Automatic Temperature Control System
Contents
1. control state O j delay ms 50 wait 50ms before next loop start button_loop increment button_loop for next loop number 5 222. In the photograph below the microcontroller device on the bottom is connected to a breadboard circuit that controls the fan speed depending on the status of the motion detector and temperature sensor To implement this project we segmented the project into terms of software and hardware First we devised a schematic diagram that would control a fan to operate at 3 different speeds The speed would be controlled by the microcontroller by sending out a 5V signal through a network of transistors which would result at turning on a fan at a particular speed By the end of the project our group had implemented many topics that we learned throughout the semester By using transistor theory circuit analysis and software programming we were able to implement a microcontroller based automatic temperature control system Introduction The purpose of this project is to demonstrate how microcontrollers can be used and applied in a real world application One practical use is to incorporate a microcontroller in a temperature control system that can be used for automatically controlling a rooms temperature By using a system of sensors and actuators a microcontroller can act as an active device that responds to various inputs by sending control signals to other branches of a circuit that controls their corresponding actuators The microcontroller our group decided to use was an Atmega 128 based microcontroller that was programmed with an
3. Polarized parts put in the wrong way Transistor pin out varies so check the pin out of the devices you get Electrolytic caps often look like a short if the voltage is reversed Bad parts even when we confirmed that our circuit was wired up correctly we were able to narrow our problem down to a bad part A defective motion sensor will not allow the rest of the circuit After we replaced it it worked fine In the website http www geofex com Article Folders howto pdf the author discusses several tips for troubleshooting electronic circuits For NPN transistors used as amplifiers with no signal the collector is the most positive voltage usually by at least a couple of volts the base is somewhat lower and the emitter is invariably 0 5 to 0 7V 0 2 to 0 3 in germanium lower than the base If this is not true something is fouled up about the biasing on that stage For PNP transistors used as amplifiers with no signal the collector is the most negative voltage usually by at least a couple of volts the base is somewhat higher and the emitter is 10 invariably 0 5 to 0 7V 0 2 to 0 3 in germanium higher than the base If this is not true something is fouled up about the biasing on that stage For bipolar NPN PNP transistors if the collector base collector emitter or base emitter are exactly the same voltage either there is a circuit board short or the device is internally shorted and dead To check a bipolar transis
4. 4 OC3C INTS PES T3 INTS PES ICG INTZ PE7Z PAS ADS PA AD7 Pcl AS PC2 ALB PC3 11 PC4 AL2 PCS A13 PC hi4 PC7 ALS SCL INTO PDO SDA INT1 PD1 RXD1 INT2 PD2 TXD1 INT3 PD3 IC1 PD4 XCK1 1 P06 T2 P07 IN ADCO PFS ADC1 PF1 ADC2 PF2 ADC3 PF3 ADC4 TCK PF4 ADCS TMS PFS nDce TDO PF6 ADC7 TDI PF7 i r oops uno PG1 RD RUCC PGO WR oc2 ocic EXT2 uo BIA d PG2 ALE P61 PD P61 PD PEN AUREF AGND EGAI 28 8MM BEL CON 3 2 6 7K pxn No 0s 10 o Circuit Diagram VCC BAR H1 RESISTOR D1 LM335 TO92 U2 52 21 RESET XTAL1 XTAL2 TOSC1 PG4 TOSC2 PG3 1 9 2 10 11 PC4 A12 PC5 A14 PC6 A14 PC7 A15 ADCO PFO ADC1 PF1 ADC2 PF2 ADC3 PF3 ADC4 TCK PF4 ADC5 TMS PF5 ADC6 TD0 PF6 ADC7 TD1 PF7 AVCC MEGA128 8MM PA1 AD1 PA2 AD2 PA3 AD3 PA4 AD4 PA5 AD5 PA6 AD6 PA7 AD7 PB7 OC2 OC1C PB6 OC1B PB5 OC1A PB4 OCO PB3 MISO PB2 MDSI PB1 SCK PBO SS 5V jm de de js 51 VCC BAR 46 45 mai 472 17 T6 D2 DIODE 13 12 11 2 MOTOR AC 10 Q3 LJ wv U3 1 OUT Vcc GND Motion Sensor BlockDiagram Garry Jackson and Jason Jocson 3 23 2006 Fan Control Block Diagram The fan
