Full Report in PDF format - ECE
Contents
1. from Transfer Then Hyper Terminal should be disconnected Data analysis If matlabcommand m is not yet available copy it from the Appendix E above Save result txt and mathlabcommand m on the same directory Run the matlabcommand m in Matlab and change the Matlab working directory 1f necessary A figure with the X axis s Y axis s and Z axis s data is shown Five image files called xaxis jpg yaxis jpg zaxis jpg result jpg and scalarguan jpg are automatically saved into the same directory of the two other files 45 Appendix H Picture Remote end s hardware 4 gom OF su gt drav e et DODGE Er Ce CC MU OES OE EF 3 g r OGC O OG O00 00 y DOOODE DODO EF 6 0 6 0 NG OO000000000000000000000 1 U U U H 46 Base station s hardware 47 System Overview 48 Appendix I Bibliography Mega32 datasheet http www atmel com dyn resources prod_documents doc2503 pdf Radiometrix SP2 433 16 radio packet controller http Www radiometrix co uk dsheets sp2 pdf Radiometrix SP2 433 16 radio packet controller evaluation kit http Www radiometrix co uk dsheets sp2ek pdf Mega32 prototype board http homepage sunrise ch mysunrise pfleury avr starterkit html Max233 driver receiver http pdfserv maxim ic com en ds MAX220 MAX249 pdf Analog Device ADXL311 2g dual axis accelerometer http www ana2. s outputs are neglected and the practical values are derived Ing X axis Y axis Z axis 2 OxA5 1 0x95 0 0x85 1 0x75 2 0x65 Radio Packet Controller Radiometrix SP2 433 16 radio packet controller is chosen for the project SP2 is a highly intelligent transceiver module at 160kbps half duplex It is operational at 5V and is direct interface to 5V CMOS logic It has a reliable 50m in door and 200m outdoor range SP2 includes two modules internally One is UHF module which is responsible to transmit and receive data The other is space port controller which is responsible to control data and to interface with external microcontroller Operational method inside SP2 is user transparent SP2 works either in transmitter mode or receiver mode and it uses a handshaking mechanism to prevent data loss during transmission In the remote end s hardware four LEDs are used to indicate states of the SP2 e Green LED transmitter enabled Pin5 TXSelect Red LED receiver enabled Pin4 RXSelect e Orange LED valid preamble detected Pin10 Signal e Yellow LED valid packet received Pin13 RXR Preamble allows data slicer in receiver to establish a correcting slicing point After the receiver has settled the SP2 identify and phase lock onto the incoming data A 4 whip wave whip of 433MHz is mounted onto the prototype board to boost its signal strength and it does give a much longer range a
3. 10 SP2 reset 1 SP2 ready if time0 100 begin time0 0 reset timer X axis if ADC doneconversion 1 ADC_doneconversion 0 ADC X read ADC ADC Xsel Y axis if ADC doneconversion 1 ADC doneconversion 0 ADC Y read ADC ADC Ysel Z axis if ADC doneconversion 1 ADC_doneconversion 0 ADC Z read ADC ADC Zsel Task2 ADC_X ADC_Y TX_byte_count 0 rx byte pos 0 MCU to SP2 buffer 0 TX control byte TX byte count while TX byte count lt 4 testing hardcode sequence of data MCU to SP2 buffer TX byte count 0x55 if TX byte count 1 CU to SP2 buffer TX byte count 0x70 else if TX byte count 2 CU to SP2 buffer TX byte count 0x75 else if TX byte count 3 CU to SP2 buffer TX byte count 0x78 if TX byte count 1 CU to SP2 buffer TX byte count ADC X else if TX byte count 2 CU to SP2 buffer TX byte count ADC Y else if TX byte count 3 CU to SP2 buffer TX byte count ADC Z 3l Show Y axis on remote end s hardware PORTB ADC_Y TX byte count assert TXR low to initiate transfer to SP2 amp make sure RXA is high TXR 0 MCUCR 0x0A falling edge for request accept end end 32 Appendix D Base station microcontroller s Code k k k kok k kok k k K K k K K K Kk K KOK K K KOK Ck kck ck kck ck KKK KKK KOK k kk Project Complete Receiver Versio
4. 2EVIIKLU GND GND PC SCL PC1 SDA PC2 TCK PC3 TMS PC4 TDO PCS TDI PC6 TOSC1 PC TOSC2 FF PD RXD PD1 TXD PD2 INT PD3 INT1 PD4 0C1B PD570C1A PD6 1CP PD7 0C2 11 31 Radiometrix SP2 433 16 22 GND 81 Yeo 28 D3 19 D2 18 DL 17 Da 16 Reset 15 TXR 14 TXA 13 RXR 12 RXA uo ano ul S KWBZKT 8 1 microfarad 158 ohms Cornell University MEng Project ECE 2 picofarad 100 kilo ohms Base station hardware Rev 1 0 Mong Kim Fung 127472083 Page 171 24 Appendix C Remote end microcontroller s Code KOK KK kok k kok k k K k I k K K K K K KOK K KOK K KOK KOK KOK KOK OK KOK k k K Project Complete Transmitter Version 1 2 Date 12 05 2003 Author Wong Kim Fung Company Cornell University Ithaca NY USA Comments Program is complete and functions Chip type ATmega32 Program type Application Clock frequency 16 000000 MHz Memory model Small External SRAM size 0 Data Stack size 24512 KKKKKK KKK KKK KKK Ck K K Ck KKK k kc K KKK KKK KKK KKK KKK KKK LEDs indicator Green transmitter enabled Red receiver enabled Orange preamble detected Yellow valid packet received include lt Mega32 h gt include lt string h gt include lt stdio h gt include lt stdlib h gt define begin define end Accelerometer parameters define ADC_VREF_TY
5. Axis labels and titles are shown on each graph and each axis has a unique color representing itself Since this project is designed to be simple and user friendly A color images of the graphs are saved automatically as xaxis jpg yaxis jpg zaxis jpg result jpg scalarguan jpg in the same folder of the Matlab command file 17 5 Test Results Demonstration has been given to Dr Land at a teaching lab in Corson Hall The system functions well and data collected are good The design has been proved to be successful During demonstration the system was tested with a range of 20 plus meters and the base station can receive data without any difficulty The specification of radio packet controller claims to be 50 meters range in building Because of this impressive range the project can be greatly applied into future application or design The accelerometers are suitable for the designed application From various tests a person can hardly reach an acceleration of 2g although a 2g motion is possible with vigorous movements Z axis of the system is positive pointing upward and negative pointing downward Gravitational force on earth is 1g and the tested value of Z axis while being idle is proved to be consistent with this theoretical value Notice that both X and Y axes have value of Og when they are idle but Z axis has value of 1g when it is idle Two samples of test results are documented in this report The first test result is shown below a
