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DEMO90121DA - Digi-Key
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1. Melexis Microelectronic Integrated Systems Features and Benefits Battery operated stand alone RFID reader 10 BOM cost target Low power consumption 400uA average Optimized form factor for easy integration U U U U Ordering Information Part No Description DEMO90121DA RFID Door Access Demonstrator 1 Scope The DEMO90121DA is a turnkey contactless door access example based on the RFID transceiver IC MLX90121 Once set up it detects and reads I5O14443A cards and is capable through software configuration of lighting a red or a green LED As a stand alone application running on battery the current consumption is optimized taking into account a fast response time The form factor is minimized to demonstrate the high level of integration allowed by the MLX90121 The bill of material of DEMO90121DA targets a cost of 10 per component set for 1000 modules Complete schematics bill of material and layout are annexed to this document allowing a fast start for development Source code of the firmware is based on the FW90121 library and is available on the CD ROM provided with the DEMO90121DA This device is based on 15014443A RFID standard but the software library makes it is easy to adapt the firmware to use another ISO protocol DEMO90121DA RFID Door Access Demo User Manual Applications LI Short range contacless Door Access Control Q Short range RFID terminal This document includes fast start instructions de
2. master one 390129012103 Page 11 of 20 User Manual Rev 002 Apr 2008 DEMO90121DA N e lexi 5 RFID Door Access Demo User Manual Microelectronic Integrated Systems Once done the firmware enters in its main loop The RSSI level is measured and compared to the reference stored in the microcontroller memory in order to detect the presence of a tag in the field Without any tag the system will enter into sleep mode for the period defined by the RC circuit connected on PDS If a tag is in the field it starts an inventory according to 15014443A protocol see Figure 10 and reads all the IDs identification codes answering to its requests See Figure 9 Read tag IDs Start Inventory et ID EZ inthe Ho tag ret pore Yes Store tag ID o more tags in the field L Increment index of Put S042 in tag IDs parue r d ann Finished reading tag IDs Figure 10 Reading the tag codes in the field If only one valid tag is in the field the microcontroller sends the command to open the door If there are several valid tags in the field but not the master tag they will be ignored and the door will not be opened See Figure 9 If the master tag is detected together with other tags 15014443A the firmware registers all codes as valid and will reset all previous valid ones In order to prevent valid codes redefinition by error this regis
3. specific needs of the targeted application The long sleep period of about 300ms is hardware based see Figure 12 a RC circuit connected to pin INT1 pin 1 of ATMega8g is discharged from VDD towards the input level LOW triggering in this way an interrupt see Figure 12 390129012103 Page 13 of 20 User Manual Rev 002 Apr 2008 DEMO90121DA N e lexi 5 RFID Door Access Demo User Manual Microelectronic Integrated Systems In order to reduce the power consumption of the device we use POWER DOWN mode of the microcontroller All clocks are stopped and only the watch dog is running The watch dog is reset at the end of the main loop and also after long delays Charge external capacitor from pin o Wdd Frepare Set pin 1 in high imped ance Put UC in pouer don mode 6 Pull up pin 1 Finis hed 200 me sleep Figure 12 Sleep 300ms sequence 390129012103 Page 14 of 20 User Manual Rev 002 Apr 2008 DEMO90121DA N e lexi 5 RFID Door Access Demo User Manual Microelectronic Integrated Systems 10 2 Practical information The firmware of the DEMO90121DA is based on the FW121 library FW90121 Firmware description This library provides the ISO015693 and 15014443 protocol functions as specific commands to control the MLX90121 address its internal registers and read write to the EEPROM of the ATMEL microcontroller At power on or reset
