- Sacramento
Contents
1. 5V LIN ao EE 0 1 uF volt T 7805 2 GND AN L 1 PC6 PC5 28 _USART Input _ gt ppo PC4 27 1 l el SC 3 PD1 PC3 26 ay LeDpinii 4 PD2 PC225 8 F LCDpin12 5 ppg DCH 24 1 VCC 2 OUT Iw 5 LCD pints 6PD4 8 ona LM34 5 SVT _ NCC GND 22 3 GND 6 8 GND C AREF 21 7 14 7456 MHz 8 9 PB6 lt AVCC 20 8 10PB7 PB519 LCD LCD pini4 m 14 11 PD5 PB4 18 WEEN 1N4003 10 LCD pin6___ 49 ppg PB3 17 Motor A 11 ohni app PB216 S 12 14PBO PBI15 L H G 2N7000 13 volt H s 14 100K 15 16 Figure 4 2 Circuit Diagram of Fan Control System 12 PWM output is given to gate terminal of N channel MOSFET 2N7000 from microcontroller MOSFET Metal Oxide Semiconductor Field Effect Transistor is high switching speed power switch This MOSFET switches on and off at PWM frequency and controls the voltage across motor As shown in diagram positive terminal of motor is connected to 9V and negative terminal is connected to drain of MOSFET When MOSFET is on the motor starts to gain speed and off then motor looses speed 100Kohm resistor is connected from gate of MOSFET to ground to pull the gate to ground When ATmegal68 is not driving the motor this pull down resistor separates motor from microcontroller and other circuit Fly back diode 1N4003 is connected in parallel with motor as shown in the circuit diagram When the MOSFET is off due to inductive coil of 30 motor there may2. 17 Chapter 3 MOTOR CONTROL WITH MICROCONTROLLER This project is based on cooling fan design of desktop computers and laptops I have used following components for the implementation of this project l 2 9 Microcontroller ATmega168 Temperature sensor LM34 Crystal oscillator Voltage regulator L7805 LCD MOSFET 2N7000 Diode 1N4003 Brushless DC Motor BLDC Programmer 10 Resistors capacitors breadboard and jumper wires 3 1 Temperature Sensor Integrated circuit temperature sensors are classified in two categories analog temperature sensors and digital temperature sensors Analog temperature sensors are divided in two categories depending on their output voltage output temperature sensors and current output temperature sensors 1 LM 34 is a precision Fahrenheit temperature sensor manufactured by National Semiconductor Figure 3 1 shows plastic package LM34 and basic Fahrenheit temperature sensor 3 18 tr Ne 5V T0 20V LM34 Vout 10 0 mn E BOTTOM VIEW Figure 3 1 Package LM34 and Basic Fahrenheit Temperature Sensor 3 The output voltage of LM34 is linearly proportional to the Fahrenheit temperature The linear output is 10 0 mV F scale factor It draws less than 90 uA from supply and operates on 5 to 30 volts This low cost device operates over the temperature range of 50 to 300 F It has low impedance output and low self heating less than 0 2 F in still air
3. DB6 IR6 iR2 X XaceX Xacz X OR XDR DB5 IRS X_IR1 X Xacs Xac iX ORX XORI DB4 R4 X iro E KacoX ORAC XORO Instruction register IR Busy flag BF and Data register DR write address counter AC read read Figure 3 4 4 bit Transfer between ATmegal68 and LCD 5 Pin E tells LCD to start data read write Logic 0 on R W is for write and 1 is for read Logic 0 on RS pin selects instruction register for write and if flag is busy then it selects address counter for read Logic 1 on RS pin selects data register for read and write DB 7 4 is used for data transfer between ATmegal68 and LCD These bits should be transferred first for 8 bit operation then DB 3 0 transfer takes place DB 3 0 used only for data transfer during 8 bit operation 5 3 5 MOSFET 2N7000 2N7000 is an N channel enhancement mode metal oxide semiconductor field effect transistor manufactured by Fairchild 2N7000 is a reliable and rugged voltage controlled small signal switch so well suited for project This device has high saturation capability Figure 3 5 shows pin description of 2N7000 6 21 Figure 3 5 Pin Description of 2N7000 MOSFET 6 3 6 Brushless DC Motor BLDC BLDC electric motors are commutated electronically they do not use brushes so called brushless DC motor These motors provide better speed versus torque characteristics noiseless operation and high efficiency over brushed DC motors and induction motors Mag
4. avrdude input file project_code hex auto detected as Intel Hex avrdude writing flash 11138 bytes Writing HHHHHLHHH HHH HH HHH HHH HHH HHEH HHH HH HHHHHHH i 1007 avrdude 11138 bytes of flash written avrdude verifying flash memory against pro ject_code hex avrdude load data flash data from input file project_code hex avrdude input file project_code hex auto detected as Intel Hex avrdude input file project_code hex contains 11138 bytes avrdude reading on chip flash data Reading CC i 1007 avrdude verifying avrdude 11138 bytes of flash verified avrdude done Thank you Figure 5 3 Programming the ATmegal68 with Command Prompt Figure 5 4 shows the USB to serial communication port COM1 used to connect to programmer and I described this communication port in makefile to tell the 38 AVRDUDE program to which communication port the ATmegal168 is connected through the programmer File Action View Help e e lelplRHselelsgee a Mu Notebook gt E Batteries gt 0 Bluetooth Radios gt BR Computer gt Disk drives gt RY Display adapters DVD CD ROM drives gt De Human Interface Devices gt gy IDE ATA ATAPI controllers gt IEEE 1394 Bus host controllers gt 2 Imaging devices gt SP Jungo gt lt 2 Keyboards gt D Mice and other pointing devices gt HE Modems p p D p gt E Monitors gt AP Network adapters 727 Ports COM amp
5. 3 16 bit Timer Counter1 with PWM The 16 bit timer counter unit generates pulse width modulation PWM output for motor control A simplified block diagram of 16 bit timer counter is shown in Figure 2 3 66 99 An n in block represents timer counter number and x represents output compare unit channel 2 Count TOVn Clear Int Req Direction CITE a Clock Select Edge Detector BOTTOM f 1 From Prescaler Timer Counter emirs OCnA int Req i EE dE Generation OCRnA d i rr ocnB om H TOP int Req om lt EZ i pass amp i a OCRnB H From Analog a Comparator Ouput H ICFn Int Req U H Edge Noise En t Detactor Cancelar i 4 TCCRnA TCCRnB Figure 2 3 16 bit Timer Counter Block Diagram 2 This mode includes 16 bit register called Output Compare Register OCR1A B requires special procedure while accessing Timer counter control registers are 8 bit Timer counter can be clocked externally via clock signal on T1 pin or by internal clock The clock select bits CS12 0 in TCCR1B Timer Counter Control Register B defines which clock to use internal or external OCR1A B are compared with timer counter and waveform generator and uses that result is used to generate PWM output on the OC1A B Output Compare Pin The maximum timer counter TOP value is assigned to OCRIA register so this register can not be used for generating a PWM output for