6. INTO void ext int0 void begin unsigned char temp TX data PORTB 0xF0 debugging switch TX state case TXA regaccept lsb begin PORTB 0x10 debugging set data lines to output amp place data on the data lines DDRC DDRC Ox0F PORTC PORTC amp 0xFO MCU to SP2 buffer TX byte pos amp Ox0F TXR 1 tell SP2 that data is present MCUCR 0x03 rising edge for data read TX state TXA dataread lab Next state end break 28 case TXA dataread 1sb begin PORTB 0x20 debugging wait for SP2 to set TXA to high to tell MCU that data has been read TXR 0 transfer request by MCU MCUCR 0x02 falling edge for request accept TX state TXA regaccept msb end break case TXA regaccept msb begin PORTB 0x40 debugging shift the MS nibble to LS and send to data lines temp TX data MCU to SP2 buffer TX byte pos amp 0xF0 gt gt 4 PORTC PORTC amp OxF0 temp TX data TX byte pos increment transmit buffer position TXR 1 data present MCUCR 0x03 rising edge for data read TX state TXA dataread msb end break case TXA dataread msb begin PORTB 0x80 debugging if TX byte pos TX byte count TXR 0 transfer request MCUCR 0x02 falling edge for request accept else DDRC 0xF0 done TX set data lines to input MCUCR 0x0A enable EXT INT1 on falling edge TX state TXA reqaccept lsb end break
7. byte 0 amp amp RX byte count 0 RX enable data are valid sent to USART QxA2 0x62 0x9D Ox5D 0xA5 0x65 e and dump data to PC reguest accept Appendix E Matlab Code Version Date December 1 2003 This matlab file is used to display the data collected by the acceleration reading device data percent load result txt data g data percent 2 100 row size col size size data percent X data g l end 1 put 1st column of data g in X Y data_g 1 end 2 put 2nd column of data gin Y Z data_g 1 end 3 put 3rd column of data g in Z calculating total scalar quantity of 3 axes for i l row size scalar quan 1 sqrt X 1 2 Y i 2 Z i 2 end t l row_size subplot 2 2 1 plot t X bo grid on title Acceleration Xaxis xlabel samples 10Hz ylabel acceleration g Automatically save the figure into the current work directory as xaxis jpg with best resuoltion print djpeg100 xaxis jpg figure subplot 2 2 2 plot t Y gp grid on utle Acceleration Yaxis xlabel samples 10Hz ylabel acceleration g print djpeg100 yaxis jpg figure subplot 2 2 3 plot t Z r grid on utle Acceleration Zaxis xlabel samples 10Hz 38 ylabel acceleration g print djpeg100 zaxis jpg figure subplot 2 2 4 plot data g legend X axis Y axis Z axis title Acceleration measurement 3a
8. changed throughout the development revisions on the design were constantly made In the following four major components of the system are introduced 3 1 Microcontroller Atmel AVR microcontroller is chosen for this project because I am relatively familiar with it It has been used in ECE476 Microcontroller class which I had taken during spring semester and general technical support is available from Dr Land or various websites It is a good fit for the project as it includes eight built in analog to digital conversion channels built in USART two external interrupts and four bi directional ports which are just enough for project development and debugging purpose 3 2 Wireless Connection Initial design was to apply Bluetooth technology instead of using radio packet controller SP2 After much research had been done the cost of a pair of Bluetooth module was from 300 to 400 The worse fact is that most modules can only support point to point It will be a while before the next generation point to multipoint OEM modules are available After discussing this with Dr Land we omitted the choice of Bluetooth technology and chose to use radio packet controller At a cost of 198 the SP2 does give some advantages over Bluetooth modules that are available First and most important multiple SP2 can form a small personal network and each packet can include the source and destination address ID Second SP2 includes handshake mechanism to prev
9. hile ADCSR amp 0x10 0 DCSR 0x10 DC_doneconversion 1 return ADCH 27 Testing show one axis working alone void Taskl unsigned char ADC value begin if ADC value lt 0xA2 amp amp ADC value gt 0x92 PORTB 0x0f else if ADC value lt 0x92 amp amp ADC value gt 0x82 PORTB 0x55 else if ADC value 0x82 PORTB 0x00 else if ADC value lt 0x82 amp amp ADC value gt 0x72 PORTB 0xaa else if ADC value lt 0x72 amp amp ADC value gt 0x62 PORTB 0xf0 else PORTB 0xff end ar Testing show two axes working together void Task2 unsigned char ADC vl unsigned char ADC v2 begin unsigned char LED LED_X LED_Y if ADC_v1 lt 0xA2 amp amp ADC_v1 gt 0x92 JED X 0b11000000 else if ADC v1 0x92 amp amp ADC v1 gt 0x82 ED X 0b10000000 else if ADC v1 lt 0x82 amp amp ADC v1 gt 0x72 ED X 0b01000000 else if ADC vl lt 0x72 amp amp ADC vl gt 0x62 JED X 0b00000000 else if ADC v1 0x82 ED X 0b11000001 if ADC v2 lt 0x9D amp amp ADC v2 gt 0x8D ED Y 0b00110000 else if ADC v2 lt 0x8D amp amp ADC v2 gt 0x7D ED Y 0b00100000 else if ADC v2 lt 0x7D amp amp ADC v2 gt 0x6D ED Y 0b00010000 else if ADC v2 lt 0x6D amp amp ADC v2 gt 0x5D ED Y 0b00000000 else if ADC v2 0x7D ED Y 0b00110010 LED LED X LED Y PORTB LED end detect TXA MCU to SP2 transfer interrupt EXT
10. signals from accelerometers converting signals into digital count by built in ADC arranging data into packet and sending the packet to the base station s hardware Base station s hardware is responsible in receiving packet rearranging the received data in percentage and transmitting the rearranged data to a computer via USART Finally data is analyzed in some graphs 2 2 System Requirements A simple to use and maintenance free system is the priority of this design A nearly plug and play system is designed with minimum user s operational steps After discussing with Dr Land system requirements are as following e Fora given tight budget cost needs to be kept low e The device should be fairly compact since it would be carried on a human s body e Range of the radio frequency connection should be highly stable up 20m e The system should be expandable with multiple clients if necessary e Acceleration readings should be constantly updated at 10Hz e A graphical interpretation should be available on the received readings e No radio interference is allowed on other instruments 3 Range of solutions The initial project proposal is slightly different from what the deliverable is at the end of implementation Various components of the initial design have been replaced This could be a reason of better fit or just happened that the wanted components were unavailable at the time of implementation As some of the hardware had been
