Rfid F04 Final

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  • 8/8/2019 Rfid F04 Final


    EE495M Mobile

    Communication Project

    RFID Team

    Final Report


    Bader AlDalali [email protected]

    Shan Bai [email protected]

    Vivek Vijay [email protected]

    Ben Chen [email protected]

    Due Date: December 12 th , 2004

    mailto:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]
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    Executive Summary:

    The RFID team has accomplished all the tasks they set at the beginning of the semester.

    The tasks included interfacing a temperature sensor to the tag circuit, adding a switching

    method to send data to the reader, retrieve data on reader and display temperature and I.D

    data periodically.

    The analog temperature sensor has been integrated with the tag circuit. An A/D converter

    has been added to the sensor to output the 8-bit binary data. A PLD has been used to

    convert the binary output into BCD data.

    For the rest of tag circuit, two nine volt batteries have been used as power source to drivethe switch. The shift register circuit is implemented by timer, counter, dip switch inputs,

    and the PISO shift registers.

    For the reader, the final design included a few circuits. The circuit that provided the

    clock had a 555 timer, with an edge detector, a counter, and a PLD that produces the

    required clocking pulse. The second circuit included the shift registers, two PLDs that

    latched the data, and the enable circuit. The third and fourth circuits included the 7-

    segment decoders and displays for the ID and temperature data.

    The main task for future teams would be to work on the RF data receiving range, the

    speed of data transmission, and the of the circuit.

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    Delivery Project Summary:

    The goal of this semesters RFID project is to measure temperature data and transmits it

    with I.D. data to the reader circuit, and displayed by 7-segment LEDs. The technique for

    data transmission is by using amplitude modulation. This is accomplished by using a

    switch circuit. The data are generated from temperature sensor, converted from an analog

    output to parallel digital outputs, and transmitted by using parallel-in, serial-out shift

    register to send the data through the switch circuit.

    On the reader side, the original circuit reads the signal and converts it to digital signal.

    The received BCD data is then shifted into the 7-segment displays and displays the

    specific ID number with the corresponding temperature.


    Ben Chen

    This RFID project has been another great engineering project experience after completion

    of senior design last semester. Through out the project, I have learnt additional

    engineering experience in transistor theory and think of methods to implement

    telecommunication theory into circuits. Most importantly, I have had a great time

    working with my teammates, Bader, Sean, and Vivek. I am very grateful for the

    opportunities to work together with them for the design, integration, knowledge sharing. I

    would also like to thank Professor Krogmeier, Srinivas, and Foo; for providing us

    recommendation and debugging for the design, and an experience closer to real world.

    Sean Bai

    Good project, good team, good effort, good experience.

    Bader AlDalali

    As an ECE senior this was the first project that actually gave me a hands-on experience

    on present research projects. It also enabled me to utilize my background in ECE and all

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    the theories that I studied and thought were useless. This project also gave ma a chance to

    work with such a qualified and hardworking team which includes the students, the T.A.s,

    and the Professor, and the success of our project was based on everybodys hard work.

    Vivek Vijay

    This project has helped me understand the theories I have learnt so far in a practical way.

    It has also given me some hands on experience and a kick start for my Senior Design

    class. It has been a great pleasure to work with a group like this, with enthusiastic people

    like Ben, Bader and Sean who were always there to help me and work on our project. I

    would like to take this opportunity, to thank Professor Krogmeier, Srinivas, and Foo for

    helping us and giving us all the encouragement in turning this project to a great success.


    RFID, as everybody knows is one of the most innovative technologies in the wireless

    sector. It is one of the solutions for many problems today in the wireless area. It replaces

    bar codes, authorizes for access of protected areas, I-pass on toll ways, and provides body

    temperature readings for physically challenged people.

    The RFID team for Fall2004 proposes to build an RFID circuit that will be able to detect

    temperature and transmit the information from the tag to the reader, eventually displaying

    the actual reading on the reader side.

    In order to meet the design requirements, the RFID team has identified the challenges

    that need to be overcome.

    1. How to transmit data from the tag to reader circuit?

    2. How to interface a temperature sensor with the tag circuit?

    3. How to implement the data display on the reader circuit?

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    Project Description:

    I. Data Transmission Theory

    As mentioned in the introduction, the goal in this data transmission project is to transmit

    and display data on the reader circuit. As tag come into range to reader, the LC circuit

    will create resonance. To enable data transmission, the RFID team is using amplitude

    modulation, or AM, by using a switch to create short or open circuit on the tag end.