6. February 2008 12 Mike Robbins Motors and Microcontrollers 101 NerdKits Retrieved on October 8 2010 From the World Wide Web http www nerdkits com videos motors_and_microcontrollers_101 47 13 Sourceforge net WINAVR Retrieved on November 10 2010 From the World Wide Web http winavr sourceforge net 14 Muhammad Sadiq Bin Sahari Programmable Switching Power Supply pp 19 24 May 2009 15 Eric B Weddington WinAVR User Manual 20050214 February 2005 Retrieved on November 10 2010 From the World Wide Web http winavr sourceforge net WinA VR user manual html 16 Joerg Wunsch AVRDUDE January 15 2010 Retrieved on November 16 2010 From the World Wide Web http www nongnu org avrdude user manual avrdude html
7. LPT I Prolific USB to Serial Comm Port COM1 DI Processors E SD host adapters ai Sound video and game controllers JE System devices 8 Universal Serial Bus controllers Figure 5 4 USB to Serial Communication Port 1 39 5 3 2 Results The following images describe results for this project Figure 5 5 shows fan control system temperature sensor senses the lab temperature and controls motor fan temperature in degree Fahrenheit and PWM output is shown on LCD Figure 5 5 Fan Control System 40 Figure 5 6 Figure 5 7 and Figure 5 8 shows variation in output voltage of temperature sensor in volts on multimeter with respect to lab temperature and LCD shows temperature in degree Fahrenheit and PWM output Figure 5 6 Output Voltage on Multimeter 1 41 Figure 5 7 Output Voltage on Multimeter 2 42 Figure 5 8 Output Voltage on Multimeter 3 Output voltage of temperature sensor changes with temperature and this analog voltage value is given to ADC of microcontroller microcontroller changes PWM duty cycle output with respect to this voltage differences and gives it to MOSFET to control the motor fan 43 Figure 5 9 Fan Control System with Temperature in Degree Celsius 1 44 Figure 5 10 Fan Control System with Temperature in Degree Celsius 2 I implemented the whole design to show temperature in degree Celsius too Figure 5 9 and Figure 5 10 shows the same working project with temperature
8. and EEPROM of Atmel s AVR series of microcontrollers supported by serial programming protocol using the in system programming technique ISP With AVRDUDE users can use an interactive terminal mode or command line to 35 write to fuse bits lock bits flash EEPROM or signature bytes of AVR microcontroller This program was written by Brian S Dean as a private project of an in system programmer for AVR microcontroller 16 AVRDUDE supports many programmers like STK500 STK600 avr910 avr109 and PPI Parallel Port Interface programmers too AVRDUDE can be configured to work with any of these programmers by entering its specifications directly on command line or by editing configuration file 16 AVRDUDE options which should be considered while programming are as follows p partno This option is mandatory to write in makefile that tells AVRDUDE program which AVR microcontroller is connected to the programmer In Figure 5 1 third line shows how AVRDUDE is configured p m168 tells programmer that ATmegal68 is connected to programmer 16 b baudrate That specifies RS 232 connection baud rate with respect to programmer used bh 115200 in Figure 5 1 shows 115200 bps bits per second baud rate is specified for the serial interface 16 c programmer id Figure 5 1 shows c avr109 specifies avr109 programmer to be used I also used STK500 to implement this project so in that case it should be replaced by
9. from different directory Last line tells to download hex file in microcontroller flash 5 1 3 Programmer s Notepad Programmer s notepad is an open source text editor comes with WinAVR It has many features and supports many programming languages For my project I used it for writing code in C in its text editor After writing you can compile code with the compiler WinAVR File Edit View fis Window Help i EN GES Line Endings Tose v Use Tabs 3 Makefile WinAVR Make All H member WinAVR Make Clean WinAVR Program Stop Tools Options project_code hex make C Ctrl Shift K cu atmegal6s f Iprintf_flt wl u vfsc p m168 b 115200 P COM5 roller delay o microcon oad project_code c microcontroller avr gcc GCCFLAGS LINKFLAGS o project_co avr objcopy j test O ihex project_code o pr project_code ass project_code hex avr objdump S d project_code o gt project_cod project_code upload project_code hex avrdude AVRDUDEFLAGS U flash w project_cod Figure 5 2 Programmer s Notepad Figure5 2 shows Programmer s Notepad For compile purpose Make AI generates hex file following the information from makefile Make Clean deletes all temporary files including hex file Program transfers hex file to the AVR microcontroller 5 2 AVRDUDE AVRDUDE AVR Downloader UploaDEr is a command line program for programming the flash
10. in degree Celsius on LCD 45 Chapter 6 CONCLUSION AND FUTURE WORK 6 1 Conclusion Fan control system with temperature sensor and microcontroller was successfully designed and implemented The working project use temperature sensor to monitor the lab temperature and based on that microcontroller controls speed of motor fan and continuously displays temperature on LCD This fan control system algorithm provides high efficiency low noise and low power consumption Knowledge regarding architecture of microcontroller and how different types of motor work in real time applications were gained Detailed knowledge of programming language C WinAVR complier PWM ADC and hardware and software interfaces for microcontroller was gained All goals were achieved and the complete working project can work as a part of cooling system of desktop computers 6 2 Future work In the current design more hardware and software interfaces can be added in such a way that the measured temperature can be transmitted on wireless transmitter or can be sent over internet This microcontroller can be programmed to control high efficiency motor loads used in industries ATmegal68 microcontroller can be designed to control several motors to make robotic arm Microcontroller can be used to make line follower obstacle avoiding robot or light tracer robot with the use of two de motors and few sensors 46 REFERENCES 1 Dogan Ibrahim Microcontroller Based Tempe