11. time0 end Repacketize received data into percentrage of 2g and then print the new buffer in to PC void Repack Sendmsg void begin int temp value RS head 0 RS tail 4 PORTB 0x70 reorganized the SP2 packet into another buffer this is for user readability on the hyperterminal RS buffer RS head SP2 to MCU buffer 0 while RS head lt RS tail if RS head 1 temp value int SP2 to MCU buffer RS head 130 100 else if RS head 2 temp value int SP2 to MCU buffer RS head 125 100 else if RS head 3 temp value int SP2 to MCU buffer RS head 133 100 RS buffer RS head temp value 32 printf S4d RS_buffer RS_head prrintf RS_head printf NnNEet RS_head 0 end 35 detect RXR SP2 to MCU transfer interrupt EXT_INT1 void ext intl void begin unsigned char temp_RX_data switch RX_state case RXR tranreq lsb begin PORTB 0x01 RXA 0 Step2 MCU pulls RX accept low CUCR 0x0C rising edge for data present RX state RXR datapresent lsb Next state end break case RXR datapresent lsb begin PORTB 0x02 SP2 turns on bus drivers places LS nibble onto data lines and set RX reguest to high SP2_to_MCU_buffer RX_byte_pos PINC amp Ox0F RXA 1 data read MCUCR 0x08 falling edge for transfer request RX state RXR tranreg msb end break case RXR tranreg msb begin PORTB
12. 0 140 160 samples 10Hz A figure including the X Y and Z axes is shown 43 Acceleration measurement scalar quantity of 3axes 1 8 T T T T T C o o T acceleration g T 0 2r T d 0 l l l l l 0 20 40 60 80 100 samples 10Hz Scalar quantity of X Y and Z axes is shown 44 120 140 160 180 Appendix G User s Manual System set up Plug in a serial cable with base station s DB9 connector and a computer Make sure coml is available for Hyper Terminal If not go to Device Manager of Windows OS to change the com port Open up a Hyper Terminal with 9600 baud rate stop bits no parity and no flow control Connection s name is up to user s preference Go to File on menu and Properties and select Settings Click ASCII setup choose Append line feeds to incoming line ends from ASCII Receiving Put 9V batteries into the base station s and remote end s battery holders Make sure the polarities are correct Data collecting Make connection to the Hyper Terminal and go to Transfer and Capture Text on menu Open the file named result txt and make sure it is empty Press start on the Capture Text window to start collecting data When data is being collected it is shown in three columns When enough data are collected click stop from Capture Text
13. 0x04 RXA 0 request accept by MCU MCUCR 0x0C rising edge for data read RX state RXR datapresent msb end break case RXR datapresent msb begin PORTB 0x08 shift the MS nibble to lower read data lines temp RX data PINC SP2 to MCU buffer RX byte pos temp RX data lt lt 4 SP2 to MCU buffer RX byte pos RX byte post t if Getting control byte get to know how many bytes the packet ar Getting_control_byte 0 RX_control_byte SP2_to_MCU_buffer 0 zero the bit6 7 to get the exact count RX byte count SP2 to MCU buffer 0 amp Ox3F else if RX byte count gt 0 RX byte count 36 done receiving a packet if Getting control byte 1 done if statements make sure the otherwise data wouldn t be if SP2 to MCU buffer 1 lt amp amp SP2 to MCU buffer 1 amp amp SP2 to MCU buffer 2 lt amp amp SP2 to MCU buffer 2 amp amp SP2 to MCU buffer 3 amp amp SP2 to MCU buffer 3 gt repacketiz Repack Sendmsg PORTB SP2 to MCU buffer 2 MCUCR 0x08 falling edge for transfer RXA 1 RX state RXR tranreg lsb end break end void main void begin initialize while 1 if time0 10 SP2_reset 1 if time0 500 begin time0 0 reset timer RX byte count 0 RX byte pos 0 UCSRB 0x08 transmitter enable CUCR 0x08 end end 37 falling edge for request Getting control
14. AN ACCELERATION MEASURING SYSTEM VIA RADIO FREQUENCY COMMUNICATION A Design Project Report Presented to the Engineering Division of the Graduate School Of Cornell University In Partial Fulfillment of the Requirements for the Degree of Master of Engineering Electrical by Wong Kim Fung Project Advisor Dr Bruce Land Degree Date January 2004 Abstract Master of Electrical Engineering Program Cornell University Design Project Report Project Title An Acceleration Measuring System via Radio Frequency Communication Author Wong Kim Fung Abstract This project is designed to explore the possibility of building a compact acceleration measuring device and applying it in a typical middle high school science class Such an interesting interactive device could to be used to improve the traditional classroom environment Students can carry the device on their bodies and see how fast they move and ideally it is hoped to help them become more interested in learning simple physics The project s design is based on a pair of microcontrollers Accelerometer s sensors are used and data are transmitted through radio frequency and serial communication RS232 Readings of the accelerometer s outputs are updated ten times a second and data will be shown in graphical interpretation after measurement is taken The designed goal of this project is to provide a simple to use and reliable device that can record the acceleration with good tim
15. PE 0x00 define ADC_Xsel 0x00 define ADC_Ysel 0x01 define ADC_Zsel 0x02 define ADC pos2g 0xA0 define ADC_poslg 0x90 define ADC Og 0x80 define ADC neglg 0x70 define ADC neg2g 0x60 define Accelerometer range 2 SP2 reset define SP2 reset PORTD 7 MCU SP2 transfer signals define TXR PORTC 6 TXA PIND 2 define RXA PORTC 5 RXR PIND 3 SP2 states define TXA regaccept lsb define TXA dataread Lab define RXR tranreg Lab define RXR datapresent lsb define TXA regaccept msb define TXA dataread msb define RXR tranreq msb define RXR datapresent msb CO Jo DG O ha LES 2 Global variables Accelerometer variables unsigned char ADC_X unsigned char ADC_Y unsigned char ADC_Z unsigned char ADC_doneconversion Control byte for SP2 transmitter nsigned char TX_control_byte Counter for transmitting bytes nsigned char TX_byte_count Position for transmitting bytes nsigned char TX_byte_pos Buffer for data packet nsigned char MCU_to_SP2_buffer 10 Cui SSG TRE PS S I Control byte for SP2 receiver unsigned char RX_control_byte Counter for receiving bytes unsigned char RX byte count Position for receiving bytes unsigned char RX byte pos Buffer for data packet junk unsigned char SP2 to MCU buffer 2 flag for getting Control byte bit Getting control byte unsigned char TX state unsigned char RX state interrupt v