4. 4 L3 C10 CV1 impedance adaptor In order to get the best performance it is necessary to tune the adaptation circuit The tuning operation starts by adjusting CV2 to get the maximum amplitude Once CV2 is fixed the adjustment of CV1 can be done Any 13 56MHz antenna matched to 500 can be used However care should be taken for its quality factor which has to be between 10 and 25 In case antennas with other than 500 impedance the capacitor C9 is used to match the output Tuning of the antenna has to be done when placed in it s final position because close proximity to metallic parts including wires can cause changes from its characteristics in nee air For some tips in building the antenna see 13 56MHz RFID systems and antennas design uide BLM31AJ601SN1 BV C6 G i L2 47pF 100nF 4 7uF Tantal 1 2uH GND_TX R1 1352 2 8 12 5pF i 5V O ON L5 gt 680nH 6 8uH 0 a SO 15pF 3 21 CV j 3 1 ee 5 5 50pF certs R2 as Antenna 1 32 3 18 RSS GND_RX S 10E 4 17 GND TX GND_TX ae 5 16 DSYN C11 100nF TP1 220pF 7 14 MODE Gnd R3 GND_RX Close to 100k 1 DIN Antenna 2 IND uC connector SNC TX O 5V B RIB 10 11 DOUT C13 GND 1X mr Close to pin 7 of A 3ND_uC a TAG Reader MLX9012 EHET Figure 5 MLX90121 transceiver block 390129012103 Page 7 of 20 User Manual Rev 002 Apr 2008 DEMO90121DA N e lexi 5 RFID Door Access Demo User Manual Microelectronic Integrated Systems Reception The reception is done through th
5. L models with different characteristics and prices 9 4 Power The DEMO90121DA embeds a 5V regulator and therefore requires at minimum a 6V DC voltage supply A diode is used after the power connector to protect the board against reverse voltage 5V0 e 10uF Tantal Soldered on a free PCB area of at least lcm2 filled with vias Figure 7 Voltage regulator 5V The MLX90121 has three sets of supply pins power and ground corresponding to its three main blocks the digital block the trans mitter block and the receiver block It is important to separate carefully the supply lines to reduce the noise issues Therefore supply pins are connected as follows the digital block supply pins VSS2 and VDD2 respectively to the microcontroller digital ground and directly to the main 5V the transmiter supply pins to the TX ground plane VSS1 and the VDD1 insulated from the main 5V by a filtering circuit L1 C7 and C1 the receiver supply pins to the RX ground plane VSS3 and VDD3 to the main 5V through another filter L5 C11 The reference clock block of the MLX90121 is internally connected to the transmiter block so the components at pins XIN XOUT should be placed on the same ground plane GND_TX The microcontroller has two different sets of supply pins the digital supply GND_uC and the main 5V and the analog one for the ADC GDN_ADC and AVCC pin supplied from the main 5V through a filter L6 C18 The microcontrol
6. OIDIW jenug 48SN ouq ssae99y 400g AIHH E lt D D a YU L LOpOU 20 DEMO90121DA N e lexi 5 RFID Door Access Demo User Manual Microelectronic Integrated Systems List of components o ae OI JR CI ISA o f oapachor CA y O apar Aaa 150pF 130pF capacitor RIF y S apar O ACA Capacitar O to Cet Capac O to fb OBASI lowpowerdiode Ao D8 ED GI BMM LED to AED RRGBMM LED ao fat Downloader comector to ee TP 9012 tdig Comector 3 Lts BLM AN601SN1 EMIfilter A BUH inductor O RA Yeso 2 RBA OOK resistor R4 R5 R7 RE RA OR O resisto 1 h TT fo i C NO ATmega8 16AU Atmel 13 56MHZ Optional component H Value to be adjusted if necessary 390129012103 Page 18 of 20 User Manual Rev 002 Apr 2008 Mel a DEMO90121DA e exi 5 RFID Door Access Demo User Manual Microelectronic Integrated Systems Layout BOTTOM 390129012103 Page 19 of 20 User Manual Rev 002 Apr 2008 DEMO90121DA N e lexi 5 RFID Door Access Demo User Manual Microelectronic Integrated Systems 14 Disclaimer Devices sold by Melexis are covered by the warranty and patent indemnification provisions appearing in its Term of Sale Melexis makes no warranty express statutory implied or by description regarding the information set forth herein or regarding the freedom of the described devices from patent infringement Melexis reserves the right to change specifications and prices at any tim
7. Page 4 of 20 User Manual Rev 002 Apr 2008 DEMO90121DA N e lexi 5 RFID Door Access Demo User Manual Microelectronic Integrated Systems 5 Connections The first step is to connect the component Connect antenna board to the RFID reader board 3 pin connector Then connect battery cable to the RFID reader board 2 pin connector Plug the battery to the battery connector of the cable 6 Working principle Once connected this demonstrator allows the use of several functions which are generally used in RFID door access devices lts principle is based on the unique identification number UID of IS014443A tags The demonstrator is able to store several UID All cards which UID number is stored in the device can open the door