11. motor control This maximum counter value can be OxOOFF OxO1FF or Ox03FF depending on application Byte addressable 16 bit register OCR1A B can be accessed by AVR CPU via 8 bit data bus 2 2 3 1 Output Compare Unit The block diagram of output compare unit is shown in Figure 2 4 with waveform generator The 16 bit comparator compares OCR1x Output Compare Register with TCN1 Timer Counter 1 and if both are equal than generated match signal is given to waveform generator It generates waveform depending on compare output mode bits COM1x1 0 waveform generation mode bits WGM13 0 bits and TOP and BOTTOM values assigned to Output Compare Register OCR1x The OCR1x register is double buffered register in PWM mode and TOP value assigned describes the period time for waveform generation So OCR1x is compared to top or bottom of the counting sequence to generate glitch free symmetrical PWM pulses In double buffering the CPU has access to OCRIx buffer registers While reading it reads low byte first and then high byte Writing is done by writing high byte OCRI1xH first and then writing low byte second 2 DATA BUS 8 bit E E OCRnxH Buf 8 bit OCRnxL Bui 8 bit OCRnx Buffer 16 bit Register ey OCRnxH 8 OCRnxL 9 np it Register bi EE R me TCNTn 16 bit Counter bit OCRnx 16 J lt amp A 16 bit Comparator OCFnx mt eo TOP BOTTO
12. Chukka Siddharth Shah Jigar Bhatt Hardik Shah and engineers team at Nerdkits for providing all technical help to complete this project I am thankful to all faculty members of Electrical Engineering and Computer Science Department for helping me to finish my graduation at California State University Sacramento TABLE OF CONTENTS Page ACEO WISE EE v Laeken ix Eist of FIgUTES nolens an eaaa EEVA EIEEE a E ected E E ESAR R as x Chapter e INTRODUGTION sepone pisuna uou dete esa auie EEE h ea ee eee 1 MINIM te EE 1 1 2 P rpose of the Freet au sot NEEN sade dans de SEENEN haves vies thee 1 13 Significance OF the Projet EE 2 1 4 Organization of Report eene eNEERNN ENNEN NENNEN ENEE ee Sen et 2 2 ATMEGA168 MICROCONTROLLER ARCHTIECTURR scene 4 2 1 Pin Configuration of A Tmegealo ccc eee ee cece ence ence nee ee ene e ence 4 2 2 Block Diagram of Almesalop 0 cece cece ence eee e een ee ence nee eaenees 6 2 3 16 bit Timer Counter with DWM cece cece eee eee eee eee eneencnes 7 2 3 1 Output Compare EE sees See 8 2 3 2 Fast PWM Macher den egen eg deen eseu ae Davie deed de NEE tee 9 2 3 3 Resister IDESCIIDUON E 11 2 3 3 1 TCCRIA Timer Counter 1 Control Register A 11 2 3 3 2 TCCR1B Timer Counter Control Register B 11 2 4 Analog to Digital Converter 12 NEE RT EE 13 2 4 2 ADMUX ADC Multiplexer Selection Register 15 2 4 3 ADCSRA ADC Control and Status Register A 16 3 MOTOR CONTROL WITH MICROCO
13. Conversion Figure 2 10 ADC Timing Diagrams 2 2 4 2 ADMUX ADC Multiplexer Selection Register Bit 7 e 5 4 3 2 1 o ei REFS1 REFSO ADLAR CL mux2 Muxi Muxo j am Read Write RW RW RW F RW RW RW RW Initial Value o 0 0 H H H H H Figure 2 11 ADC Multiplexer Selection Register 2 16 Bit 7 6 REFS1 0 Reference Selection Bits These bits select voltage reference for ADC for my project it is 00 as AREF external reference voltage is used 2 Bit 5 ADLAR ADC Left Adjust Result Writing 1 to ADLAR bit adjusts result to left in ADC conversion result By default ADC data register conversion is right adjusted 2 Bit 3 0 MUX3 0 Analog Channel Selection Bits For my project these bits are 0000 represents ADCO is used as an analog input to ADC 2 4 3 ADCSRA ADC Control and Status Register A Bit 7 6 5 3 2 1 0 Go ADEN Anse ADATe ADF ADE SCT ADCSRA Read Write RW RIN RIN RAW RN RAW RIN RW initial Value 0 D 0 D D 0 0 0 Figure 2 12 ADC Control and Status Register A 2 Bit 7 ADEN ADC Enable Writing 1 to ADEN will enable ADC of the microcontroller Bit 6 ADSC ADC Start Conversion Writing 1 to this bit in free running mode starts the first conversion Write 1 to this bit each time to start single conversion mode 2 Bit 2 0 ADPS2 0 ADC Prescaler Select Bit For this project these bits are 111 so 128 division factor is selected for ADC prescaler
14. M gt Waveform Generator a WGMn3 0 COMnx1 0 Figure 2 4 Output Compare Unit 2 2 3 2 Fast PWM Mode The fast pulse width modulation mode provides high frequency waveforms and has single slope operation This single slope operation allows PWM mode to be used with digital to analog converter DAC applications rectification and power regulation The counter TCNT1 counts from BOTTOM to TOP value assigned to OCR 1x register 2 The PWM resolution in bits is given by the equation 1 10 _ log TOP 1 R FPWM log 2 This PWM resolution in bits can be given from 2 bit to 16 bit value assigned as TOP value to OCR1A In this mode counter is incremented until it reaches the value assigned to OCR1A WGM13 0 15 Then it is cleared in the following clock Figure 2 5 shows fast PWM mode timing diagram 2 OCRnx BOTTOM Update and TOVn Interrupt Flag Set and OCnA Interrupt Flag Set or ICFn Interrupt Flag Set Interrupt on TOP TCNTn OCnx l l l UU l l COMnx1 0 2 Ppp fofefp fp Figure 2 5 Timing Diagram Fast PWM Mode 2 Peri S OCRIA is used to define TOP in the timing diagram TCN1 signal shows single slope operation The diagram shows marks on signal TCNT1 when OCR1x and TCNT1 are equal and shows change in PWM output on OCnx This port will generate non inverted PWM if COM1x1 0 bits are set to 2 or will generate inverted PWM if COM1x1 0 bits are set to 3 The PWM freq
15. NTROLLER nl KT eeler 17 S DG Ty Stal SCI ALOl ton dee EE EE 18 3 3 Voltage Regulator LEUR gegen tie nt E EEEE TEES 18 DA E O EE 19 Ee MOSFET IN 000 cscs ss accoeseeuedon renter dua esgacnen ee E E e TEE Eite 20 3 6 Brushless DC Motor BEDE eegene ei 21 3 7 Pulse Width Modulation DWM eeeee ects ee eeeeenaeeeees 22 3 8 Variable Speed Control in BL DCkan 00 e eee ence eee ne en ees 24 4 DESIGN OF FAN CONTROL SYSTEM 26 4 1 Configuring ADC in ATmegal68 0 20 20 ce cee cee ence ce tenn nee ee nen seeee 26 4 2 PW MiAnitializauion E 28 4 3 Implementation of Fan Control System 28 5 MICROCONTROLLER PROGRAMMING ene en eens 32 ENEE Ee Ee 32 5 1 1 Installing WinAY Rig dee sevens cay ene KN dE ENEE dE Ae dE 32 GE MAK CMe ss caus ge ee eeh 32 5 1 3 Programmer s Notepad gg ENNEN ENEE SEENEN ENEE 33 KEEN dE RE 34 5 3 Programming and Results sie aiser rte eher AANER eh SNE 36 5 3 1 Programming of Almegalon cece cece eee ee eee eee en ees 36 D322 RESUS EE 39 6 CONCLUSION AND FUTURE WORK tee tabuesreneg guest d dg Eben dene sean es 45 E Cell EES 45 G22 TEE 45 LEE 46 viii Ji LIST OF TABLES Table 4 1 Input Channel Selections for ADC 1X 10 11 12 13 14 15 16 17 18 19 LIST OF FIGURES Page Figure 2 1 Pin diagram of ATmegal68 0 cece cee ee cece nee n cena eee ee eeees 4 Figure 2 2 Block Diagram of ATmegal68 cee eee scence eee e