16. acceleration on three axes it could also keep track on how the device has moved Also a smaller board could be built specially for the remote end s hardware Although the final remote end s hardware is not bulky the device would fit into more applicable place if it was smaller It could truly be used in a grade school s science class if hardware is properly placed into an enclosure 20 7 Acknowledgements This project would not be done without Dr Bruce Land s support and guidance I would like to thank him for soldering the tiny accelerometers on to the prototype boards And I owe him an apology for hurting his finger when drilling a hole on the board I also would like to thank my family and girlfriend for supporting me I have gained a lot of encouragement from them during my studies They have been well supporting and respecting my decision on the Mastering of Engineering studies at Cornell University 21 Appendix A Cost Item Item description Quantity Company Price 1 Radiometrix SP2 433 160 Lemos International 198 radio packet controller 2 3 Solderable perf board 0 1 grid 4 5 Pushbuttons 4 1 7 4 55V Voltage detector TL7757 1 44 17 2 ADSL311 2g accelerometer We Analog Devices Sample 18 MAX233 media driver 1 Maxim IC Sample Total 252 63 Note Miscellaneous parts such as Mega32 16MHz crystals resistor capacitors and wires etc are negligible as they are acquir
17. ariables unsigned char reload unsigned int time0 void initialize void begin ADC input X Y Z axes PAO X PAl Y PA2 Z DDRA 0xF8 testing DDRB 0xFF PORTB 0xFF MCU to SP2 interface Bit6 TXR Bit5 RXA DDRC 0xF0 PORTC 0xF0 Bit2 TXA Bit3 RXR Bit7 SP2 reset DDRD 0xF3 Timer Counter 0 initialization Clock source System Clock time0 0 reload 256 250 TCCR0 0x03 clk 64 26 end TCNTO reload Timer Counter0 Overflow Interrupt Enable TIMSK 0x01 ADC initialization ADMUX ADC_VREF_TYPE 0x20 Left adjust result ADCSR 0x87 ADC doneconversion 1 SP2 initialization SP2 reset 0 TXR 1 PORTC 6 out RXA 1 PORTC 5 out TX control byte 0x04 RX byte count 0 RX byte pos 0 Getting control byte 1 TX state 1 RX state 3 GICR 0xC0 External interrupts 0 1 enabled MCUCR 0x0A Falling edge generates interrupt Global enable interrupts fasm sei Timer 0 overflow interrupt service routine interrupt TIMO OVF void timer0 overflow void begin end reload to force lms overflow TCNTO reload time0 Read the AD conversion result unsigned char read ADC unsigned char ADC input begin end ADMUX ADC VREF TYPE 0x20 ADMUX ADC input Start the ADC conversion ADSC bit6 returns to zero after conversion ADCSR 0x40 ADCSR 0xc7 W A A Wait for the ADC conversion to complete
18. collision avoidance mechanism to prevent data loss during transmission It can also be customized to include source and designation address in the packet However the cost would need to be lowered for production use The planning and implementation of this project have gone well and smoothly Planning was carefully thought through from the beginning of design and it was worth the time since a careful plan saves a lot development time The final deliverable is fairly compact and solid Data transmission between the pair of radio packet controllers is robust Accuracy of accelerometers is acceptable Overall the system functions well and works as desired il Table of Contents An Acceleration Measuring System via Radio Frequency Communication PRS URAC EE i Executive SUMMARY cis ba Oe CON TEMO e BEP oo Ee ii T Introductioh ee s ertet erba e Reto dd eie Rc vus ERR 1 2 Design Problem and System Reouirementz YY Y Y Y Y enn 2 Dee EE 2 2 2 System Ree 2 3 Range of solutions occorre ty DL YL NW YA GYW y 3 3 1 Microcontrollers SANS 3 3 2 Wireless Connection i ae ea O y CR A GY dn 3 3 3 ACCElErOMeter uyu ua uu deco Sadek yy LY EN VP c ssa PD Se Vaden es ia tes 4 STEE 4 4 Design and Implementaton 000000000 5 4 1 Remote end hardware z sess ds nes A XY Ye ERR RA yeas AA Leo ey wn FERA ERR Nee 5 AD Base station harde ss 11 4 3 r d mud y e Opt Node edk pea RNK kasy ma 13 AA E 3 1656002 ccs Ne 17 5 DESC Results kN 18 6 Co
19. connected with pin 2 of Max233 RXD of microcontroller is not necessary in this project since the data always goes into one direction to computer There was a problem encountered when soldering the DB9 connector onto the prototype board Its pin would not fit in either 0 1 grid board or the 2mm grid board However with help from Dr Land it is fitted onto the board by drilling bigger holes 12 4 3 Embedded program There are two embedded application in the system The program at the remote end s microcontroller is responsible to collect data from accelerometers and to send the data in packet through a radio packet controller The program at the base station s microcontroller is responsible to receive data through radio packet controller and to process packet into a meaningful data format Then reorganized packet is sent through a USART to a computer for graphical analysis Here the remote end s program is explained in detail e interrupt TIMO OVF void timer0_overflow void Since the system is required to collect data in 10Hz an interrupt service routine ISR serves the best by providing an accurate time interval for operation Timer Counter 0 is chosen and ISR occurs every 100 millisecond A 100 millisecond interval is chosen so that people normally would not notice significant data delay Moreover a 50ms interval had been tested on the system and it worked e unsigned char read ADC unsigned char ADC input This func
20. e resolution Report Approved by Project Advisor Date Executive Summary This Master of Electrical and Computer Engineering project is designed to measure acceleration through a simple microcontroller based system It explores the possibility of performing a simple interactive experiment in a science class to help students in learning basic physics This system should be easy to use by any grade teacher with a simple user manual Two dual axis accelerometers are arranged to form a tri axis accelerometer and outputs are sent to an Atmel Mega32 microcontroller MCU The accelerometer s outputs are analog They are converted into digital counts by the built in MCU analog to digital converters The radio connection is established by a pair of radio packet controllers SP2 from Radiometrix For both remote end s hardware and base station s hardware radio packet controllers are connected to MCUs Acceleration readings are sent from the remote end s radio packet controller to the base station s radio packet controller After performing some mathematics on the receiving data the acceleration readings in digital count are converted into percentage and they are sent through a serial communication to a computer Then Matlab is used to display the data into a graphical interpretation This system functions as a point to point system but the SP2s are capable of being applied as a point to multipoint system The SP2 has the handshaking and