5. Automatic Temperature Control System San Jose State University Department of Mechanical and Aerospace Engineering ME106 Fundamentals of Mechatronics Professor Burford Furman Ph D Submitted By Garry Jackson and Jason Jocson May 16 2006 Table of Contents OP s c cuu E M C 2 Snitadm T 3 TRO UC Oli dot cna tpe ena chs de tdeo 4 ela a s dato NND P MH 5 COLE DA SAS RE assent occa ere ins 6 BlocKDiagram issues etaient iii tenta asile ia niet 7 DOS EI ON oda ena td mon EIE MMC Ma M SE EE 8 ITS TOON yi EE 8 Problems Bneco ntered e os c ne ciate et aE acids ee aaa ee ae 10 Building Ups initie Nine 10 Conclusion Coto eren ope etii ob mof copa ss Meu orae 11 sisse te e e o mue ne ne nn 13 ADDED muet 14 Software PLO SAI ee entr URDU ee 14 Summary In the spring 2006 Mechatronics class at San Jose State University our group designed a project that implemented what we learned over the course of the semester It became our goal to materialize a system that employed a microcontroller sensors and actuators
6. Olimex AVR MT128 Similar to the STK500 board this unit is programmable via JTAG ports behind the unit connect to a PC via a USB cable The MT 128 is Equipped with an LCD display capable of outputting status messages character strings or any other information a user wishes to display In addition to the LCD the MT 128 has other usable features such as 6 pushbutton switches a relay and buzzer As the main component of the project this unit controlled an external circuit that would function as a temperature controller utilizing a motion detector sensor a temperature sensor and a motorized fan Schematics 12UDC SURC y 61 0B164 Jl 0 uF 25UDC c alca ee CopurightcCo 208 OLIMEX Ltd Http Uuuu 1 com dev 50 RESET t SE 32768Hz POI PDO XCKB AINS OC3A AINL OC3B INT 4 OC3C INTS TS INT IC3 INTZ SCL INTO SDRZINTI 4 RXD TXD FREQ T2 IN Ko ADCO ADCL ADCZ ADCS TCK 50 eT ADC2 ADCO AREF hs Jon ko ar 1N4148 n 54 3 Ris 22K 22k 2 B4 RESET XTALL XTAL2 TOSC1 PG4 TOSC2 PG3 DALLAS EXTL T2 i 13 Ti CKI 12 11 SOAVINTI 10 SCL INTE INT 8 2 T3 INTS 5 OC3B INT 3 XCKO AING 2 1 RXDG PDI PEG TX0G PO0 PEL XCKB AING PE2 OC3SA AINL PES B INT4 PE
7. control allow the user to set the fan to change speeds automatically depending on if Motion Sensor Temperature Sensor Possible chips include there is motion in the room and Possible chips include NO 0518520 3pi CHOSE the temperature difference that is 319520 Sp in the room gt AVR MEGA 128 Microcontroller e Motor There will be an set of This will run at 3 speeds switches that will allow the and two directions which user to say which speed will be controlled using the they want the fan if different microcontroller h bridge then the automatic settings and varying the duty 28 v Optional An LCD that will output the temperature of the room what speed the fan is going and which direction Also if the motion sensor is tripped or not Temperature Difference Motion Sensor Fan Speed 2 Active 1 4 Active 2 6 Active 3 4 Deactive 1 8 Deactive 2 12 Deactive 3 Description The initial function of this project is to simulate an automatic temperature control system that could be used in closed areas where ambient temperatures fluctuate However in order to save electricity a motion sensor that is integrated into the circuit is used to activate a variable speed fan which operates either at the users desired setting or an automated setting that is dependent on the temperature difference of the room s measured temperature and an internally set temperature d