16. Pulse Width Modulation PWM Pulse width modulation is most commonly used technique to control motor with digital output from ASIC Application Specific Integrated Circuit or MCU Microcontroller Unit PWM is a way of digitally encoding analog signal levels At 23 any given time the DC pulse logic level is either 1 or 0 so PWM is digital signal With the use of microcontroller ADC we can generate perfect duty cycle square wave that completely describes the analog voltage output from the temperature sensor Any analog value can be described in the series of on and off pulses and voltage or current source can drive motor by these series of pulses PWM is noise immune because it is digital signal usually noise is not strong enough to change the signal from logic 0 to logic 1 or vice versa 9 12 On High Level Off Low Level Le 90 Figure 3 8 PWM Signals of Varying Duty Cycles 9 Figure 3 8 shows PWM signals with varying duty cycles of 10 50 and 90 The first signal shows 10 means it is off for 90 of the signal period Therefore if I have 9 V supply voltage and 50 duty cycle signal then analog signal of 4 5 V results 9 Because of flywheel momentum and natural inertia motor runs at steady speed with microcontroller if the switching frequency is high The ratio of the on time to total time period is called duty cycle and time period is inverse of modulati
17. TEMPERATURE BASED FAN CONTROL Nayankumar K Patel B E Gujarat University India 2005 PROJECT Submitted in partial satisfaction of the requirements for the degree of MASTER OF SCIENCE in ELECTRICAL AND ELECTRONIC ENGINEERING at CALIFORNIA STATE UNIVERSITY SACRAMENTO FALL 2010 TEMPERATURE BASED FAN CONTROL A Project by Nayankumar K Patel Approved by Committee Chair Jing Pang Ph D second Reader Preetham Kumar Ph D Date ii Student Nayankumar K Patel I certify that this student has met the requirements for format contained in the University format manual and that this project is suitable for shelving in the Library and credit is to be awarded for the Project Graduate Coordinator Preetham Kumar Ph D Date Department of Electrical and Electronic Engineering iii Abstract of TEMPERATURE BASED FAN CONTROL by Nayankumar K Patel Electric motors are used in many real time applications Microcontroller controls these motors as programmed to perform in different environment Microcontroller can store and execute program to control motor and can take feedback from the motor for better performance The purpose of this project is to design motor controller using microcontroller with temperature sensor The temperature sensor will sense the temperature and gives data to microcontroller Microcontroller will control the speed of motor according to the temp
18. The plastic package TO 92 is better for measuring air temperature than surface temperature 3 1 3 2 Crystal Oscillator A crystal oscillator is an oscillator circuit that uses thin piece of quartz to generate electrical signal with precise frequency Most of electrical circuits needs precise clock signal to execute instructions on time I used crystal oscillator with 14 7465 MHz frequency for this project 3 3 Voltage Regulator L7805 Voltage regulator gives constant regulated voltage to circuit L7805 voltage regulator is used for to provide regulated output voltage 5V to microcontroller temperature sensor and LCD L7805 comes with short circuit protection and thermal shutdown for reliable operation Figure 3 2 shows pin configuration of L7805 4 19 ___ OUTPUT C __ _____ GROUND _ gt _ INPUT Figure 3 2 Pin Configuration of L7805 Top View 4 3 4 LCD Liquid Crystal Display LCD is used to display temperature of lab I used 16 pin LCD module which has HD44780 dot matrix LCD controller Figure 3 3 shows 16 Pin LCD Module used in this project It is 4 line 20 character wide LCD D Bus Figure 3 3 16 Pin LCD Module It allows 4 bit or 8 bit microcontroller interface DB 7 0 E R W and RS pins are used for communication with microcontroller ATmegal68 Figure 3 4 shows 4 bit transfer between microcontroller and LCD 5 20 RW E d NK J amp _ LSJ AA NM DB7 IR7 RW BEX Xac3 X E XDR3
19. a to output devices Microcontrollers are classified in 8 bit 16 bit or 32 bit microcontroller as per the data bits they handle in a single operation 1 1 2 Purpose of the Project The main purpose of this project is to design control system to control the speed of motor with change in temperature of the system In this project temperature sensor senses the lab temperature and generates analog output that is given to microcontroller Microcontroller converts the data in digital using analog to digital converter and controls speed of motor that is actually a fan for this project Microcontroller increases the fan speed with rise in temperature Using ATmegal68 microcontroller control different peripherals attached to its I O pins and display measured temperature on LCD Liquid Crystal Display Use WinAVR compiler to compile the code written in programming language C and generate hex file which is burned to microcontroller s flash memory with programmer 1 3 Significance of the Project Motor control with microcontroller is very interesting field of study Motor control is used in many applications in industry Particularly this type of approach is used in CPU Central Processing Unit fan of desktop and laptop computers for cooling purpose For these applications it is important to maintain minimum power consumption so turning off the motor while not needed A complete control system saves power by using temperature sensor to measure temperat