21. ed from the lab 22 Appendix B Schematics A 5v s 8 Vdd STL Ka 18 a BIAS A U ADXL311 R2 cnn 3 Paa anca PAL ADC1 4 NC PA2 ADC2 PA3 ADC3 PA47ADC4 PC SCL PC1 SDA A 5v PC2 TCK TA PAS ADCS M Ci 18 vdd Pe anc PC4 TDO PCS TDI PC6 TOSC1 PC7 TOSC2 PDA RXD PD1 TXD PD2 INTO PD3 INTL PD4 0C1B PD5 0C1A PD6 1CP PD7 0C2 ST 1 IL Pa7 ADC7 BIAS a PBa Ta ADXL 311 PBL TL R2 onn 3 PB2 AING PB3 AINL PB4 SS PB5 MOSI PB6 MISO PB7 SCK RESET XTALI XTaL2 AREF AVCC cEUD3WLU GND GND 11 31 433MHz antenna RF GND 1 Antenna 2 RF GND 3 RX Select 4 TX Select 5 2 Green K E GND 6 Radiometrix SP2 433 16 i TXD AF 7 oran e NC 8 NC 9 2 Yellow Signal 18 8 1 microfarad 150 ohms Cornell University MEng Project ECE 2 picofarad 200 kilo ohms 188 kilo ohms Remote end hardware Wong Kim Fung Rev 1 0 Page 1 1 187472003 23 2 R1 Green VV E GND 6 gt u lt fa NP m d a w GA 2 o To ES PA ADC PALZADC1 PA27ADC2 PA3 ADC3 PA4 ADC4 PAS ADCS PA67ADC6 PA7 ADC7 PB T PB1 T1 PB27A NG w Ro M M lw z ble jp jo KO 00 N os Jo o 433MHz antenna RF GND 1 Antenna 2 RF GND 3 RX Select 4 TX Select 5 TXD AF i PB3 AINI PB4 SS PBS MOSI PB6 MISO PB SCK RESET XTALI xTAL2 AREF AVCC w w
22. ences between the two are the USART and accelerometers There is no accelerometer connected with base station s hardware since its purpose is used to receive and process data For the USART PD 1 is used to transmit data serially to the serial communication hardware Please refer to section 4 1 for detail on microcontroller Radio Packet Controller The connection of SP2 in both the base station s hardware and the remote end s hardware are identical Please refer to section 4 1 for detail on SP2 Serial Communication Serial communication RS232 transmits data from microcontroller to computer s Hyper Terminal The USART of base station has baud rate of 9600bps one stop bits no parity bit and data frame is 8 bit The RS232 is negative logic which means that a 1 is negative voltage and a 0 is positive voltage A converter is needed for TXD and RXD and Max233 is chosen because of its internal capacitors Max232 is a popular choice but four external capacitors seem too much for the design and Max233 functions just as well as it 11 A female DB9 connector is soldered with Max233 media driver Pin 5 T1Out of Max233 is connected with pin 2 Receive data of DB9 Pin 5 Signal ground of DB9 connector is connected with ground bus of prototype board Then a serial cable is connected with both DB9 connector and computer together Since USART protocol is used for the serial communication PD1 of microcontroller which is TXD is
23. end detect RXR SP2 to MCU transfer interrupt EXT INT1 void ext intl void begin Switch RX state case RXR tranreg lsb begin PORTB 0x01 debugging RXA 0 Step2 MCU pulls RX accept low 29 MCUCR 0x0C rising edge for data present RX_state RXR_datapresent_lsb Next state end break case RXR datapresent lsb begin PORTB 0x02 debugging SP2 turns on bus drivers places LS nibble onto data lines and set RX request to high SP2 to MCU buffer 0 PINC amp Ox0F RXA 1 data read MCUCR 0x08 falling edge for transfer request RX state RXR tranreg msb end break case RXR tranreg msb begin PORTB 0x04 debugging RXA 0 request accept by MCU MCUCR 0x0C rising edge for data read RX state RXR datapresent msb end break case RXR datapresent msb begin PORTB 0x08 debugging shift the MS nibble to lower read data lines SP2 to MCU buffer 0 PINC lt lt 4 SP2 to MCU buffer 0 MCUCR 0x08 falling edge for transfer request if Getting_control_byte Getting_control_byte 0 RX_control_byte SP2_to_MCU_buffer 0 RX byte count SP2 to MCU buffer 0 amp Ox3F else if RX byte count gt 0 RX byte count if Getting control byte 0 amp amp RX_byte_count 0 Getting control byte 1 MCUCR MCUCR 0x02 RXA 1 RX state RXR tranreg Lab end break 30 void main void begin initialize while 1 if time0
24. ent packet loss Packet framing and error checking is user transparent Third it has a reliable range of 50m in building and 200m outdoor 3 3 Accelerometer An initial design included an accelerometer of 10g with analog output It was hoped to fit the system into various application with a lager range In addition to this the project is designed to measure all X axis Y axis and Z axis It is difficult to find a tri axis accelerometer with a suitable range since most accelerometers are designed for industrial purpose While most accelerometers are used in industries the cost is not low As a result only a dual axis accelerometer of 2g with analog output is available to be sampled from Analog Devices During implementation two dual axis accelerometers are arranged in a way that all three axes are perpendicular to each other There is one axis of an accelerometer is left disconnected from microcontroller 3 4 Data Processing Data are collected and processed in three stages and each stage can process the information in different ways It is entirely up to the developer on what data he wants to have at each stage 1 Accelerometer s outputs are analog and they are processed by microcontroller s ADC and then transmitted out 11 Data received in base station s hardware are manipulated to convert to percentage After some mathematical manipulation the data before transmitting through serial communication to a computer are in perc
25. entage of 2g ili At the hyper terminal data are arranged into a matrix with three columns After collecting the necessary data a file is saved by capturing the matrix Then a Matlab program is opened and the data is once again processed by the program At this final processing data in percentage are converted into data in unit g and this translation shows the real accelerations that have recorded This scheme of handling collected data in the above way eased the programming effort and it will be elaborated later in this report 4 Design and Implementation The acceleration measuring system includes two major hardware and two major software programs The hardware is the remote end s hardware and the base station s hardware The software programs are the embedded application and Matlab program A block diagram of the system is shown below Remote end digital Huper Terminal Matlab 4 1 Remote end hardware Remote end s hardware is the device that will be carried by a user Lots of efforts have been spent to make it compact light and reliable Overall the device consists of three major parts and they are microcontroller accelerometer and radio packet controller All of the major components are elaborated in the following sections There is a color scheme used in this project and they are Red 9V Yellow 5V Black ground White data signals between MCU and SP2 or X axis Blue transmis