8. etermined by the user In the user manual mode a motion sensor enables the circuit to be set at a specific fan speed to cool the room As long as there is a presence that the motion detector senses the fan will continue cool the room at its set speed If the user leaves the room with the fan on the motion detector will disable the fan and turn it off to save electricity In the automatic mode a motion sensor will enable the circuit to actuate a fan to cool the room automatically If the temperature difference in the room is 1 5 degrees from its set point the fan will automatically spin at 1 3 of its speed If the temperature difference is between 6 10 degrees from its set point the fan will spin at 2 3s of its speed If the temperature difference is greater than 10 degrees from the set temperature the microcontroller will set the fan to its full speed to cool the room the fastest Methodology When taking on a new electronics project it is important to carefully organize the methods in which the project must be performed Because there can be various systems and subsystems to deal with it is best to break the systems down into smaller manageable tasks to complete In putting together our project we chose to approach it by segmenting it in terms of hardware procedure and software procedure When building the temperature control system I prepared a workspace that could accommodate the tools equipment and materials that were required f
9. lization Func7 In Func6 In Func5 In Func4 In Func3 In Func2 In Func1 In Func0 In State7 T State6 T State5 T State4 T State3 T State2 T Statel T State0 T PORTE 0x00 DDRE 0x00 Port F initialization Func7 In Func6 In Func5 In Func4 In Func3 In Func2 In Func1 In Func0 In State7 T State6 T State5 T State4 T State3 T State2 T Statel T State0 T PORTF 0x00 DDRF 0x00 Port G initialization Func4 In Func3 In Func2 In Funcl In FuncO In State4 T State3 T State2 T Statel T State0 T 16 PORTG 0x00 DDRG 0x00 Timer Counter 0 initialization Clock source System Clock Clock value Timer 0 Stopped Mode Normal top FFh OCO output Disconnected ASSR 0x00 TCCRO 0x00 TCNTO 0x00 OCRO 0x00 Timer Counter 1 initialization Clock source System Clock Clock value Timer 1 Stopped Mode Normal top FFFFh OCIA output Discon OCIB output Discon OCIC output Discon Noise Canceler Off Input Capture on Falling Edge Timer 1 Overflow Interrupt Off Input Capture Interrupt Off Compare A Match Interrupt Off Compare B Match Interrupt Off Compare C Match Interrupt Off TCCR1A 0x00 TCCR1B 0x00 TCNT1H 0x00 TCNT1L 0x00 ICR1H 0x00 ICR1L 0x00 OCRIAH 0x00 OCRIAL 0x00 OCRIBH 20x00 OCRIBL 0x00 OCR1CH 0x00 OCR1CL 0x00 Timer Counter 2 initialization Clock source System Clock Clock value Timer 2 Stopped Mode Nor
10. mal top FFh OC2 output Disconnected TCCR2 0x00 TCNT2 0x00 OCR2 0x00 17 Timer Counter 3 initialization Clock source System Clock Clock value Timer 3 Stopped Mode Normal top FFFFh Noise Canceler Off Input Capture on Falling Edge OC3A output Discon OC3B output Discon OC3C output Discon Timer 3 Overflow Interrupt Off Input Capture Interrupt Off Compare A Match Interrupt Off Compare B Match Interrupt Off Compare C Match Interrupt Off TCCR3A 0x00 TCCR3B 0x00 TCNT3H 0x00 TCNT3L 0x00 ICR3H 0x00 ICR3L 0x00 OCR3AH 0x00 OCR3AL 0x00 OCR3BH 0x00 OCR3BL 0x00 OCR3CH 0x00 OCR3CL 0x00 External Interrupt s initialization INTO On INTO Mode Rising Edge INT1 Off IT INT2 Off INT3 Off INT4 Off MINTS Off IT INT6 Off INT7 Off EICRA 0x03 EICRB 0x00 EIMSK 0x01 EIFR 0x01 Timer s Counter s Interrupt s initialization TIMSK 0x00 ETIMSK 0x00 Analog Comparator initialization Analog Comparator Off Analog Comparator Input Capture by Timer Counter 1 Off 18 ACSR 0x80 SFIOR 0x00 ADC initialization ADC Clock frequency 125 000 kHz ADC Voltage Reference AREF pin ADMUX ADC VREF TYPE ADCSRA 0x86 LCD module initialization Icd_init 16 Global enable interrupts asm sei Icd_gotoxy 0 0 goto the top left corner lcd putsf Intro write intro me
