RFID Reader Module (#28140)
Contents
1. groan print name remove latch beep restore latch point to first character read character from name if 0 we re done otherwise print it point to next character Parallax Inc RFID Reader Module 28140 Updated 09 2005 v1 1 Page 102. the module will enter its active state and enable the antenna to interrogate for tags The current consumption of the module will increase dramatically when the module is active A visual indication of the state of the RFID Reader Module is given with the on board LED When the module is successfully powered up and is in an idle state the LED will be GREEN When the module is in an active state and the antenna is transmitting the LED will be RED The face of the RFID tag should be held parallel to the front or back face of the antenna where the majority of RF energy is focused If the tag is held sideways perpendicular to the antenna you ll either get no reading or a poor reading Only one transponder tag should be held up to the antenna at any time The use of multiple tags at one time will cause tag collisions and confuse the reader The two tags available in the Parallax store have a read distance of approximately 3 inches Actual distance may vary slightly depending on the size of the transponder tag and environmental conditions of the application When a valid RFID transponder tag is placed within range of the activated reader the unique ID will be transmitted as a 12 byte ASCII string via the TTL level SOUT Serial Output pin in the following format MSB LSB Start Byte Unique ID Unique ID Unique ID Unique ID Unique ID Unique ID Unique ID Unique ID Unique ID Unique ID Stop Byte Ox0A Digit 1 Digit 2 Digit 3 Dig
3. 7 599 Menlo Drive Suite 100 General info parallax com HAA Z Rocklin California 95765 USA Technical support parallax com aN mM Office 916 624 8333 Web Site www parallax com Fax 916 624 8003 Educational www stampsinclass com RFID Reader Module 28140 RFID 54 mm x 85 mm Rectangle Tag 28141 RFID 50 mm Round Tag 28142 lt ____ 2 45 62 2mm jk _ 2 15 54 5mm gt 2 95 75mm 3 25 82 5mm O srano Geena 0 14 3 6mm Introduction Designed in cooperation with Grand Idea Studio http www grandideastudio com the Parallax Radio Frequency Identification RFID Reader Module is the first low cost solution to read passive RFID transponder tags up to 1 34 3 inches away depending on the tag see list below The RFID Reader Module can be used in a wide variety of hobbyist and commercial applications including access control automatic identification robotics navigation inventory tracking payment systems and car immobilization Fully integrated low cost method of reading passive RFID transponder tags 1 wire 2400 baud Serial TTL interface to PC BASIC Stamp and other processors Requires single 5VDC supply Bi color LED for visual indication of activity 0 100 pin spacing for easy prototyping and integration Parallax Inc RFID Reader Module 28140 Updated 09 2005 v1 1 Page 1 The Parallax RFID Reader Module works exclusively with the EM Microelec
4. reliability Parallax Inc RFID Reader Module 28140 Updated 09 2005 v1 1 Page 3 DC Characteristics At Vcc 5 0V and T 252C unless otherwise noted Test Specification Unit Parameter Symbol Conditions Min Typ Max Supply Voltage Voc 4 5 5 0 5 5 V Supply Current Idle lipte 10 mA Supply Current Active loc 90 mA Input LOW voltage Vit 4 5V lt Voc lt 5 5V 0 8 V Input HIGH voltage Vin 4 5V lt Voc lt 5 5V 2 0 V Output LOW voltage VoL Voc 4 5V 0 6 V Output HIGH voltage VoH Voc 4 5V Voc 0 7 V RFID Tags Available From Parallax Parallax provides two passive RFID tags from our on line store We re stocking the tags because many suppliers have high minimums yet many of our customers may only want a few tags for their basic experimentation e 54mm x 85 mm Rectangle Tag 28141 e 50mm Round Tag 28142 2 12 54mm 1 97 50mm E A 17 4 3mm hole E to te 2 oy n 0 8 2 1mm thick v 0 03 0 8mm thick Actual tag dimensions may vary Contact Parallax for specific information Parallax Inc RFID Reader Module 28140 Updated 09 2005 v1 1 Page 4 Optional Tag Information Even though Parallax only carries a Round Tag and a Rectangle Tag the following values were obtained from different tags available in the market ISO Card 6 3