20. ad ev RENEN ANNE ENEE EEN dE ge Figure 5 3 Programming the ATmegal68 with Command Prompt 37 Figure 5 4 USB to Serial Communication Port 1 ccs cece cece eee eee 38 Figure 5 5 Fan NL EE 39 Figure 5 6 Output Voltage on Multimeter 1 40 Figure 5 7 Output Voltage on Multimeter 2 41 Figure 5 8 Output Voltage on Multimeter 3 42 Figure 5 9 Fan Control System with Temperature in Degree Celsius 1 43 Figure 5 10 Fan Control System with Temperature in Degree Celsius 2 44 Xi Chapter 1 INTRODUCTION 1 1 Introduction A microcontroller is a general purpose integrated circuit which contains microprocessor memory and input output devices Microcontrollers are used in microwaves remote controls cruise control system digital cameras cell phones laser printers answering machines telephones pagers refrigerators dishwashers and in other home appliances Microcontrollers are programmable devices Depending on application they may contain different type of memory flash memory that can be reprogrammed at user end or read only memory which is programmed at company Compiler compiles the code written in high level language and converts it in machine level language that can be written to microcontroller with the help of programmer Microcontroller executes this program takes input from the peripheral devices makes some calculations and take decisions according to the algorithms written in code and gives dat
21. atures it has 6 pulse width modulation PWM channels 6 channel 10 bit analog to digital ADC programmable universal synchronous asynchronous receiver transmitter USART interface master slave serial peripheral interface SPI and 2 wire serial inter integrated circuit I2C interface In my project I used 28 pin plastic dual in line package PDIP type of ATmegal68 2 2 1 Pin Configuration of ATmegal68 PCINTI4 RESET PCE O 1 PCINTIGRXD PDO D 2 PCINT17 TXD PD DA 28 0 PC ADCS SCLIPCINT13 27 0 PCA ADC4 SDA PCINT12 26 D PC3 ADC3 PCINT11 PCINTIB INTO PD2 O 4 25 D PC2 ADC2 PCINT10 PCINTIS OC2BINT1 PD3 0 5 240 PC1 ADC1 PCINTE PCINT20XCK TO PD4 O amp 23 0 PCO ADCOIPCINTE PCINTE XTAL1 TOSC1 PB6 2 p AVE PCINT7XTALATOSC2 PB7 10 19 0 PB5 SCKPCINTS PCINTZVOCOET1 PDS 11 18 0 PBA MISOPCINTA PCINT22 OCOMAIND PDS 12 17 0 PB3 MOSVOC2APCINT3 PCINT23 AIN1 PDT O 13 16 0 Pa SS 0C 1B PCINT2 PCINTOICLKQNICP1 PBO D 14 15 O P81 OCTA PCINT Figure 2 1 Pin diagram of ATmegal168 2 VCC VCC is digital supply voltage that is 5 V for this project GND GND is ground pin of ATmegal68 Port B PB7 0 It is 8 bit bi directional input output port All ports have multifunction and can be used according to application PB6 is external clock input to ATmegal168 or it can work as chip clock oscillator pin 1 PB7 is chip clock oscillator pin 2 PBO is used as program run mode switch i
22. be huge voltage that can produce spark and may damage other components Therefore fly back diode plays an important role in protecting other circuit 11 12 san SR Set and Enable ADC Timer for fast PWM mode UART LCD Read Temperature Sensor take number of samples and average them Start PWM Calculate difference in temperature Increase PWM output with increase in temperature and vice versa e temperature on LCD all time yf Figure 4 3 Flow Chart Diagram of Fan Control System 31 Microcontroller continuously monitors the temperature and controls speed of motor by changing the duty cycle of PWM The speed of motor fan is controlled by the duty cycle of PWM that drives two winding coils of motor fan alternately Depending on the factors like acoustic noise controllable speed range and efficiency the PWM frequency can be chosen in between 18 KHz to 60 KHz 18 KHz is higher than the audible range of human ear so no acoustic noise will occur Higher efficiency can be obtained by choosing high frequency for PWM Figure 4 3 shows flow chart of fan control system When microcontroller executes program it sets and enables ADC Timer 1 for fast PWM LCD and UART Microcontroller continuously reads temperature and averages them after sampling It calculates difference in temperature and by considering this difference it will increase PWM
23. bit ADPS2 0 for the division factor bits These all bits are set in ADCSRA register for this project Both ADMUX and ADCSRA values are written to microcontroller with a programming code in language C 2 4 2 PWM Initialization This includes enabling PWM controller configuring 16 bit timer 1 mode and configuring the direction of PWM output Timer counter control register A TCCRIA Timer counter control register B TCCR1B output compare register A OCR1A are configured in C code to make PWM mode work with ATmega168 microcontroller for fan control application 2 9 4 3 Implementation of Fan Control System Figure 4 2 shows circuit diagram of fan control system Crystal oscillator is connected in between pin 9 PB6 and pin 10 PB7 of ATmega168 those are pins if we want to provide external clock to the microcontroller I used 0 1 uF bypass capacitor on the output pin 5 V of the voltage regulator L7805 to smooth out the supply voltage to microcontroller and LCD Vout pin of temperature sensor LM34 is connected on pin PCO which is ADCO of all ADC input pins Pin 3 of LCD is connected to ground via 1Kohm resistor to set the contrast of the LCD to display temperature on LCD Pins from PD2 to PD7 are connected to remaining LCD pins used for data and control signals between LCD and ATmegal168 microcontroller 12 11 29
24. c stk500 P port 36 Specifies on which port the programmer is connected Figure 5 1 shows P COMS so programmer is connected on laptop s COMS port u It will disable the reading out of fuses before programming and verifies they have not been changed 16 U memtype OP filename format This is important to specify while you are doing any operation on AVR microcontroller with AVRDUDE program This specifies memory type flash eeprom 66199 66 29 fuse etc OP specifies operation type to be performed read write or verify by r w 66 99 v respectively Figure 5 1 last line shows DI U flash w project_code hex a specifies project_code hex file is going to be written to the flash of ATmega168 a is an optional format field format of the file to be read or written specifies auto detect so AVRDUDE will detect the file format automatically from that directory 16 5 3 Programming and Results 5 3 1 Programming of ATmegal68 For this project I programmed ATmegal68 with programmer STK500 and avrl09 I have made makefile in the same directory where I put the project code for fan control system Makefile includes all description like how the program should be compiled with linking other files and at the end which file should be generated I put header files for LCD and UART in other directory and put both of these folders under one directory Figure 5 3 shows how to call the makefile to progra