11. motion state motion state number 4 4 else if motion_laststate motion_state amp amp motion_state_number 1 motion_laststate motion_state motion_state_number 0 This set of if else look at the desired temp and the temp being read to decide what speed the fan should be if motion_laststate active amp amp temp c diff 2m active 81 Fan Speed temperature varience if motion sensor is active fan speed 3 else if motion laststate active amp amp temp c diff 2m active 52 Fan Speed temperature varience if motion sensor is active fan speed 2 else if motion laststate active amp amp temp c diff2m active 82 Fan Speed temperature varience if motion sensor is active fan speed 3 if motion laststate inactive amp amp temp c diff m inactive s1 Fan Speed temperature varience if motion sensor is active fan speed 1 else if motion laststate inactive amp amp temp c lt inactive 52 Fan Speed temperature varience if motion sensor is active fan speed 2 else if motion laststate inactive amp amp temp diff2m inactive s2 Fan Speed temperature varience if motion sensor is active fan speed 3 if fan_speed 1 FAN_SPEED1 1 turn the low speed on FAN_SPEED2 0 turn the medium speed off FAN SPEED3 20 turn the high speed off j 20 if fan_speed 2 FAN_SPEED1 0 turn the low speed off FAN SPEED2 1 turn the medium speed o
12. n FAN SPEED3 20 turn the high speed off if fan_speed 3 FAN_SPEED1 0 turn the low speed off FAN SPEED2 20 turn the medium speed off FAN SPEED3 1 turn the high speed on j if motion_laststate active check state of motion laststate and set motion_display 1 if active this shows a 1 or 0 on the display depending on which one is set motion_display 1 else motion_display 0 Noad the top line into the buffer for lcd puts sprintf replace the u with the number in the variable temp_c and fan_speed sprintf Icd_buffer Temp 3u Speed 1u temp_c fan_speed clear clear the display gotoxy 0 0 move to the top left lcd puts lcd buffer write the buffer to the display sprintf lcd buffer MontionSensor 6u motion display gotoxy 0 1 lcd puts lcd buffer button loop 0 while button loop 200 button loops runs every 50ms for 200 times and the main loop starts again if B1 0 Af bl or top button pressed go into auto mode control autoz YES control state 1 if B2 0 b2 or left button pressed turn fan to speed 1 and auto off control_auto NO fan_speed 1 control_state 0 if B3 0 63 or middle button pressed turn fan to speed 1 and auto off control_auto NO fan_speed 2 control_state 0 j 21 if B4 0 Af b4 or right button pressed turn fan to speed 1 and auto off control auto NO fan speed 3
13. or the project By clearing a large area on my desk I placed soft absorbing cloth across the workspace so that any loose materials will not easily roll of the desktop in the event of any parts or pieces becoming loose to bounce and roll off the desk The soft material can absorb any stray moving components and catch it before it gets lost This prepared me to take the necessary steps in getting ready for the assembly of the project Our main source of instruction in building the circuit was to follow the schematic we generated by using MultiSim After populating the breadboard with the 2N3904 transistors and resistors we applied 5 voltage through the circuit to simulate the controller sending the voltage coming from the mictrontroller We were able to get 3 different voltage outputs to the fan which would represent a fan speed at each stage The transistors would act as an electronic switch that when triggered it would open the 12V supply to the fan At each stage we inserted resistors on 2 of the 3 stages to reduce the voltage going to the fan This would result in a Lo Med and Hi setting The temperature sensor and the motion sensor both operate on 5V and have one output pin The Vcc and Ground pins were then connected directly on the breadboard and the output pin was tied to the microcontrollers input The Motion sensor was tied to the one of the port pins while the temperature controller was connected to the ADC This would allow for the cont