5. Char pntr tagNum 10 4 READ pntr IF char lt gt tag4 THEN Bad Char pntr tagNum 10 5 READ pntr IF char lt gt tag5 THEN Bad Char patr tagNum 10 6 READ pntr IF char lt gt tag6 THEN Bad Char pnts tagNum 10 7 READ pnts IF char lt gt tag7 THEN Bad Char pntr tagNum 10 8 READ pntr IF char lt gt tag8 THEN Bad Char patr tagNum 10 9 READ pnt IF char lt gt tag9 THEN Bad Char GOTO Tag Found Bad_ Char NEXT Bad_Tag SOUND Spkr 25 80 PAUSE 1000 GOTO Main Tag_Found DEBUG tagNum CR HIGH Latch SOUND Spkr 114 165 LOW Latch nar nar nar nar nar nar nar nar nar nar turn of RFID reader lock the door activate the reader wait for header get tag bytes deactivate reader scan through known tags read char from DB compare with tag data all match good tag groan for testing remove latch beep restore latch Parallax Inc RFID Reader Module 28140 Updated 09 2005 v1 1 Page 7 GOTO Main END Beli ea eee RFID BS2 Purpose RFID Tag Reader Simple Security System INUNEINONE 5 a a oo c Parallax Inc All Rights Reserved Feman ITEE support parallax com Started hii Updated 07 FEB 2005 STAMP BS2 PBASIC 2 5 Reads tags from a Parallax RFID reader and compares to known tags stored in EEPROM table If tag is found the program will disable a lock Enable PIN 0 low re
6. W Latch Parallax Inc RFID Reader Module 28140 Updated 09 2005 v1 1 time adjust freq adjust A eS ea AT I Se O04 26S D 28 07665 oo ee G does module have SPRAM RFID bytes buffer character to test from EEPROM table tag byte index character from table valid tags turn of RFID reader lock ethes door Page 9 Main LOW Enable IF No SPRAM THEN SERIN RX T2400 WAIT SOA STR buf 10 ELSE SERIN RX T2400 WAIT SOA SPSTR 10 ENDIF HIGH Enable Claexelie_ialisic g FOR tagNum 1 TO LastTag FOR idx 0 TO 9 READ tagNum 1 10 idx char IF No SPRAM THEN IF char lt gt buf idx THEN Bad Char ELSE GET idx chkChar IF char lt gt chkChar THEN Bad Char ENDIF NEXT GOTO Tag Found Bad_ Char NEXT Bad_ Tag tagNum 0 GOSUB Show Name FREQOUT Spkr 1000 TmAdj 115 FrAdj PAUSE 1000 GOTO Main Tag_Found GOSUB Show _ Name HIGH Latch FREQOUT Spkr 2000 TmAdj 880 FrAdj LOW Latch GOTO Main END Prints name associated with RFID tag Show_Name DEBUG DEC tagNum LOOKUP tagNum Name0 Namel Name2 Name3 idx DO READ idx char IF char 0 THEN EXIT DEBUG char ibe ache 4 i LOOP RETURN activate the reader wait for hdr ID deactivate reader scan through known tags scan bytes in tag get tag data from table compare tag to table read char from SPRAM compare to table all bytes match try next tag print message
7. ader on RX PIN 1 serial from reader Spkr PIN 2 speaker output Latch PIN 3 lock latch control Weep Coimstceumes oso sooo ob esas hae SSeS ie aS SSS SSS Sasa SELECT SSTAMP CASE BS2 BS2E BS2PE T1200 CON 813 T2400 CON 396 T4800 CON 188 T9600 CON 84 T19K2 CON 32 TMidi CON 12 T38K4 CON 6 CASE BS2SX BS2P T1200 CON 2063 T2400 CON 1021 T4800 CON 500 T9600 CON 240 T19K2 CON 110 TMidi CON 60 T38K4 CON 45 CASE BS2PX T1200 CON Ses T2400 CON 1646 T4800 CON 813 T9600 CON 396 T19K2 CON 188 TMidi CON 108 T38K4 CON 84 ENDSELECT Parallax Inc RFID Reader Module 28140 Updated 09 2005 v1 1 Page 8 SevenBit CON 2000 Inverted CON 4000 Open CON 8000 Baud CON T2400 SELECT SSTAMP CASE BS2 BS2E TmAd CON 100 FrAdj CON 100 CASE BS2SX TmAdj CON 280 FrAdj CON 066 CASE BS2P TmAdj CON 3C5 FrAdj CON 044 CASE BS2PE TmAdj CON 100 FrAdj CON SOAA CASE BS2Px TmAdj CON 607 FrAdj CON 2A ENDSELECT LastTag CON 3 DEFINE No SPRAM SSTAMP lt BS2P IF No SPRAM THEN buf VAR Byte 10 ELSE chkChar VAR Byte ENDIF tagNum VAR Nib idx VAR Byte char VAR Byte o EEPROM Data Tagl DATA QFO184F20B Tag2 DATA QFO1D9D263 Tag3 DATA 04129C1B43 Name0O DATA Unauthorized CR 0 Name1 DATA George Johnston CR Name2 DATA Lia Kean Mal lke ral CRO Name3 DATA Mary Evans CR 0 1 Initialization Reset HIGH Enable LO
