starve. Queuing algorithm may be complex/costly to run/code. If a low priority follow-up task is very time consuming the latency for higher priority response times will suffer.RTOSThe advantage of RTOS is interrupts signal the need for follow-up tasks. But, unlike Function-Queue Scheduling, this is handled by the Real-Time Operating System and not by the interrupt routines manipulating flags or a queue. Instead of a loop deciding what to do next the RTOS decides. One follow-up task can be suspended by the RTOS in favouring of performing a higher priority task.-Queue. Suspension of tasks allows the worst case wait for the highest priority item to be zero. Built-in scheduling mechanism yields a system with very stable response characteristics even when changes to the code occur. Widely available for purchase.This embedded system is usin gRound Robin Schedulingas real time scheduling algorithm. The device is used to control only the temperature inside the steel container and so round robin architecture can be set here.FAILURE CONDITIONSThe system will fail only if the temperature exceeds the range of the temperature sensor.Since it is a means temperature controller the variation in the room is very slow.PERFORMANCE MEASURESAs the performance measure of system is all told dependent on PID Controller performance. So the PID controller performance can be evaluated by the periodic of the parameter hereafter against some baseline values. The performance improvement actions are taken hence on a periodic manner. So theProcess Variable fractureOvershootSteady state errorSettling time must(prenominal) be calculated by different values of PID controllersController tuning methods provide the controller parameters in the form offormula or algorithms. They ensure that the obtained control system would be stable and would mee t. These methods require trusted knowledge about the controlled process. This knowledge, which depends on the applied method, usually translates into a wobble function. The objectives which should be achieved by the application of the control system are associated with the control system features Regulating performance, Tracking performance, Robustness, noise attenuation.