Texas Instruments RFM003B Users Manual

November00 Preface
Series 2000 Reader System
Mini-RFM RI-RFM-003B
Reference Guide
11-06-29-030 November 2000
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Mini-RFM - Reference Guide November ’00
Edition Three - November 2000
TIRIS Mini-Radio Frequency Module
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Therefore, TI assumes no liability and is not responsible for customer applications or product or software design or performance relating to systems or applications incor­porating TI produ cts. In addi tion, TI assu mes no liab ility and i s not respons ible for infringement of patents and/or any other intell ectual or industrial proper ty rights of third parties, which may result from assistance provided by TI.
TI products are not designed, intended, authorized or warranted to be suitable for life support applications or a ny othe r li fe cr iti ca l appl ic ati on s wh ic h cou ld inv ol v e po ten­tial risk of death, personal injury or severe property or environmental damage.
RI-RFM-003B
The Incorporated.
Copyright  2000 Texas Instruments Incorporated (TI) This document may be downloaded onto a computer, stored and duplicated as nec-
essary to support the us e of the related TI products. Any othe r type of duplicatio n, circulation or storage on data carriers in any manner not authorized by TI represents a violation of the applicable copyright laws and shall be prosecuted.
logo and the word
TIRIS
TIRIS
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are registered trademarks of Texas Instruments
About This Guide
Conventions
PREFACE
Read This First
This manual describes the TIR IS Mini-Radio F requency Module (M ini-RFM), it pro­vides the information that you will need in order to install the Mini-RFM into your RFID system. It is generally targeted at systems integrators or value added resellers.
Regulatory, safety and warranty notices that must be followed are given in Chapter 6.
WARNING:
A
WARNING IS USED WHERE CARE MUST BE TAKEN, OR A CERTAIN
PROCEDURE
TO
HARM
MUST BE FOLLOWED IN ORDER TO PREVENT INJURY OR
YOUR HEALTH
.
If You Need Assistance
Application Centers are located in Europe, North and S outh Amer ica, the Far E ast and Australia to provide direct su pport. For more information, please contact your nearest TIRIS Sales and Application Center. The contact addresses can be found on our home page:
CAUTION:
This indicates information on conditions which must be met, or a procedure which must be followed, which if not heeded could cause permanent damage to the equipment or software.
Note:
Indicates conditions which must be met, or procedures which must be followed, to ensure proper functioning of the equipment or software.
Information:
Indicates information which makes usage of the equipment or soft­ware easier
http://www.tiris.com
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Mini-RFM - Reference Guide November ’00
Document Overview
Page
Chapter 1: Product Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1 General............................................................................................... 6
1.2 System Overview ............................................................................... 6
1.3 Product Description................................................................. ...... ..... 6
1.4 Mechanical Construction.................................................................... 7
Chapter 2: Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.1 General............................................................................................... 9
2.2 Transmitter ......................................................................................... 9
2.3 Receiver ........................................................................................... 11
2.4 Antenna Circuit................................................................................. 11
Chapter 3: Connectors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.1 Connector Location .......................................................................... 14
3.2 Connector ST1 ................................................................................. 15
3.3 Connector ST2 ................................................................................. 16
Chapter 4: Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.1 Recommended Operating Conditions .............................................. 18
4.2 Electrical Characteristics.................................................................. 18
4.3 Timing Characteristics...................................................................... 20
4.4 Mechanical Data............................................................................... 21
Chapter 5: Installation and Use. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.1 Mechanical Mounting ....................................................................... 23
5.2 Supply Voltage ................................................................................. 23
5.3 Receiver Signal Strength Output RXSS-.......................................... 25
5.4 Programming a Transponder ........................................................... 27
5.5 Antenna Requirements..................................................................... 27
5.6 Antenna Tuning................................................................................ 29
Chapter 6: Warnings, Cautions and Notices . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6.1 FCC / Telecommunications Regulations.......................................... 32
6.2 Important Note to Purchasers/Users of the Mini-RFM in the USA ... 32
6.3 Warning............................................................................................ 32
6.4 Cautions ........................................................................................... 32
List of Figures
Figure 1: The RI-RFM-003B........................................................................... 6
Figure 2: Mini-RFM Block Diagram.............................................................. 10
Figure 3: Mini-RFM’s Antenna Circuit .......................................................... 12
Figure 4: Top View....................................................................................... 14
Figure 5: Bottom View.................................................................................. 14
Figure 6: Maximum Supply Current I_VSP versus t_off (Power Stage)....... 19
Figure 7: Mechanical Dimensions - Top View.............................................. 21
Figure 8: Mechanical Dimensions - Side View............................................. 21
Figure 9: PCB Mounting Proposal................................................................ 23
Figure 10: Supply Line Wiring for Short Supply Lines.................................. 24
Figure 11: Supply Line Wiring for a Separated Power Supply ..................... 25
Figure 12: Synchronization output Control - Digital Adjustment................... 26
Figure 13: Synchronization output Control - Analog Adjustment ................. 26
Figure 14: Write Pulse Timing for TXCT-..................................................... 27
Figure 15: Stick Antenna RI-ANT-P02A....................................................... 28
Page
List of Tables
Table 1: Module Connector - ST1................................................................ 15
Table 2: Antenna Tuning Connector - ST2 .................................................. 16
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Page
Chapter 1: Product Description
This chapter introduces you to the Mini-RFM. It tells you what the module is for, pro­vides an overview o f the comple te system and the product itself. It also provides a mechanical description of the construction of the Mini-RFM.