Each card is associated with a specific access privilege Master Key or Valid Key The highest card level Master Key which is unique lt can be only one card with Mater key privilege can transfer its rights to open the door to a card which acquire by this way the second access level Valid Key The device can be re initialized By this way one can change the card with the Master Key privilege and remove all other card from the Valid Key card list When powering on the module or resetting it through its reset button the module starts an initialisation phase e f no tag is present in the reading range of the antenna nothing changes in the configuration The UlDs previously stored in the memory are kept e f one
8. Zz D x VDD2 DOUT TAG Reader MLX90121 DOUT Close to pin 7 of MLX9 0121 DSYNC R16 imi ee E e N 10M ia E R e ear PD3 PC1 PD4 PCO GND ADC7 vcc ATmega8 GND GND AREF VCC ATmega amp 16AU ADC6 R7 2 1 CH ek 1K 100n D Q G jja 7 io a lt DoorMechanism Edge of the H board Wa i N R15 13 56MHZ 10M C19 C20 220F 22pF GND_uGN D E DIN KT ADC memory serial interface 1K C18 OnF o ARS 2 31AJ601 e Same D3 horizontal GND_ADC E gt y TP3 TE E LED G 5Vo C2 OUT N 2 c3 c4 c5 00nF 10uF Tant al 1 ut 30BQ060 GND Downloader l uF Tantal Soldered on a free PCB area of at least 1cm2 filled with vias SIIJEUIBYIS SHUNT L 1ohm T GND T Close to pin 4 of MLX90121 SHUN T3 ae 1ohm hi E E i GND_TX GN D_RX E E Close to Capa Var AN Button_Reset Edge of the board E E SHUNT2 l 1ohm GNE Close to pin 5 of ATmega8 SHUN T4 1ohm GND GND_ADC Close to pin 5 of ATmega8 TP_90121dg debug connector Thursday August 09 2007 GND connections Size A3 AGE Code DWG NO Rev 1 1 MELEX S Technologies SA RF90121DA 13 56MHz Tag Reader for door access applications Scale heet 1 of 1 Sexouuy FL SWAISAS pa DI63Ju DIUOIDA S
9. can also be considered as an advanced starting point for developers who want to build their own system meeting their specific requirements The software library FW121 facilitates the software development for MLX90121 transceiver and the programmer can use high level commands to communicate with the MLX90121 By this way they can concentrate on the management of the microcontroller and the upper level functionality of the application References source files FW_DA21_14A h FW_DA21_14A c FW_DA21_14A aps HwDefs h schematics See below Layout See below MLX90121 datasheet ATMega8 datasheet FW90121 Firmware description 13 56MHz RFID systems and antennas design guide 390129012103 Page 16 of 20 User Manual Rev 002 Apr 2008 c00 A9y 0LcL06c LOGE 8007 dy enuen 19asn 07 40 3 ed L1 as ET 47pF 100nF 1 2uH GND_TX R1 i g2 ANO BLM31AJ601SN1 oY C7 1 4 7uF Tantal cv2 2 8 12 5pF L3 L4 CB YY 680nH 15pF VDD1 9 GV 10 a xxpF 5 5 50pF 150pF 130pF R2 6 8uH GND_TX GND_TX VBS C12 XOUT 1P1 zi XIN 220pF Gnd R3 VS S2 Close to 100k T 8 Antenna GND uC XBUF connector x NC jE GND T RTB Gl X Z o ly 2K2 ML X90 RX o2 VSS3 NC fo 31AJ601 NIE GND_RX y R4 E 2 31 CH gst VDD3 DSYNC CK MODE DIN G O LZ 9 L E o o 5 R as 1K R5 2 7 1CH MOS 1K R6 2 1 CH SO 100 10
10. cececucucucusucuausenenenenenensnsnsnsnsasaeneueueueueuaenenenenenensnsnsneususuauaenesueusuauaeaenenenenens 8 9 4 ne eee 9 9 5 COCK OPA 9 CREE A PE PP AA 10 10 gig Ee ee ee ee 17 TTT 11 10 2 Practical AAA nanang x nga axnaaa gagn NX AXX 15 1i Rela ere H 15 pas Te T 16 TIA ias 17 VAIS A as 20 390129012103 Page 2 of 20 User Manual Rev 002 Apr 2008 DEMO90121DA N e lexi 5 RFID Door Access Demo User Manual Microelectronic Integrated Systems 3 Introduction You purchased a DEMO90121DA Thanks for choosing Melexis This demonstrator is a contactless door access solution based on the MLX90121 This document contains the instructions to use and evaluate the functions and the performances of this demonstrator All the necessary hardware is provided in the packaging box and the microcontroller on board is already programmed with the same firmware as the one present on the CD All that you need to do is to plug the cables and then to check visually the LED status when one or more of the tag cards are close to the antenna Should you want to start a development based on this demonstrator you will find in this document and on the CD all information like schematics board layout list of component firmware source C code and the related application note Please note that all this material is provided to support the use of the related Melexis product Duplication circulation or storage on data carriers in any manner for any other type of u
11. d 15014001 Certified 390129012103 Page 20 of 20 User Manual Rev 002 Apr 2008