25. e eee en cees 6 Figure 2 3 16 bit Timer Counter Block Diagram ec ce ece sees ee eee eens 7 Figure 2 4 Output Compare Unit EE 9 Figure 2 5 Timing Diagram Fast PWM Mode 10 Figure 2 6 Timer Counter 1 Control Register A 11 Figure 2 7 Timer Counter Control Register RB 11 Figure 2 8 Block Diagram of ADC Almesealon ereere 12 Figure ER 14 Figure 2 10 ADC Timing DiagramSs sssssssssrrereesseesrrrrrereeereeerreeeer 15 Figure 2 11 ADC Multiplexer Selection Register ccs cee eee ee eee es 15 Figure 2 12 ADC Control and Status Register A 16 Figure 3 1 Package LM34 and Basic Fahrenheit Temperature Sensor 18 Figure 3 2 Pin Configuration of L7805 Top View 19 Figure 3 3 16 Pin LCD NEEN 19 Figure 3 4 4 bit Transfer between ATmega168 and LCD 20 Figure 3 5 Pin Description of 2N7000 MOSPET cece eeeeeee ee eee es 21 Figure 3 6 BLDC Motor Transverse Secton cesses eee ence ene ee trees 21 Figure 3 7 BLDG EE 22 20 St 22 23 24 25 26 2T 28 29 30 31 32 33 34 Figure 3 8 PWM Signals of Varying Duty Cycles 23 Figure 3 9 BLDC Fan Speed Control with DWM ccs cee ee ence ee eeeeneee 24 Figure 4 1 Block Diagram of Fan Control Svstem cece eens ee eee 27 Figure 4 2 Circuit Diagram of Fan Control System 29 Figure 4 3 Flow Chart Diagram of Fan Control System 30 Fig re 5 l Makefile Example sssri enn pinid egw EEE ee 33 Figure 5 2 Programmer s Notep
26. erature When temperature reaches above certain value the microcontroller will turn on the motor Increase in temperature will result in increase of speed of motor The expected functional project will store program in microcontroller and execute it in order to control the speed of motor according to data read from temperature sensor Committee Chair Jing Pang Ph D Date iv ACKNOWLEDGMENTS I would like to thank Dr Jing Pang for providing me an opportunity to work on this project which has been a great learning experience I thank her for providing all necessary resources and help to finish this project She always encouraged me to work hard and provided all help for the completion of this project Without her guidance help and support this project would not have completed successfully I really appreciate her help during different phases of project I would like to thank Dr Preetham Kumar Graduate Coordinator of Electrical and Electronic Engineering for his valuable guidance in project and for reviewing my report and providing valuable suggestions I would like to thank Dr Suresh Vadhva Department Chair of Electrical and Electronic Engineering for his suggestions and support in project I would like to thank my family members for providing me inspiration encouragement and strength throughout my master s program I would like to thank my all friends especially Pratik Patel Manan Shah Dhrumil Jariwala Chandrasekhar
27. ion these fans work on particular algorithms to run at variable speed If the temperature is too high then it runs at maximum speed Temperature sensor senses the temperature and speed of fan increases with the rise in temperature Therefore in this way fan does not run on maximum speed unless required to save power 10 Figure 4 1 shows block diagram of the fan control system Block diagram shows microcontroller ATmega168 takes analog input from temperature sensor gives output on LCD display unit and controls motor 4 1 Configuring ADC in ATmegal 68 Temperature sensor senses the room temperature and generates analog output voltage which is proportional to the temperature sensed This voltage can be given to any of ADC pin from ADCO to ADC5 PC0 PC5 of ATmegal68 ADMUX register value defines which ADC pin is used as input Table 4 1 shows ADC input channel selection by MUX 3 0 bits 2 Temperature Sensor C Analog Input PWM Output Motor Microcontroller ATmega168 NY Output LCD Display Unit Figure 4 1 Block Diagram of Fan Control System Single Ended MUX 3 0 Input 0000 ADCO 0001 ADC1 0010 ADC2 0011 ADC3 0100 ADC4 0101 ADC5 Table 4 1 Input Channel Selections for ADC 2 27 28 ADCSRA is an 8 bit ADC control and status register which controls ADC enable ADCEN ADC start conversion bit ADSC and ADC prescaler
28. ls flow of the program make Programmer writes make file which includes lists and controls about how the design is going to build 33 Makefile is very powerful file which usually have information regarding type of microcontroller connection of the programming device type of programming device source coding files and degree of optimization Makefile tells compiler what files to compile and link them if there are more what commands to run and what output file to create 15 14 GCCFLAGS g 0s Wall mmcu atmegal68 LINKFLAGS W1 u vfprintf Iprintf_flt wl u vfscanf Iscanf_flt Im AVRDUDEFLAGS c avr109 p m168 b 115200 P COM5 LINKOBJECTS microcontroller delay o microcontroller lcd o microcontroller uart o ali project_code upload project_code hex project_code c make C microcontroller avr gcc GCCFLAGS LINKFLAGS o project_code o project_code c LINKOBJECTS avr objcopy j text O ihex project_code o project_code hex project_code ass project_code hex avr objdump S d project_code o gt project_code ass project_code upload project_code hex avrdude AVRDUDEFLAGS U flash w project_code hex a Figure 5 1 Makefile Example Figure 5 1 shows an example of makefile It shows mccu atmega168 in the first line type of microcontroller used Communication port and programmer are defined in third line Other files required for the compilation with the code are linked in 4the line
29. m the ATmegal68 by writing make on the command prompt 37 ga C Windows system3 WH avrdude done Thank you C Users Nayan Pate l Desktop nayan pro ject gt make make CG microcontroller makelil Entering directory C Users Nayan Patel Desktop nayan microcontroller makelil Nothing to be done for all makelil Leaving directory C Users Nayan Patel Desktop nayan microcontroller avr gcc g 0s Wall mmcu atmegai68 W1 u vfprintf lprintf_flt Wl u vufscan f lscanf_flt lm o project_code o project_code c microcontroller delay o microcontroller lcd o microcontroller uart o avr objcopy j text 0 ihex pro ject_code o project_code hex avrdude c avri p mi68 b 115266 P COM1 U flash w project_code hex a Connecting to programmer Found programmer Id FDL v 2 type Software Version 2 No Hardware Version given Programmer supports auto addr increment Programmer supports buffered memory access with buffersize 128 bytes Programmer supports the following devices Device code x35 avrdude AUR device initialized and ready to accept instructions Reading HHHHHHHHHHHHHHHHHHHHHHHHHHRHHHHHHHHHHHHHHHHHHHHHH 160 D Biz avrdude Device signature x1e 466 avrdude NOTE FLASH memory has been specified an erase cycle will be performed To disable this feature specify the D option avrdude erasing chip avrdude reading input file project_code hex