Topic Page
1.1 General..........................................................................................................6
1.2 System Overview ...................... ...... ...... ....... ...... ....................................... ...6
1.3 Product Description.....................................................................................6
1.4 Mechanical Construction ............................................................................7
CHAPTER 1
Introduction
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Mini-RFM - Reference Guide November ’00
1.1 General
This manual provides information about the TIRIS Mini-Radio Frequency Module RI­RFM-003B. It describes the module and how to integrate it into your RFID system.
This guide should be used in conjunction with the RFM Sequence Control Reference Manual (document number 11-06-21-049) which describes the timing and sequence of radio communica tions between the TIRIS transponder and the radio frequency module.
1.2 Syste m Overview
The three major parts of a TIRIS system are the transponder, antenna and reader. When a transponder is to be read, the reader sends o ut a 134.2 kHz power pulse
lasting approximately 50 ms to the antenna. The field generated by this power pulse is “collected” by the antenna in the transponder that is tuned to the same frequency. This received energy is stored in a small capacitor within the transponder. When the power pulse has finished, the transponder immediately transmits its data back to the reader, using the energy stored within its capacitor as the power source.
1.3 Product Description
The Mini-Radio F requency Module is an integ ral part of a TIRIS system, toge ther with a control module or unit and an antenna it is use d for wireless i dentification of TIRIS transponders.
Main tasks of the RF module are to send an energizing signal via the antenna to ini­tialize a TIRIS trans ponder, to demodulate the receiv ed transponder identification signal and to write to a tran sponder. The RF mo dule delivers a digi tal data stream and a clock signal for further processing to its control unit or module. Furthermore a field strength dependent digital output is available for synchronization purposes.
Figure 1: The RI-RFM-003B
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November ’00 Chapter 1. Introduction
Its small size and low supply voltag e makes the Mini-R FM well suited for portable Reading/Writing Units, as well as for stationary equipment where medium read/write range and speed is sufficient.
The data input and output lines are compatible with the HCMOS- logic family.
1.4 Mechanical Construction
The RF module has a simple mechanical construction where all the components are mounted on the Printed Circuit Board (PCB). The components of the upper and lower side of the PCB are protected by metal shields. The PCB also carries the connectors ST1, ST2 and the antenna terminals A1 to A3 which are captive nuts soldered to the PCB. These captive n uts allow durable low resistance connection wi th the ring ter­minals of the antenna.
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Chapter 2: Functional Description
This chapter provides an electrical description to block diagram level of how the Mini­RFM works.
Topic Page
2.1 General..........................................................................................................9
2.2 Transmitter ...................................................................................................9
2.3 Receiver ......................................................................................................11
2.4 Antenna Circuit ..........................................................................................11
CHAPTER 2
Electrical Description
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November ’00 Chapter 2. Electrical D escription
2.1 General
The RF module is the interface between the TIRIS transponder and the data pro­cessing unit of a TIRIS Reader. It contains circuitry to:
- send a charge-up signal to a TIRIS transponder
- program a read/write transponder
- to receive the signal from the transponde r and to prepar e the recei ved signa l for digital decoding.