12. e R1 resistor which connects the receiver part of the MLX90121 to the antenna It s value can vary from 1kQ up to 4 7KQ depending in the back modulation amplitude and the reading distance In this example 2 2kQ gives the best compromise Special care must be taken when using other values If R1 is too big the DC bias voltage and the back modulation signal seen by the receiver are not enough for correct reception If R1 is too small the DC bias voltage saturates the receiver input Modulation depth The 100 resistor R2 fixes the 10 modulation index for the 15014443B communication When using ISO14443A cards the R1 resistor is bypassed by the internal modulation transistor In case of OOK is used resistor can be kept here or not mounted 9 3 Microcontroller Connection to MLX90121 The microcontroller controls the MLX90121 manages the clock signals and interfaces the RFID function to the application i e the door lock mechanism Port D is used to connect the MLX90121 through the signals CK DSYNC DOUT DIN RTB and MODE DSYNC R16 Limiter2 5V 2m i Limiter Y QM xO gla La 0 L6 gt 10M C21 E and Dd Dl 5V L 5 a 22nF 1 4 RSSI Laa GND_uC_CK gI o gt Me 2 al PD4 N m J pe H Vec ATmega8 Gnn ae 0 100 T 61 GND armegas 16AU AREF yg T RSSI fil VCC ADC6 B Lc _ E a Yi C15 pone C16 Ee 100nF pone T R1415 13 56MHZ aa area gt gt GND_ADC 10M C19 C20 wo GND_ADC GND ADC E
13. e and without notice Therefore prior to designing this product into a system it is necessary to check with Melexis for current information This product is intended for use in normal commercial applications Applications requiring extended temperature range unusual environmental requirements or high reliability applications such as military medical life support or life sustaining equipment are specifically not recommended without additional processing by Melexis for each application The information furnished by Melexis is believed to be correct and accurate However Melexis shall not be liable to recipient or any third party for any damages including but not limited to personal injury property damage loss of profits loss of use interrupt of business or indirect special incidental or consequential damages of any kind in connection with or arising out of the furnishing performance or use of the technical data herein No obligation or liability to recipient or any third party shall arise or flow out of Melexis rendering of technical or other services 2007 Melexis NV All rights reserved For the latest version of this document go to our website at www melexis com Or for additional information contact Melexis Direct America Europe Africa Asia Asia phone 1 603 223 2362 Phone 32 1367 0495 Phone 32 1367 0495 E mail sales_usa melexis com E mail sales_europe melexis com E mail sales_asia melexis com ISO TS 16949 an
14. f the codes are not lost 6 The average current consumption is 0 4mA no change of the antenna load 390129012103 Page 6 of 20 User Manual Rev 002 Apr 2008 DEMO90121DA N e lexi 5 RFID Door Access Demo User Manual Microelectronic Integrated Systems 9 Hardware 9 1 General The DEMO90121DA is built around the MLX90121 RFID transceiver front end and the 8bit microcontroller Atmel ATMega8 The MLX90121 handles the air interface in transmission and in reception It drives the antenna through its Class E power driver in order to generate the HF magnetic field and modulation according to the protocol and command generated by the microcontroller It demodulates the answer from the tag and provides digital signals to the microcontroller The ATMega8 runs the protocol and the application software The board has three interfaces one for the door opening mecanism a SPI connection for the uC programmation and a debug connector It embeds a reset button clock and power management functions and can be powered from a battery 9 2 RF part Emission The MLX90121 integrates a class E driver capable of providing up to 200mW to the antenna The Class E driver TX pin is connected to the antenna through a resonant load and an adapter circuit In order to give users the choice to connect to a variety of different antennas the transceiver output is matched to 500 impedance The adaptation impedance is composed by L2 C6 resonant load CV2 C8 L