    Figure 1: Left - AM Signal with switch operating at 1 Hz

    Right Zoom-in of the AM signal, displaying the carrier frequency at 1 MHz

    II. Tag circuit switch

    From measurement, the voltage of tag coil is 17 V pp when it comes in range with reader coil. As described in the progress report, MOSFET devices are considered as the ideal

    switch device for the tag circuit. Since the tag voltage drops down to as low as -8.5 V, the

    CMOS bilateral switch CD4066 is used with two 9 V size D alkaline battery to provide

    over 17 V pp . From measurement, when the input is not -9 V, the output will be open.

    Thus, an inverting amplifier is placed before CD4066. Thus when the input is high, it will

    be inverted and create a short.

    Vin/R5 = - Vo/R4

    Vin/-Vo = R5/R4 = 294/880

    Vin = 5V, Vo = -9V

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    R 4

    8 8 0

    R 5

    2 9 4







    U 1 3 A

    L M 3 9 3

    C D 4 0 6 6 B C

    1 3

    1 4




    Control A




    V D D

    V S S

    t a g c a p



    t a g c o i l

    R 61 k

    V 1

    Figure 2: Inverting amplifier and switch circuit

    III. Shift Register Circuit

    As desired to transmit 8 bits of I.D data and 8 bits of temperature data, the 74LS165

    PISO shift registers are considered as the ideal data shifting method. The PISO consists

    of 8 parallel input, 1 serial input, an active low load input, a clock input, and an output

    QH. The astable operation of LM555 is used to generate clock signal at 1 Hz. Two HC393

    up-counters are used to generate 24 clock cycles to provide clear. However, since 24 is

    not in the power of 2, the output of up-counter is put into NOR gates, AND gates, then

    inverter, to create active low for the load pin of shift registers. The data are loaded and

    transmitted repetitively in every 32 clock cycles.

    The start bits, end bits, and ID bits are connected to the parallel input of shift registers.

    The temperature data is connected from the Binary-to-BCD PLD from the temperature

    circuit. The serial input of the least significant bit (DS from the bottom shift register) is

    connected to ground. So any other input data is considered as zero. The output Q H is

    connected to the serial input of each shift register. The output of the top shift register is

    then outputted to the inverting amplifier.

    Because the load pin happens at the falling edge of clock cycle, the most significant input

    (pin 11) of the top PLD is not used as input.

    Vin Vo

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    D S1 0

    P 01 1

    P 11 2

    P 21 3

    P 31 4

    P 43

    P 54

    P 65

    P 76

    C P 12C P 2

    1 5

    P L1

    Q H9

    Q H7

    U 2

    7 4 L S 1 6 5

    D S1 0

    P 01 1

    P 11 2

    P 21 3

    P 31 4

    P 43

    P 54

    P 65

    P 76

    C P 12

    C P 21 5

    P L1

    Q H9

    Q H7

    U 3

    7 4 L S 1 6 5

    D S1 0

    P 01 1

    P 11 2

    P 21 3

    P 31 4

    P 43

    P 54

    P 65

    P 76

    C P 12

    C P 21 5

    P L1

    Q H9

    Q H7

    U 4

    7 4 L S 1 6 5

    Q A3

    Q B4

    Q C5

    Q D6

    C L K1

    C L R2

    U 5 A

    5 4 H C 3 9 3

    O U T3

    R S T4

    V C C8

    C V5

    T R G2 T H R6

    D S C H G7

    U 9

    L M 5 5 5

    Q A3

    Q B4

    Q C5

    Q D6

    C L K1

    C L R2

    U 1 0 A

    5 4 H C 3 9 3

    R 1

    . 3 6 8 M

    R 2. 4 6 9 M

    C 20 . 0 1 u

    C 11 u

    V 15 V d c

    V C C

    V 1



    U 1 1 A

    7 4 0 2



    U 1 1 B

    7 4 0 2



    U 1 2 A

    7 4 0 8



    U 1 2 B

    7 4 0 8


    1 08

    U 1 2 C

    7 4 0 8

    V 29 V dc

    V D D

    V S S

    V 39 V d c

    T e

    m p e

    r a t u

    r e

    D a t a

    1 2U 1 4 A

    7 4 0 4




    t s

    ( Al l




    S t a

    r t


    t s

    ( Al l







    Figure 3: Shift Register Circuit

    IV. Temperature Sensing Circuit

    A simple and easy-to-integrate type of temperature sensor needs to be selected so the

    measured data can be transmitted wirelessly and output on some 7-segment displays on

    the reader circuit end. Voltage output and digital serial output sensors are the two major

    types being considered for use. Digital sensor is the most ideal; however due to the

    constraint of interfacing with shift registers that normally have parallel inputs, choosing

    an analog sensor will be a more practical approach. For this particular project, the LM35

    or the precision centigrade temperature sensor is adapted and its functionality has been

    tested and proven. After properly connecting the sensor on the breadboard, an output

    voltage linearly proportional to the Celsius temperature can be observed when human

    thumb is firmly pressed against the chip.


