Texas Instruments RFM003B Users Manual
November ’00 Preface
Series 2000 Reader System
Mini-RFM RI-RFM-003B
Reference Guide
11-06-29-030 November 2000
1
Mini-RFM - Reference Guide November ’00
Edition Three - November 2000
This is the third edition of this manual, it describes the following equipment:
TIRIS Mini-Radio Frequency Module
Texas Instruments (TI) reserves the right to make changes to its products or services
or to discontinue any p roduc t o r se rvi ce at a ny ti me with out not ic e. T I prov id es cu stomer assistance i n various technic al areas, but do es not have full ac cess to data
concerning the use and applications of customer's products.
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
2
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
3
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
4
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
5
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
6
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.
7
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
8
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.
9
Mini-RFM - Reference Guide November ’00
Figure 2: Mini-RFM Block Diagram
10
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.
11
Loading...