15. icrocontroller and MLX90121 in power down h and L microcontroller active and MLX90121 in power down l and tz wake up phase of MLX90121 idle mode and microcontroller activ lz and tz MLX90121 in transmit mode and microcontroller active l4 and t4 As shown in the table MLX90121 is in power down most of the time t 288ms The transmitter is on for very short time if the RSSI signal didn t change since last loop then the microcontroller puts MLX90121 in power down If the RSSI signal changed significantly MLX90121 sends the inventory commands and is afterwards put in power down mode t increases to tens of ms The microcontroller will continue to check the inventory results and eventually open the door lock or store the new codes in EEPROM 390129012103 Page 15 of 20 User Manual Rev 002 Apr 2008 DEMO90121DA N e lexi 5 RFID Door Access Demo User Manual Microelectronic Integrated Systems Using four alkaline AA batteries to supply the application boarda DEMO90121DA with 10 actuations 15014443A tag cards passed through the 13 56MHz field per day the voltage variation looks like depicted in Figure 14 VBat in time 24 00 00 48 00 00 72 00 00 96 00 00 120 00 00 144 00 00 Figure 14 Battery voltage variation during a few days 12 Conclusion The DEMO90121DA is an example of a small cost effective and simple control module for door access based on the Melexis 13 56MHz transceiver MLX90121 It
16. ler is awake about 0 98 of the time and the transmitter 0 25 of the time The measured average supply current is below 0 41mA The two layer PCB has several ground planes that are connected one to each other by shunts that can be substituted by some small value resistors 0805 case in order to reduce noise propagation between the different functional blocks 9 5 Clock The unique clock source reference is one quartz resonator of 13 56MHz connected to the microcontroller In order to reduce the component count and the bill of material the Xtal is shared and the clock output PB7 from the microcontroller is fed to the clock input XIN of the transceiver 390129012103 Page 9 of 20 User Manual Rev 002 Apr 2008 DEMO90121DA N e lexi 5 RFID Door Access Demo User Manual Microelectronic Integrated Systems 9 6 Interface There are additional components that interface the microcontroller to the external world An SPI interface which can be used for microcontroller programming a reset switch for initialization of the system a debug connector for the developer to verify the firmware changes and the functional interface composed of 2 LEDs 2 digital level inputs for two position sensors Limiter1 and Limiter2 and one low power digital level output LockMotor MI 2 DoorMechanism Edge of the board Button_Reset Edge of the board GND uC GND uC uC reset circuit GND uc TP_90121dig Door Mechanism Sig
17. m GND uGND uC 22pF 22pF GND uGND uC GND_ADC DIN K TP3 B RIB MISO 7 GND uC MODE OSI Gnd Y 01010 EE al Bad Card s 1 kMotor UC ADC memory serial interface gas GND ADC Figure 6 Microcontroller block Clock A 13 56MHz quartz crystal oscillator is connected between PB6 and PB7 for the generation of the clock The resistor R12 is used to attenuate the fast transients generated by the clock connection between MLX90121 and ATMega8 Wakeup Cycles In order to reduce the power consumption the microcontroller alternates sleep and wakeup modes This cycle is generated by means of a RC circuit composed of R16 and C21 connected on PD3 The time constant given by the RC enables an interrupt INT after about 280ms The precision is given by the tolerances of R16 and C21 Programming and development The microcontroller can be programmed onboard using the SPI interface This serial interface associated with adequate hardware and software allows read and write access to all memory blocks of the microcontroller This is useful for firmware updates or changes in case of adaptation to specific requirement 390129012103 Page 8 of 20 User Manual Rev 002 Apr 2008 DEMO90121DA N e lexi 5 RFID Door Access Demo User Manual Microelectronic Integrated Systems Code size The firmware used in the DEMO90121DA requires 5 2KBytes of program FLASH of the ATMega8 The microcontroller ATMega8 can be substituted by other pin compatible ATME