8. are tags that do not contain their own power source or transmitter When radio waves from the reader reach the chip s antenna the energy is converted by the antenna into electricity that can power up the microchip in the tag known as parasitic power The tag is then able to send back any information stored on the tag by reflecting the electromagnetic waves as described above Active tags have their own power source and transmitter The power source usually a battery is used to run the microchip s circuitry and to broadcast a signal to a reader Due to the fact that passive tags do not have their own transmitter and must reflect their signal to the reader the reading distance is much shorter than with active tags However active tags are typically larger more expensive and require occasional service The RFID Reader Module is designed specifically for low frequency 170 kHz passive tags Frequency refers to the size of the radio waves used to communicate between the RFID system components J ust as you tune your radio to different frequencies in order to hear different radio stations RFID tags and readers have to be tuned to the same frequency in order to communicate effectively RFID systems typically use one of the following frequency ranges low frequency or LF around 170 kHz high frequency or HF around 13 56 MHz ultra high frequency or UHF around 868 and 928 MHz or microwave around 2 45 and 5 8 GHz It is generally safe to as
9. atch 3 lock latch control asss Econs tamto ai E spose soeeasoh eos ees babar ae Sr eSe Sere See Stas SSE aes eaaas SYMBOL lLastTag 2 1 3 caer ico 2 Variables SYMBOL tago BO REID bytes buffer SYMBOL tagi FBT SYMBOL tag2 ZRB SYMBOL tag3 B SYMBOL tag4 BA SYMBOL tag5 B5 SYMBOL tag6 B6 SYMBOL tag7 Jeh7 SYMBOL tag8 B8 SYMBOL tag9 BI SYMBOL tagNum ZTB from EEPROM table SYMBOL pntr BLI pointer to char in table SYMBOL char LZ ehara cterkrEonitaplle Parallax Inc RFID Reader Module 28140 Updated 09 2005 v1 1 Page 6 oases MIPROM Datea j s22ss5ese252s5s5ssssssssseesessnesesesssese Tags EEPROM 0F0184F20B EEPROM 0F01D9D263 EEPROM 04129C1B43 EEPROM 0000000000 EEPROM 0000000000 valid tags space for other tags Initialization Reset HIGH Enable LOW Latch Main LOW Enable SERIN RX T2400 SOA SERIN RX T2400 tag0 tagl tag2 tag3 tag4 SERIN RX T2400 tag5 tag6 tag7 tag8 tag9 HIGH Enable Check List FOR tagNum 0 TO LastTag patr tagNum 10 0 READ pntr IF char lt gt CaO THEN Bad Char pntr tagNum 10 1 READ pntr IF char lt gt tagl THEN Bad Char pntr tagNum 10 2 READ pntr IF char lt gt tag2 THEN Bad Char patr tagNum 10 3 READ pnts IF char lt gt tag3 THEN Bad
10. cm 2 5 10 World Tag 50mm 6 8cm 2 7 10 World Tag 30mm 5 3cm 2 1 10 Bobsleigh Keyfob 5 3cm 2 1 10 Tear shape 4 0cm 1 6 10 Wristband 4 0cm 1 6 10 RFID Technology Overview Material in this section is based on information provided by the RFID J ournal www rfidjournal com Radio Frequency Identification RFID is a generic term for non contacting technologies that use radio waves to automatically identify people or objects There are several methods of identification but the most common is to store a unique serial number that identifies a person or object on a microchip that is attached to an antenna The combined antenna and microchip are called an RFID transponder or RFID tag and work in combination with an RFID reader Sometimes called an RFID interrogator An RFID system consists of a reader and one or more tags The reader s antenna is used to transmit radio frequency RF energy Depending on the tag type the energy is harvested by the tag s antenna and used to power up the internal circuitry of the tag The tag will then modulate the electromagnetic waves generated by the reader in order to transmit its data back to the reader The reader receives the modulated waves and converts them into digital data In the case of the Parallax RFID Reader Module correctly received digital data is sent serially through the SOUT pin There are two major types of tag technologies Passive tags