26. fferent period of time One axis was tested along its positive and negative axis while the other two axes were kept still X axis was tested from 8 second to 10 second Z axis was tested from 10 second to 12 second Finally Y axis was tested from 14 second to 16 second Figures of X axis Y axis Z axis combined axes and scalar quantity of combined axes are shown in Appendix F 19 6 Conclusion This project has fulfilled my desire to build a system based on microcontroller I have been able to apply my electrical and computer engineering background to finish the task The project was based on heavy research and planning Any alternative solutions had been considered carefully The system is kept compact throughout the implementation and layout of prototype board was carefully designed During the project I did not encounter any major problems and developing the system went well Overall I enjoyed working on this project I have trained myself to be good at soldering parts even with surface mount capacitors I have learned to be patient when debugging hardware and software Most important is that I know how to make decision when there are alternative solutions pointing into same or different directions There are many additions which could be made to the basic system I built If there were more manpower this project could be expanded greatly and more interesting features could be added into the system Instead of just getting
27. fter being connected Signal lines such as TXR TXA RXR RXA and Reset are Active Low which means they are activated enabled when low is passed into the signal line Datasheets found on various Radiometrix s websites are inconsistent and may mislead developers When implementing the SP2 it gave me one difficulty that is worth to mention here The SP2 is manufactured by Radiometrix Limited which bases on England The size of the module is fairly compact and when I was trying to solder the SP2 into a prototype board problem happened The SP2 would not fit into a standard 0 1 spacing board The spacing of the pins is 2mm in that case a 2mm grid prototype board is needed After so much effort had spent on the web in searching for the right board a relatively expensive board was found from Digikey but there was no luck to find a socket that would fit the SP2 And that is why the expensive SP2s are soldered onto the board directly 10 4 2 Base station hardware Base station is responsible for receiving collected data manipulating received data into percentage format and sending to a computer through a serial communication RS232 for a graphical analysis It consists three major parts which are microcontroller radio packet controller and serial communication hardware Microcontroller The connection of microcontrollers in both the base station s hardware and remote end s hardware are nearly identical The only differ
28. h to acknowledge that data has been read Then the steps are done again for the higher 4 bit Process will repeat until the entire packet is read Notice that data lines should be set as input before initiate a transfer request They will only be set as output during a transmitting operation External interrupt 1 is used as RXR MCU needs to detect a falling or rising edge of RXR and it works by setting register MCUCR 3 2 to 10 or 11 respectively Also GICR 7 must be set to enable the external interrupt 1 requested 16 4 4 Matlab application Matlab is chosen to analysis data in graphical interpretation because of its powerful mathematical and graphical tools Through the serial communication a matrix with three columns is displayed on Hyper Terminal Data received on Hyper Terminal is saved into a text file on a directory The matrix s column is separated with a space and Matlab can easily load the text file into workspace Once data loaded a matrix variable called data_percent is created Then data_percent is processed and converted into a new matrix with unit g The new matrix is saved into variable named data_g The range of data_g should be from 2g to 2g Each column of data_g is saved into a new variable representing its specific axis Five graphs are plotted and first three graphs show X axis Y axis and Z axis data respectively Fourth graph shows all three axes and fifth graph shows the scalar quantity of all three axes
29. han just some abstract fancy programming In addition to this I was able to apply both hardware knowledge and software programming skill into the project Using radio packet controller for the wireless connection in this design gives advantages such as longer reliable range lower cost and most importantly the possibility of extending the project s goal into a small personal network with multiple client systems The accelerometers can be easily replaced with any desired acceleration range and only a little modification is needed to be done on the embedded programs One of the main goals of this project is simplicity The system should be reliable and a friendly easy to understand result should be available to user Hence the final data is in a matrix form so that it will be easy to import into software such as Excel or Matlab A user manual is provided in Appendix G to show how to get a graphical interpretation of collected data in Matlab 2 Design Problem and System Requirements 2 1 Design Problem The goal of this project is to design a low cost compact and reliable acceleration measuring device It should also be expandable into multiple clients system with few code modifications A simple graphical interpretation should be available to analysis the collected data The system is composed with two major hardware and they are remote end s hardware and base station s hardware Remote end s hardware is responsible in collecting analog
30. irst a 10 bit resolution is used for the AD conversion in which means 1023 is the maximum digital count Then the ADC data register is left shifted and the higher 8 bit which is register ADCH is chosen The measured analog signals from the accelerometers are referenced with 5V supply voltage and the equation of getting digital count of the analog signals is X 1023 Accelerometer s signal level 5V A list of the equivalent values of accelerometer s output in different forms is shown below Ing In voltage Higher 8 bit digital count 2 10100000 0xA0 1 10010000 0x90 0 10000000 0x80 1 01110000 0x70 2 01100000 0x60 Since two dual axis accelerometers are used they are arranged in a way that all three axes are perpendicular to each other A strong Wire is used to hold them as close as possible at 90 degree X axis and Y axis of first accelerometer are read as X axis and Y axis of the system X axis of second accelerometer is read as Z axis of the system and Y axis of second accelerometer is left disconnected from microcontroller Example of an accelerometer orientation is shown below Y axis ve ADXL311 0309 X axis ve X axis ve Y axis ve After carefully aligning and connecting them together they are tested individually since each accelerometer may differ from another on electrical characteristics As a result of this testing the theoretical values of accelerometer