18. nals debug connector Figure 8 Microcontroller interface to external world Developers should add an adequate power buffer to be able to drive the door lock motor or electromagnet 390129012103 Page 10 of 20 User Manual Rev 002 Apr 2008 DEMO90121DA N e lexi 5 RFID Door Access Demo User Manual Microelectronic Integrated Systems 10 Firmware 10 1 Structure The firmware developed for the DEMO90121DA provides master tag programming anticollision handling and tag detection as the basic service functions of the door lock application The flowchart below shows the main structure of the firmware Configure hardware Read master tag ID l Check han many codes are in EEF RO hd same 2 Y different Read tag IDs Han many walid tags One hore than 1 hlaster tag Yes Check limiters door opened and handle pushed Endless loop Mone Open door Vv Store nan tag IDs in Other EEFR O tl Ho Store current RSSI walue Sleep for 300 me Wake up Figure 9 Main flowchart of the DEMO90121DA firmware After power on or reset the microcontroller sends a read command to the first tag in the field and stores its ID in memory This will become the ID of the master tag for the application In the event of absence of tag in the field the codes previously stored remain valid including the
19. right Put the card with the Master Key privilege card A together with another card card B close to the antenna LEDs BA and BS will be on together tag detected then BY alone will blink two times two 1SO14443A cards are detected then BS alone will blink two times two valid codes are stored in microcontroller memory This means that right to open the door is transferred from the card A to the card B The card B UID is added as Valid Key card one 390129012103 Page 5 of 20 User Manual Rev 002 Apr 2008 DEMO90121DA N e lex S RFID Door Access Demo User Manual Microelectronic Integrated Systems 8 Observations 1 Reading range of the DEMO90121DA is about 10cm 2 Tag detection is made by change of the antenna field load compared to previous cycle one cycle is about 300ms or longer Therefore the LEDs BB and DI blinking once together indicating in this way the field change It could occur that approaching objects to the antenna generates a tag detection indication 3 When one or more 15014443 tag cards are already in the field just after the tag detection indication BA will blink indicating how many cards it detected once if only one card twice if it detected two cards etc 4 In order to reduce a too strong coupling between tag cards fan them a little when approaching two or more to the antenna 5 The valid tag codes are stored in the non volatile memory of the microcontroller of the DEMO90121DA so after a power of
20. scribes the performance of the demo and explains its hardware and software One can see this document as a starting point for building their own access control system by adapting the functions and performances to their specific requirements 2 Related Melexis Products MLX90121 13 56MHZz transceiver Note 1 The device is for demonstration purpose and has not been tested for compliance with FCC ETSI or any other regulations Note 2 The MLX90121 is limited to positive temperatures in the 1S014443A mode Therefore and without any changes this demonstrator is suitable for indoor applications Should you require outdoor operations you may modify its firmware to use the demonstrator with IS014443B cards 390129012103 Rev 002 Page 1 of 20 User Manual Apr 2008 DEMO90121DA N e lexi 5 RFID Door Access Demo User Manual Microelectronic Integrated Systems Table of Contents PC o o A A E ANENE NE A I ON AE E E AE A A S N ANAA A A E T 1 2 Related Melexis Products 1sccccccnccccncceecccnsccnnccnneccncccenscanecnnecnansnenscansenesensscnnscnassnansaensennscnnsseansennssnaess 1 A l re TTT 3 A 3 LR elese rle TT 5 O Working elel 5 F arre ieaie and UA es a ee ce ea ees ee eee scenes 5 Tid OV SIGMA MINT IANZ ATION AA oo o o E E E N 5 Tae OO TAG He COOL oa 5 Ta Bg aki AEL ene ne E ee eo eS gee ae 5 BOD SOP V ALOIS aaa 6 9 HardWare A a 7 9 1 CONO nr NAAA nannan 7 DR PIN PO 7 9 3 Microcontrolleft oaceac cuca cncncncececn
21. se are not authorized by Melexis unless specific agreement 4 Box Content You will find in the box the following components e 1 RFID reader board ar Y AAA Ji WE i S LED D3 Alla Elie y i O Tay E SIT PINDHO e gt E AS a a lt Battery cable connector kidt af JA f l 53 E saf Antenna connector sd d MS gt LED D4 eT SS H oa 9 K Q Figure 1 RFID reader board Top side e 1 antenna board ANT V1 0 hug 2007 Melex Antenna connector es Figure 2 Antenna ANT2_0 390129012103 Page 3 of 20 User Manual Rev 002 Apr 2008 DEMO90121DA N e lexi 5 RFID Door Access Demo User Manual Microelectronic Integrated Systems e 3 tag cards as GATEMAN MELEXIS RFID DEMO 2 o 3 a TEF E E EC ne GATEMAN MELEXIS RFID DEMO 1 Figure 3 ISO14443A tag cards e 9V battery and battery cable y Battery Battery connector Connector to reader board Figure 4 The 9V battery and the power supply cable e 1 CD with the firmware and documentation The delivered CD contains the complete documentation of the hardware and firmware for DEMO90121DA User Manual Datasheet MLX90121 Source Code of the firmware written in C flavor AVR gcc Hex file of the firmware Schematics of the board ORCAD 9 2 file Layout of the board GERBER files Bill of materials of the board e 1 User Manual on paper this document e 1 Box Content on paper 390129012103