14. roller to use a closed feedback system where the temperature sensor would feed a voltage into the ADC and the microcontroller would compare it to a setpoint temperature fixed inside the microcontroller The microcontroller would then take the comparison and determine what speed the fan should go to by checking against an index of temperature differences If the measured temperature was within 2 degrees of the setpoint it would trigger the Lo setting of the fan If the measured temperature was within 3 5 degrees of the set temperature it would trigger the Medium setting of the fan circuit and any temperature 6 degrees or greater it would trigger the maximum output 12V to the fan 9 Problems Encountered Building tips 1 No power ac voltage is not reaching the circuit By measuring the voltage across various resistors pin ports and IC leads we were able to troubleshoot and determine the culprit of not having any power to our circuit Bad soldering soldering leads onto our sensors and fans may have bad solder joints an can cause a bad connection for power continuity throughout the circuit Wires go the wrong places sometimes leads would be placed into the wrong row of a breadboard and would cause a misconnection or open circuit Wrong part or parts put in the wrong places the resistors we used may have been mistaken for a wrong value Sometimes if we need a IK resistor we got mistaken by reading the color codes as a 10K
15. s asm equ __Icd_port 0x15 PORTC endasm include lcd h External Interrupt 0 service routine interrupt EXT_INTO void ext intO isr void Place your code here define ADC_VREF_TYPE 0x00 Read the AD conversion result unsigned int read_adc unsigned char adc_input ADMUX adc_inputIADC_VREF_TYPE Start the AD conversion ADCSRAI 0x40 Wait for the AD conversion to complete while ADCSRA amp 0 10 0 ADCSRAI 0x10 return ADCW Declare your global variables here define MOTION_SENSOR PORTB 3 define FAN_SPEED1 PORTB 4 define FAN_SPEED2 PORTB 5 define FAN_SPEED3 PORTB 6 define Bl PINA O define B2 PINA 1 define B3 PINA 2 define B4 PINA 3 define B5 PINA 4 const unsigned char Intro Fan Controller Version 1 0 char buffer 33 Buffer for storing output for the LCD display unsigned char motionint Motion sensor checking loop number unsigned char motionrun Motion sensor high returns per loop unsigned char motion laststate Last motion sensor state unsigned char motion state Current montion sensor state unsigned char motion state number Number of runs in current state reading unsigned char motion display Display text for if the display on or off unsigned char temperature Temperature ADC reading unsigned char temp c Temperature in c unsigned char temp desire 30 Desired Temperature unsigned char temp c diff Tempera
16. sor in the corner of the room It was an idea to use an 1157 11 automotive bulb to place near the temperature sensor that would simulate heat from the sun to trigger the the fan to an appropriate speed Ultimately we were satisfied that our project was able to function properly and do what it was designed to do 12 References http www geofex com Article Folders howto pdf http home iae nl users pouweha Icd Icd0 shtml pin_assignment http www olimex com dev images avr mt128 sch gif 13 Appendix Software Program Esse P k k k k k k k k K kk k k k K k k K K K K This program was produced by the CodeWizardAVR V1 24 6 Professional Automatic Program Generator Copyright 1998 2005 Pavel Haiduc HP InfoTech s r l http www hpinfotech com e mail office hpinfotech com Project ME 106 Fan Controller Version 1 0 Date 5 10 2006 Author Garry Jackson and Jason Jocson Company Comments Reads if there is motion in a room and what the temperature is and determines the speed of the fan Output if there is motion the temperature and the fan speed to the LCD display Chip type ATmegal28 Program type Application Clock frequency 8 000000 MHz Memory model Small External SRAM size 0 Data Stack size 1024 3e ke 2 k k k k k k K Kk K include lt mega128 h gt include lt delay h gt include lt stdio h gt Alphanumeric LCD Module function