11. it 4 Digit 5 Digit 6 Digit 7 Digit 8 Digit 9 Digit 10 0x0D The start byte and stop byte are used to easily identify that a correct string has been received from the reader they correspond to a line feed and carriage return characters respectively The middle ten bytes are the actual tag s unique ID All communication is 8 data bits no parity 1 stop bit non inverted least significant bit first 8N1 The baud rate is configured for 2400bps a standard communications speed supported by most any microprocessor or PC and cannot be changed The Parallax RFID Reader Module initiates all communication The Parallax RFID Reader Module can connect directly to any TTL compatible UART or to an RS232 compatible interface by using an external level shifter Absolute Maximum Ratings and Electrical Characteristics Condition Value Operating Temperature 40 C to 85 C Storage Temperature 55 C to 125 C Supply Voltage Vcc 4 5V to 5 5V Ground Voltage Vss OV Voltage on any pin with respect to Vss 0 3V to 7 0V Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device This is a stress rating only and functional operation of the device at those or any other conditions above those indicated in the operation listings of this specification is not implied Exposure to maximum rating conditions for extended periods may affect device
12. sume that a higher frequency equates to a faster data transfer rate and longer read ranges but also more sensitivity to environmental factors such as liquid and metal that can interfere with radio waves There really is no such thing as a typical RFID tag The read range of a tag ultimately depends on many factors the frequency of RFID system operation the power of the reader and interference from other RF devices Balancing a number of engineering trade offs antenna size v reading distance v power v Parallax Inc RFID Reader Module 28140 Updated 09 2005 v1 1 Page 5 manufacturing cost the Parallax RFID Reader Module s antenna was designed with a specific inductance and Q factor for 170kHz RFID operation at a tag read distance of up to 1 3 4 3 inches Example Code The following code examples read tags from a RFID Reader Module and compare the values to known tags stored in an EEPROM table p Paree cary tie RFID BS1 Purpose RFID Tag Reader Simple Security System y ACHO 55 5 5 3 c Parallax Inc All Rights Reserved Weill 6 6 5 support parallax com p Started s Updated 07 FEB 2005 STAMP BS1 i PBASIC 1 0 Reads tags from a Parallax RFID reader and compares to known tags stored in EEPROM table If tag is found the program will disable a lock SYMBOL Enable 0 low reader on SYMBOL RX 1 serial from reader SYMBOL Spkr 2 speaker output SYMBOL L
13. tronics Marin SA EM4100 family of passive read only transponder tags A variety of different tag types and styles exist with the most popular made available from Parallax Each transponder tag contains a unique identifier one of 2 or 1 099 511 627 776 possible combinations that is read by the RFID Reader Module and transmitted to the host via a simple serial interface Electronic Connections The Parallax RFID Reader Module can be integrated into any design using only four connections VCC ENABLE SOUT GND Use the following circuit for connecting the Parallax RFID Reader Module to the BASIC Stamp microcontroller Pin Pin Name Type Function 1 VCC P System power 5V DC input 2 ENABLE Module enable pin Active LOW digital input Bring this pin LOW to enable the RFID reader and activate the antenna 3 SOUT O Serial Out TTL level interface 2400bps 8 data bits no parity 1 stop bit 4 GND G System ground Connect to power supply s ground GND terminal Note Type Input O Output P Power G Ground Parallax Inc RFID Reader Module 28140 Updated 09 2005 v1 1 Page 2 Communication Protocol Implementation and usage of the RFID Reader Module is straightforward BASIC Stamp 1 2 and SX28AC DP code examples SX B are included at the end of this documentation The RFID Reader Module is controlled with a single TTL level active low ENABLE pin When the ENABLE pin is pulled LOW
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