22. tag is present the device will read its UID store it and associate it with the Master Key privilege and delete other UID from memory e lf two or more tags are present nothing changes in the configuration The UIDs previously stored in the memory are kept As this device could be an example for battery powered access control system the power consumption was optimized Therefore the device is running in low power mode the main part of the time and switch on its tag detection function for few instant In absence of tag the device enters back in low power In the opposite case it starts an RFID communication and the door access function 7 Functions and use 7 1 System initialization Place a card on the antenna Press BUTTON1 reset of the DEMO90121DA and check that the LEDs D8 and afterwards BA start to blink rapidly microcontroller registers tag card nr 1 as master card 7 2 Opening the door The device executes this operation in 3 steps tag detection opening I5SO14443A communication reading and checking the UID Approach any kind of card near to the antenna Then i and D3 will be on together indicating that a tag is detected If this card is compliant to 15O14443A then BA will blink alone once In the opposite case nothing more happens If this card has any access privilege Master or Valid Key then D3 will blink alone once meaning that the card is recognized as valid card In other case nothing more happens 7 3 Transfer access
23. tering is conditioned by the state of the two limiters door lock should be opened and door handle pushed If only the master tag is in the field the list stays as is and the command to open the door is sent See Figure 9 In order to reduce the success rate of code scan hacking devices the door lock can be opened in the presence of only one valid tag in the field This applies to the master tag too A closed door limit switch condition restricts the firmware to access the function to open the door and for only one valid tag present in the field See Figure 9 390129012103 Page 12 of 20 User Manual Rev 002 Apr 2008 DEMO90121DA N e lexi 5 RFID Door Access Demo User Manual Microelectronic Integrated Systems After a hardware reset there is the possibility to clean the list of all valid codes and redefine the master tag code See Figure 11 Start Inventory Get ID of tag in the field tag Response Yes Ho Vo more tags in the field es Store tag ID Increment index of tag IDs One tag in the filed Yes Store master tag ID in EEPROM address Ch v Reset in EEPROM the other tag IDs master tag ID Figure 11 Reading the master tag code at reset Observations The valid tag codes can be up to 12 bytes long 96bits The algorithm can be modified in order to comply with the
24. the microcontroller IO ports timers ADC and watch dog and the MLX90121 transceiver registers are configured for the 15014443A protocol as described in the MLX90121 datasheet The firmware was developed using GCC under AVR Studio 4 The firmware can be loaded in the microcontroller using the SPI interface connected to a STK500 STK300 AVRISP mell module or similar driven by appropriate software AVR Studio PonyProg2000 etc FW_DA21_14A c and FW_DA21_14A h contain the firmware specific gcc code and the functions prototypes HwDefs h describes the hardware input output pins etc The file FW_DA21_14A aps is the AVR Studio 4 project file 11 Power consumption The DEMO90121DA is built for running on battery power and the current consumption is therefore optimized The picture below Figure 13 shows the typical current consumption variation during one cycle loop Figure 13 Supply current variation No tag in field The average current consumption is about 0 41mA giving 100 days autonomy using a 1000mAh battery This value is of course dependant on the number of access events and is deeply impacted by the consumption of the door lock mecanism Special care should be taken for the choice of RSSI threshold dVrssi parameter If its value is too small noise can make the device start inventory attempts without tags in proximity Current consumption values Working phase parameters Current Period mA ms both m
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