31. log com UploadedFiles Data Sheets 39398238692761ADXL311 a pdf National Instrument 5V voltage regulator LM78M05 http www national com ds LM LM341 pdf CodeVision AVR evaluation download http www hpinfotech ro html download htm 49
32. n 1 2 Date 12 06 2003 Author Wong Kim Fung Company Cornell University Comments Program is complete and functions Chip type ATmega32 Program type Application Clock frequency 16 000000 MHz emory model Small Internal SRAM size 2048 External SRAM size 0 Data Stack size i 512 KOKCKCKCKCKCKCk I Ck K K Ck KKK KKK kck ck KKK KKK KKK KKK ke e x kx f LEDs indicator Green transmitter enabled Red receiver enabled Orange preamble detect d Yellow valid packet received include Mega32 h include lt string h gt include lt stdio h gt include lt stdlib h gt define begin define end define ADC_diff 0x20 SP2 reset define SP2 reset PORTD 7 define TXR PORTC 6 TXA define RXA PORTC 5 RXR SP2 states define TXA regaccept lsb define TXA dataread Lab define RXR tranreg Lab define TXA regaccept msb define TXA dataread msb define RXR tranreg msb Global variables define RXR datapresent lsb define RXR datapresent msb difference of 2g amp Og in digital count MCU SP2 transfer signals PIND 2 PIND 3 1 2 3 4 5 6 7 8 Control byte for SP2 receiver unsigned char RX control byte Counter for receiving bytes unsigned char RX byte count Position for receiving bytes unsigned char RX byte pos 23 Buffer for data packet unsigned char SP2_to_MCU_buffer 4 flag for getting Cont
33. nclusion aysa re Ea e e bo d OPER EEE 20 7 Acknowledgements 21 Appendix A Cosas 22 Appendix B Schematics 23 Appendix C Remote end microcontroller s Code eee rn 25 Appendix D Base station microcontroller s Code 33 Appendix E Matlab Code 38 Appendix F Matlab result 40 Appendix G User s Manual 45 Appendix H Pictures cj eu YR E teria ex dane savage cue a CA day xa x dE Rara Yeu d ge 46 Appendix I Bibliography 49 1 Introduction Traditional learning method in classroom environment is not always enjoyable While some children do fine in learning fundamental physics with traditional way there are always others who prefer interactive learning This project explores the possibility of building a compact and reliable acceleration measuring device with cost effective solution Its goal is to provide students a tool to enhance their learning experience in classroom In fulfilling the Master of Engineering project requirement I chose to design a system based on microcontroller This gives me a chance to build a tangible and practical deliverable rather t
34. nd the Matlab code is modified a little to combine four graphs into a figure This is because a more understandable illustration can be done in a combine figure Second test result is shown in Appendix F and five graphs including scalar quantity are shown Test 1 At the first test the accelerometer device was moved in a circular motion along XY plane Sine waves were generated on X axis and Y axis Z axis was supposed to be constant at a value of 1g However this test was done by a human being and the interval between each circular motion varied It is very difficult to finish each circle with same period of time and same speed As a result irregular sine waves were generated on X axis and Y axis and Z axis also had values varying around 1g A figure of the test is shown on next page 18 o D S N acceleration g acceleration g 1 1 o 1 N 1 o o Test 2 ker o Acceleration Xaxis 50 100 150 200 samples 10Hz Acceleration Zaxis Du S 50 100 150 samples 10Hz 200 acceleration g acceleration g Cn e Cn 1 1 s Cn o Acceleration Yaxis 50 100 150 200 samples 10Hz Acceleration measurement 3axes luy ee 50 100 150 200 samples 10Hz At this test all three axes were tested at a di
35. onous and there are couple procedures that should be handled before transmitting First if there is a valid packet in SP2 waiting to be uploaded into MCU data must be uploaded before transmitting Second data lines must not be set to output until step 3 After the SP2 has accepted the transfer request data lines could stay as output until the entire packet is sent out Then steps for transmitting data are as follow 1 MCU is ready to transfer data It asserts TXR from high to low to initiate a transfer request MCU waits for SP2 to pull TXA low which means request is accepted MCU set data lines to output and place the lower 4 bit on the data lines MCU set TXR back to high to tell SP2 that data is present MCU waits for SP2 to set TXA back to high to acknowledge that data has been Ur des ke read Then the steps are done again for the higher 4 bit Process will repeat until the entire packet is read External interrupt 0 is used as TXA MCU needs to detect a falling or rising edge of TXA and it works by setting register MCUCR 1 0 to 10 or 11 respectively Also GICR 6 must be set to enable the external interrupt 0 requested 14 Here the base station s program is explained in detail interrupt TIMO_OVF void timer0_overflow void This has the same purpose of the timer counter 0 interrupt that is explained above void Repack_Sendmsg void This function serves two purposes First packet received by the base sta
36. rol byte bit Getting_control_byte unsigned char TX_state unsigned char RX_state for TXC interrupt unsigned char RS_head unsigned char RS_tail i buffer for reorganized packet to PC nt RS_buffer 6 interrupt variables unsigned char reload unsigned int time0 void initialize void begin testing DDRB OxFF PORTB 0xFF MCU to SP2 interface Bit6 TXR Bit5 RXA DDRC 0xF0 PORTC 0xF0 BitO RXD Bitl TXD Bit2 TXA Bit3 RXR Bit7 SP2 reset DDRD 0xF3 try bit0 as output Timer Counter 0 initialization time0 0 reload 256 250 TCCR0 0x03 clk 64 TCNTO reload Timer Counter0 Overflow Interrupt TIMSK 0x01 USART initialization UCSRA 0x00 UCSRB 0x08 transmitter enable UCSRC 0x86 8bit data UBRRL 0x67 9600 baud rate UBRRH 0x00 SP2 initialization SP2 reset 0 TXR 1 PORTC 6 out RXA 1 PORTC 5 out TX control byte 0x04 TX byte count 0 TX byte pos 0 RX control byte 0 34 Enable RX_byte_count 0 RX_byte_pos 0 Getting_control_byte 1 BX done flag 0 TX_state 1 RX_state 3 RS head 0 RS tail 4 GICR 0xC0 External interrupts 0 1 enabled CUCR 0x0A Falling edge generates interrupt Global enable interrupts fasm sei end Timer 0 overflow interrupt service routine interrupt TIMO OVF void timer0 overflow void begin reload to force lms overflow TCNTO reload