Figure 2 shows the block diagram of the RF module and unless otherwise noted the following description refers to this schematic.
2.2 Transmitter
The transmitter control logic generates the transmitter output frequency from a crystal-controlled oscillator. This signal is amplified by the push-pull transmitter power stage which is connected to the antenna terminal A1. The supply current I_VSP of the tran smitter ou tput stage d epends on t he quality factor of the antenna being used and the supply voltage VSP. The Mini-RFM’s antenna circuit is shown in Figure 3.
CAUTION:
Because of the necessarily low impedance of the output stage, a short-circuit from antenna terminal A1 either to the ground or to the supply voltage can damage the output stage if the supply current is not limited.
The transmitter cont rol signal TXCT- activates the transmi tter as long as it is “low”. In receive mode when TXCT- is “high” the antenna terminal A1 has a low impedance path to the ground.
The transmitter power control signal TPC controls the intensity of the transmitter charge pulse by changing the duty cycle of the power stage control signal. The level of the RF power output can be reduced by setting the TPC signal to “low”. TPC con­trols the power setting of the RF sign al which is use d to make- up the “ powe r-bu rst” . Both input signals TXCT- and TPC have internal pull-up resistors.
Because of the limited heatsink possibilit ies of the transmi tter power transis tors the duty cycle of the power pulse must not be allowed to exceed that shown in Figure 6.
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Mini-RFM - Reference Guide November ’00
Figure 2: Mini-RFM Block Diagram
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November ’00 Chapter 2. Electrical D escription
2.3 Receiver
The receiver comprises three parts: the RF part, the interface and the logic. The selective amplifier in the RF Part of the receiver:
- amplifies the RF signal received from the antenna circuit, then
- demodulates the FSK signal from the TIRIS transponder, and
- generates an analog voltage (RSSI) that provides an indication of the received
signal strength.
The demodulated FSK s ignal, carrie r signal and analo g signal stre ngth voltage ar e all connected to the rece iv er inte r fac e. The de mod ulated data signal and the car rier signal are conver ted to logi c si gnals , and conne cte d to th e re ceiv er logi c for fur ther processing. The sig nal strength ind icator voltage is converted i nto RXSS- which is fed directly to the mod ule connector ST1. The function of the RXSS- sig nal is ex­plained in more detail in section 5.3.
The receiver logic gen erates the receiver dat a signal RXDT and the receiv er clock signal RXCK to allow a simple data processing. The NRZ data stream of RXDT con­tains the identification data, the protection data and the framing bits. The clock signal RXCK is used as time reference for the data stream of RXDT. The RXCK signal changes from “low” to “high” level in the middle of each data bit.
2.4 Antenna Circuit
Figure 3 shows a simplified schematic of the antenna circuit. The antenna coil L_ANT is not part of the module b ut together with the anten na circuit’s built-in c apacitors it forms a resonanc e cir cuit. The resonant cu rren t through the antenna co il gen erates the magnetic field which charges (and programs) the transponder.
For the system to transmit and receive correctly, the antenna must be precisely tuned to the transmitter output frequency f_TXO to compensate for the (allowed) tolerances of the antenna coil L_Ant and the antenna capacitors C_A1 and C_A2. To enable this tuning, six tuning c apaci tors C_A T1 to C_AT 6 have b een added to the ante nna ci r­cuit. Their values a re binary weighted in no rmalized steps of 1, 2 , 4, 8 16 and 32. C_AT1 has the smallest value corresponding to the normalized value 1. C_AT2 has the double capacitance of C_AT1, so that C_AT2 corresponds to the normalized val­ue 2 and so on. With this capacitance array and six jumpers, 64 different capacitance values can be tuned. Each of the five tuning pins has its adjacent antenna ground pin for a simple short circuit with jumpers.
The antenna terminal A3 , which is not used in normal applicat ion s and the antenn a ground pins of ST2 h ave same poten tial as GNDP but s hould be use d only for an­tenna purposes and not as a convenient ground connection.
The damping circ uit is pa rt of th e antenna circuit and dam ps the ante nna circ uit by reducing the qual ity factor o f the built- in antenna circuit capa citor con nected to th e terminal A2. The qua li ty fac tor is redu ce d during the receive mod e whe n th e T XCT­signal is “high”.
Information about the tuning of the antenna circuit is given in section 5.6.
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