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    was connecting to the incoming data, the PLD for some reason did not provide the

    required pulse. Therefore we simply connected the input to the edge detector to ground,

    which is the same as not using the edge detector circuit at all.


    Q3..Q0 pin;SCLOCK PIN istype com;CRESET PIN istype com;Edgedetector pin;


    The shift registers then start shifting whenever it is provided with the clock.

    The data is continuously being shifted by our SIPO shift registers. In order to display the

    correct temperature with its corresponding ID, we made use of 4 1 Start bits and 3 1

    Stop bits, which were fed into a 4-input AND gate. The result of this goes into our 2-

    input AND gate, to give an output high only when all input bits were high. The output of

    our AND gate was the enable of our PLD. The PLD works on the same bases of a PIPO

    shift register, except for the fact that the input and the output pins are different. The Abel

    code for the PLD is below.

    ABEL Code to Replace the PIPO shift registers:

    CLOCK pin 1; LOAD pin 2;I7..I0 pin;D7..D0 pin istype 'reg_d,buffer';EQUATIONS

    [D7..D0].d = LOAD & [I7..I0] # !LOAD & [D7..D0].q;[D7..D0].CLK = CLOCK;

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    Once the enable is high, the PLD latches the data currently present in the SIPO shift

    register. This is then displayed on the common anode 7 segment displays using the LS47

    7 segment decoders.

    Figure 6: Complete Reader circuit

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    1 August 232 August 30

    3 September 6

    4 September 13

    5 September 20

    6 September 27

    7/8/9 October 4

    October 11

    October 18

    10/11 October 25

    November 1

    12 November 8

    13 November 15

    14 November 22

    15 November 29

    16 December 4


    Team formingInitial meeting and set goals

    Analyze past design and theory

    Design reconstruction and testing

    Proposal review and continual research

    Preliminary design

    Tag modulation / Sensor Interfacing / Clock

    synchronization / 7-Segment Display design

    Mid-term Presentation

    Design / Progress report

    Design implementation

    Design implementation

    Design implementation

    Thanksgiving Break

    Testing / Final design review/ Outcome matrix

    Integration / Final presentation

    Semester Outcomes

    The RFID team has successfully designed, built, tested, and implemented the temperature

    sensing data transmission project. The tag circuit has effectively captured the temperature

    data and converted the analog into digital data in BCD format, then transmitted to the

    reader circuit by using shift registers and switch. The reader circuit has created a clock

    and shifted the data into PLDs, and displayed it correctly. The clock synchronization part

    on the reader side did not work as it was designed. The problem we believe is within

    incorporating the edge detector into the rest of the circuit.

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    At the moment, this system is capable of detecting temperature ranges from zero to 40

    degree Celsius while the tag circuit is completely inside the reader circuit. So far, the

    overall system consists of nine breadboards, and the speed of data transmission is

    operated at 30 seconds per cycle. There is leeway to improve the current project by

    means of increasing the rate of transmission and changing the conductor value to better

    RF receiving range. It is also achievable to broaden the temperature range by building a

    more exhaustive truth table, and solder all components on PCB to provide mobility and

    lower power consumption.

    Transition Plans

    The future RFID staff can always refer back to the documents and schematics created bythe previous semesters team for further design details. However since the goals for this

    semester has already been achieved, future staff can utilize these available resources

    based on what their project goals are.

    Conclusion and Recommendation

    This was definitely one of those projects that presented us with different challenges.

    Throughout the semester the different parts of the project started to take their final shape

    and eventually we integrated all the parts and achieved our goals of displaying

    periodically the ID and temperature data.

    One of the problems that we faced and hindered our progress was finding vacant space in

    the labs to work on our project. We recommend arranging a certain lab for future teams

    and have all the materials they need available to them.

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    [1] Bryan A. Chin. (2003). Radio Frequency Identification Sensors [WWW document]

    URL http://www.audfs.eng.auburn.edu/docs/Nambisci2003.pdf

    [2] P. Sorrells, Passive RFID basics, Microchip Technology Inc., 1998.

    [3] MAX6613 Low-Voltage Analog Temperature Sensor. [WWW document]

    URL: http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3420 .

    [4] The RFID Handbook , Klaus Finkezeller, Wiley and Sons, Munich, 2000

    [5] Microchip AN710 Antenna Circuit Design for RFID Applications Datasheet

    [6] Asynchronous and Synchronous communications [WWW document]

    URL: http://www.jbmelectronics.com/products/sync&a.htm

    [7] Art of Electronics, Paul Horowitz, Cambridge England, 1989

    Teaching Assistance

    1. Professor James V. Krogmeier

    2. Professor Robinson

    3. Srinivas Vanjari, Ph D. student

    4. Bingrui Foo, EE495M teaching assistant

    5. Advait Behara, previous semesters RFID team member