37. sion related signals Green receiving related signals or Y axis Purple Z axis value Orange interconnection signals or reset Microcontroller Atmel AVR Mega32 is chosen for the project because of its availability familiar by the developer and its great features such as built in analog to digital converters external interrupts and USART transmission Port A has eight channels of ADC ADCO is connected with X axis of first accelerometer ADC is connected with Y axis of first accelerometer ADC2 is connected with X axis of second accelerometer that is held upright As a result ADC2 is reading Z axis value of the device Port B is connected with LEDs for testing and debugging purpose These LEDs help to debug the embedded program during development It is almost impossible to have program worked the first time without debugging and that is why it is necessary to have these LEDs They can be used to show the data transmitted or which state the microcontroller is at Port C is used to interface with a radio packet controller SP2 PC6 is an output signal connected with TXR of SP2 PCS is an output signal connected with RXA PC3 PC2 PC1 and PCO are bi directional signals connected with D3 D2 D1 DO of SP2 respectively e Port D is also used to interface with SP2 PD2 is external interrupt zero and it is an input signal connected with TXA from SP2 PD3 is external interrupt one and it is an input signal connec
38. ted with RXR from SP2 PD7 is an output signal connected with Reset of SP2 A table with the list of signals connected with the microcontroller is shown below Pin Port Direction Signal 40 PAO X axis 39 PAI Y axis 38 PA2 Z axis 8 1 Red LEDs 28 PC6 TXR 27 PC5 RXA 25 22 D3 D2 D1 D0 21 PD7 Reset gt gt gt olo 16 PDO Input TXA Beside the Port signals basic connections on microcontroller are worth noticing The microcontroller is running at 16MHz with an external crystal A reset button is available on microcontroller and the MCU s reset is activated on low A 9V alkaline battery is used to power up this remote end s hardware Of course there is a SV voltage regulator connected with the battery The voltage regulator is LM78M05 of TO 220 package from National Instrument A 0 1uF capacitor is connected between Vcc and ground to stabilize the source The prototype board that is used is 0 1 inch spacing and it is the most popular standard for most components Accelerometer Analog Devices ADXL311 2g dual axis accelerometer is selected for this project It is operational from 2 7V to 5 25V Its typical sensitivity is 312mv g at 5V and Og is about 2 5V Notice that the typical sensitivity changes with different input voltage and each accelerometer has different electrical characteristic Accelerometer s output is in analog which is desired since the MCU has the built in ADC F
39. tion is called by passing a value to read the accelerometer s signals The value passed is a channel number such as ADCO ADCI or ADC2 The function allows one ADC reading at a time Although multiple ADC readings are allowed with Mega32 it is safer and more accurate to read one channel at a time This is done by a flag called ADC doneconversion which indicates if an ADC channel is being read void Taskl unsigned char ADC value This function is for debugging purpose It tests whether the accelerometer s signals are correct and it is done by reading a converted value of one of the three channels The value read must be within a range from 0x60 to Ox AO explained in section 4 1 Accelerometer One channel at a time is tested 13 void Task2 unsigned char ADC vl unsigned char ADC_v2 This function is for debugging purpose It is very similar to the Task function above However instead of testing one channel s value at a time two channel s values are compared with the range from 0x60 and OxAO This function is used to prove that microcontroller is reading multiple channels properly e interrupt EXT INTO void ext intO void detect TXA MCU to SP2 transfer The function is processed by an external interrupt 0 and it is used for the microcontroller to acknowledge that SP2 is ready for the data transfer Detail on how it operates is explained below MCU to SP2 Transmission Doing a byte transfer from the MCU to the SP2 is asynchr
40. tion s microcontroller is in digital count Here the packet is converted into percentage of the acceleration and the range is from 100 to 100 This conversion could actually be done by the remote end s microcontroller However in order to minimize the amount of data transmission through the radio packet controllers the conversion is done at the base station to maintain data integrity Second the function calls built in function printf to send data through USART Using printf function saves a lot of time on writing codes for the USART Although the compiler generates a significant amount of assembler codes by handling printf it only generates a few codes after calling it the first time So considering the pros and cons of using printf I chose to implement it to ease the programming effort interrupt EXT_INT1 void ext intl void detect RXR SP2 to MCU transfer The function is processed by an external interrupt 1 and it is used for the microcontroller to know that SP2 is ready for data upload Detail on how it operates is explained below 15 SP2 to MCU Receiving Doing a byte transfer from the SP2 to the MCU is asynchronous and steps are shown below 1 SP2 asserts RXR low to initiate a transfer request 2 MCU pulls RXA low to tell SP2 that request is accepted 3 SP2 places data on the data lines and sets RXR back to high to tell MCU that data is present 4 MCU reads the data from data lines and set RXA back to hig
41. xes xlabel samples 10Hz ylabel acceleration g print djpeg 100 result jpg figure plot vector_guan title Acceleration measurement scalar quantity of 3axes xlabel samples 10Hz ylabel acceleration g print djpeg100 scalarguan jpg 39 Matlab result Appendix F L p E m R Ra a Lane e E ec 7 _ s a E A n 4 2 NN ES B Y Y FN 223 SE i dem LE um 6 uopeiejeooe 40 60 80 100 120 140 160 180 samples 10Hz 20 A movement on X axis was performed along positive and negative direction 40 Acceleration Yaxis 12 I I l 0 8 o o T D o N acceleration g 0 6 i i i i i i i 0 20 40 60 80 100 120 140 160 180 samples 10Hz A movement on Y axis was performed along positive and negative direction 41 Acceleration Zaxis 0 2 T T I T T T T T S o T acceleration g o co T l 20 40 60 80 100 120 140 160 180 samples 10Hz A movement on Z axis was performed along positive and negative direction 42 Acceleration measurement 3axes 180 1 5 T T T T T T T I X axis Y axis Z axis ab a 05r 4 I l m I 2 or 4 6 N prem L ay 8 8 05 DOE 4 1 TN d FK ka J U 1 5 a 2 l l l l l l l 0 20 40 60 80 100 12
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