30. n this project PB2 PB3 PB4 PB5 are used for SPI bus and works as slave select SS master out slave in MOSI master in slave out MISO and serial clock SCK respectively This port has internal pull up registers 2 Port C PC5 0 Port C is 7 bit bi directional I O port with internal pull up registers This all pins work as analog to digital converter input pins For other applications PC4 and PC5 can be used for 2 wire serial bus I2C For this PC4 is DC input output data line and PCS is DC clock line 2 PC6 RESET PC6 pin is used as reset when RSTDISBL fuse is not programmed otherwise it works as I O pin This pin is active low reset 2 Port D PD7 0 Port D is an 8 bit bi directional I O port with internal pull up resistors PDO and PD1 are USART input output pins respectively PD2 to PD7 are used to display output on LCD for this project 2 AVcc This is supply voltage for A D converter 2 ARef This is analog reference for ADC 2 2 2 Block Diagram of ATmegal168 en o wm mn mm al wn e e e a 2 S a RESET XTAL 1 2 PD 0 7 PB O 7 PC O 6 ADC 6 7 Figure 2 2 Block Diagram of ATmega168 2 ATmegal68 microcontroller is really flexible to use in embedded control systems This device can be programmed in two ways In system programming through serial peripheral interface SPI or programming via boot loader This boot loader file can be downloaded on chip via any interface 2 2
31. netic field generated by stator and rotor have same frequency so BLDC motors are synchronous motors Figure 3 6 shows transverse section of BLDC motor BLDC motors have mainly two parts stator and rotor Some of the motors consist of hall sensors BLDC fans do not have problems related to sparking wearing of brushes or electromagnetic interference EMI as they use electrical commutation Figure 3 7 shows BLDC fan used for the project 7 8 Stator Windings Hall Sensors Rotor Magnet S Accessory Shaft Driving End of the Shaft Hall Sensor Magnets Figure 3 6 BLDC Motor Transverse Section 7 22 Figure 3 7 BLDC Fan Stator is the stationary part of motor Stator have coil which is placed in the slots around the inner periphery Stator coil windings are two types depending on the back electromotive force they produce trapezoidal and sinusoidal 7 Rotor is the part of motor that rotates Rotor is made of permanent magnet with alternate North N and South S poles over the circular core BLDC fan use permanent magnets so it has lighter rotor than the conventional DC fan that makes them suitable for the cooling fan application in laptop and desktop computers 7 8 Hall sensors detect the rotor position by south and north poles and based on their position exact commutation sequence is determined This commutation sequence is important in rotating BLDC motors as they use electronically controlled commutation 7 3 7
32. ng frequency 24 ATmegal68 have on chip PWM unit which controls the motor for this project The on chip 16 bit timer counter provides modulating square wave 9 12 3 8 Variable Speed Control in BLDC Fan 12V PWM drive signal _ Minimal Heat Dissipatio Figure 3 9 BLDC Fan Speed Control with PWM 8 Figure 3 9 shows BLDC fan speed control using PWM It shows FET Field Effect Transistor is connected in series with the BLDC fan to control supply voltage across it PWM Pulse Width Modulation driving method is used to control that voltage In this method PWM signal is applied to FET and FET controls switching of BLDC fan The speed of the fan is directly proportional with duty cycle of the PWM The PWM 25 frequency is important in controlling motor as high frequency may malfunction the commutation circuit and low may cause the fan oscillate 8 11 26 Chapter 4 DESIGN OF FAN CONTROL SYSTEM This chapter describes how the speed of fan is controlled by PWM output from microcontroller with the change in lab temperature Desktop computers and laptops use CPU fan for the cooling purpose for the microprocessor Without CPU fan microprocessor may overheat and may cause the computer system to fail or malfunction CPU fans are used in order to maintain certain temperature level in the computer system to provide optimum operating range of temperature for all components to work properly To minimize power consumpt
33. nput pin Vrer is selected reference voltage 2 2 4 1 ADC Prescaler For ADC in order to get optimum resolution we require input frequency between 50 to 200 kHz A prescaler takes CPU clock frequency as input and generates ADC clock ADC prescaler is shown in Figure 2 9 Prescaler starts counting and keeps on run mode until ADEN bit is set in ADCSRA register 2 14 ADEN START Reset 7 BIT ADC PRESCALER ADPSO ADPS1 ADPS2 ADC CLOCK SOURCE Figure 2 9 ADC Prescaler 2 While ADEN is set for the first conversion it takes 25 ADC clock cycles and the rest of conversion takes 13 ADC clock cycles Figure 2 10 shows timing diagram for first conversion single conversion and free running conversion 2 Next First Conversion Conwersion 1 1 1 1 Cie Number pal 2 elslklelelelslwlslslslslsalsl lites 3 I I T i 2 Ee ADCH GO Sigrand MSE of Result ADCL E SE LEB ot Aost aa REFS jo aou Ra SZ a WEE MUX and REFS a For First Conversion 15 One Conversion Neat Conversion deeg I I I I oenm 1j 2 2 4 5 ef 7 2 8 nj e ej ty 2 3 weng TL LTL LIL LILILIL LLLLL LELELTL ADSC 1 D j 1 ADIF l l i wn DEU Stee ADCL EE LSB of best ise EE Dag K and REFS MUX and REFS Update b For Single Conversion One Conversion Next Conversion i EH l pen 12 8 E 2 3 4 ADSC GE SE LEE l l ADIF l l wo ZZZ eise Sg A eee MUX and REFS c For Free Running