17. ssage to display delay ms 5000 pause 5seconds while 1 temperature read adc 0 Read the ADC value for the temperature sensor temp c temperature 14 Convert the ADC temperature value to c temp c diff ztemp c temp desire Find the difference between measure and desired temperature if control auto YES If control yes then check motion sensor and select fan speed motionint 0 clear motionint counter for while loop that checks for motion motionrun 0 clear motionrun counter for while loop that checks for motion while motionint lt 4 run this loop until motionint 4 and exit if PINB 3 1 check if there is signal on pinb 3 which is the motion sensor motionrun if the motion sensor is active increment motionrun motionint increment motionint for next while loop delay_ms 250 wait 25 seconds before the next check if motionrun gt 0 if the motion sensor went hi during one of the 4 checks set motion state active motion state active if motionrun 0 if motionrun 0 set it to inactive showing that the sensor did not pick up movement motion state inactive 19 if the current state is not equal to the last state this function will increment motion state number this if else is designed for the circuit doesn t go between active inactive over and over because of false reasing or someone keeps coming in and out of the room very frequently if motion laststate 2
18. tor read the collector voltage short the base to the emitter with a clip lead The collector voltage should go up except for cases where the collector is tied to the power supply In that case the emitter will go down significantly Measure the power voltages of IC s directly at the pins of the IC Op amps used as linear amplifiers must have the negative input and the positive input at the same voltage a few millivolts of the positive input If this is not true the op amp is dead or the circuit board is fouled up some way not true if it s used as a comparator Op amp positive and negative inputs and output pins should usually all be between 2 and 7 volts DC with respect to ground in single battery systems for linear amplifier op amps not including some special rail to rail op amps comparator use and some precision rectifiers Conclusion Upon the completion of our project we were happy that it was able to function correctly The circuit design and software debugging were the most difficult to implement but once it started to work the trouble became worthwhile and was very rewarding for our group If we had more time to complete the project we could make a display that would look more practical rather than just have some electronic breadboard populated with transistors resistors and capacitors Instead we can cover the circuit and make a display of a model bedroom that had an overhead fan with the temperature sen
19. ture Difference unsigned char fan speed Fan Speed unsigned char button loop Loop number for button reading unsigned char control auto unsigned char control state Control State is used for auto mode or manual fan speed Fan Speed Temperature Difference unsigned char m active 51 2 set the temperature variation 15 unsigned char m active s2 4 set the temperature variation unsigned char m inactive 81 4 set the temperature variation unsigned char m inactive s2 8 set the temperature variation void main void Declare your local variables here Input Output Ports initialization Port A initialization FuncO In Funcl In Func2 In Func3 In Func4 In Func5 In Func6 Out Func7 In State0 T State1 T State2 T State3 T State4 T State5 T State6 0 State7 T PORTA 0x00 DDRA 0x40 Port B initialization Func7 Out Func6 Out Func5 Out Func4 Out Func3 In Func2 In Funcl In FuncO In State7 0 State6 0 State5 0 State4 0 State3 T State2 T State1 T StateO T PORTB 0x00 DDRB 0xF0 Port C initialization Func7 In Func6 In Func5 In Func4 In Func3 In Func2 In Func1 In FuncO In State7 T State6 T State5 T State4 T State3 T State2 T Statel T State0 T PORTC 0x00 DDRC 0x00 Port D initialization Func7 In Func6 In Func5 In Func4 In Func3 In Func2 In Func1 In Func0 In State7 T State6 T State5 T State4 T State3 T State2 T Statel T State0 T PORTD 0x00 DDRD 0x00 Port E initia
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