34. output which is given to motor and controls speed of motor fan Microcontroller continuously displays temperature of lab on LCD 8 11 12 32 Chapter 5 MICROCONTROLLER PROGRAMMING I used general purpose programming language C for the implementation of this project One main advantage of C over assembly language is that you can easily switch between microcontrollers Assembly language is specific for particularly that microcontroller so if you happen to change microcontroller then you have to start the code from beginning I used WinAVR compiler for this project to compile the project code written in language C 5 1 WinAVR WinAVR is not just one tool it contains many tools like avr gcc compiler avr gdb debugger avrdude the programming interface avr libc library and many more WinAVR pronounced whenever is a suite of executable open source software development tools for the Atmel AVR series of RISC microcontrollers hosted on the Windows platform It includes the GNU GCC compiler for C and C 13 14 5 1 1 Installing WinAVR WinAVR is an open source development tools that can be downloaded free from http winavr sourceforge net After downloading it run the file for installation It will download to C WinAVR as default In this folder there is a text file called WinAVR user manual it contains information regarding how to use 13 14 5 1 2 Makefiles A makefile is a text file which contro
35. rature Monitoring and Control Elsevier Science amp Technology Books pp 1 7 pp 129 144 September 2002 2 Atmel Corporation 8 bit Microcontroller with 8K Bytes In System Programmable Flash pp 1 6 109 137 245 260 September 2007 3 National Semiconductor Corporation LM34 Precision Fahrenheit Temperature Sensors pp 1 6 November 2000 4 STMicroelectronics L78xxC L78xxC Positive voltage regulators pp 1 7 August 2007 5 HITACHI HD44780U Dot Matrix Liquid Crystal Display Controller Driver pp 1 9 pp 22 29 1998 6 Fairchild Semiconductor 2N7000 N Channel Enhancement Mode Field Effect Transistor November 1995 7 Microchip Brushless DC BLDC Motor Fundamentals pp 1 18 July 2003 8 T C Lun Microcontroller for Variable Speed BLDC Fan Control System Freescale Semiconductor 9 Michael Barr Introduction to Pulse Width Modulation PWM July 2003 Retrieved on November 8 2010 From the World Wide Web http www oreillynet com pub a network synd 2003 07 02 pwm html page last amp x maxdepth 0 10 Rodney H G Tan Y H Goh Y Q Wong and V H Mok Energy Efficient Cooling Fan for PC Chassis IEEE conference on Innovative Technologies in Intelligent Systems and Industrial Applications July 2009 11 STMicroelectronics AN2680 Application Note Fan speed controller based on STDS75 or STLM75 digital temperature sensor and ST72651AR6 MCU
36. rce used by timer counter CS 0 bit is set to 1 so clock used with prescaler divider 1 for this project 2 2 4 Analog to Digital Converter ADC CONVERSION COMPLETE IRQ BS DATA BUS i ADC MULTIPLEXER ADC DATA REGISTERA SELECT ADMUX ADCSAA ADCHIADCL D WOH CONVERSION LOGIC HOLD 10 BIT DAC Se avcc CHAN NELSELECTON INTERNAL 1 1V E REFERENCE wel GND BANDGAP REFERENCE pyi cg avos 00 ARLENE sige SC wa sol SSC Figure 2 8 Block Diagram of ADC Atmegal168 2 13 ATmegal68 Analog to Digital Converter ADC uses 10 bit successive approximation method to convert 8 single ended voltage inputs from the pins of Port C via 8 channel analog multiplexer Figure 2 8 shows block diagram of ADC 2 The ADC takes analog input voltage on pins of Port C and converts it in 10 bit digital value presented as ADCH and ADCL in ADC data registers The minimum value represents GND and maximum value represents the voltage on the AREF pin minus 1 LSB The data in registers is right adjusted so ADCL must be read first The reference voltage for ADC can be selected as internal 1 1 V Avcc or external AREF pin that describes the conversion range for the ADC For this project AREF external reference voltage pin is used 2 For single ended conversion the result found in ADC registers ADCL ADCH is described by following equation Vy 1024 REF ADC Where Vw is voltage on the selected i
37. uency on OCIx can be calculated by the following equation 2 f Fon LO OCnxPWM W 1 nas TOP 11 Where N is a variable represents prescaler divider 1 8 64 256 or 1024 2 By assigning TOP value to OCRIx will result in a constant high or low output 2 2 3 3 Register Description 2 3 3 1 TCCR1A Timer Counter 1 Control Register A Bit 7 6 5 3 2 1 D 0x80 COM1A1 COM1A0 COM1B1 COM1B0 WGM WGM10 TCCRIA Read Write RIN RW RW RW R R RW RIN Initial Value D 0 0 0 0 D d D Figure 2 6 Timer Counter 1 Control Register A 2 Bit 7 6 COM1A1 0 Compare Output Mode for Channel A Bit 5 4 COM1B1 0 Compare Output Mode for Channel B For my project both COM1B1 bits are written to 1 so it will set OC1A OC1B on compare match DDR Data Direction Register must be set to enable pin OCIA or OCIB as output 2 Bit 1 0 WGM11 0 Waveform Generation Mode The combination of WGM13 WGM12 WGM11 and WGM10 from both TCCRIA and TCCRIB will define the counting sequence of counter what kind of waveform generation used and TOP maximum counter value These all bits are set as 1 2 2 3 3 2 TCCR1B Timer Counter Control Register B Bit 7 6 5 4 3 2 1 D 0x81 ICNC1 ICES1 wow CS12 csit csi0 TCCR1B Read Write RIN RW R RW RW RW RW RW initial Value D o H 0 H 0 o D Figure 2 7 Timer Counter Control Register B 2 12 Bit 2 0 CS12 0 Clock Select These three bits will select the clock sou
38. ure and control the motor according to the temperature 1 4 Organization of Report Chapter two of the report explains architecture of ATmegal68 microcontroller It describes all pins and architectural block diagram of ATmega168 It also describes 16 bit timer counter module with PWM and analog do digital converter and its registers Chapter three contains information about different components used for the project It includes brief description of temperature sensor crystal oscillator voltage regulator LCD MOSFET brushless DC motor and PWM Chapter four explains about how to configure ADC in ATmegal68 PWM initialization implementation of fan control system It includes block diagram circuit diagram and flow chart for this project Chapter five provides information on WinAVR compiler makefiles and programmer s notepad It includes explanation about command line program AVRDUDE It contains programming of ATmega168 and results for this project Chapter six contains conclusion and future work Chapter 2 ATMEGA168 MICROCONTROLLER ARCHITECTURE ATmegal68 is an 8 bit reduced instruction set computing RISC microcontroller developed by Atmel Corporation It has 32 8 bit general purpose registers and 131 powerful instructions ATmegal68 has 16K bytes non volatile self programmable flash memory 1K bytes of static random access memory SRAM and 512 bytes of electrically erasable programmable read only memory EEPROM In its peripheral fe
Download Pdf Manuals
Related Search