RFID - Elektor

More documents

Recommendations

Info

9 Elektor RFID Projects tion. The received data bytes are automatically written to the FIFO buffer by the contactless UART. Because only one FIFO is available for both reading and writing, the card command is overwritten. Since all communication is based on the master-slave principle, overwriting the command data presents no problems. The entire procedure for contactless communication is controlled solely by the MF RC522’s control, configuration and status registers. 9.1.1 Elektor RFID Reader Library: MF RC522 The RC522.ReadSFR() and RC522.WriteSFR() methods in the Elektor RFID Reader library enable direct access to the MF RC522 registers. In this case, the reader firmware’s function is reduced to that of a special USB-to-I2C converter for controlling the MF RC522 UART. Table 9.1. Methods available for direct control of the MF RC522 SFRs. Method byte ReadSFR(byte sfrAddr); void WriteSFR(byte sfrAddr, byte sfrValue) Description Returns the value of the given MF RC522 special function register (SFR). Writes the sfrValue parameter to the given MF RC522 SFR. With the help of these two methods, it is possible to develop and test parts of the reader firmware directly on the PC. This eliminates time-consuming microcontroller programming (flashing). All of the reader IC’s analog parameters can be changed by configuring the corresponding SFR. Tuning the antenna and optimizing the reader’s range requires repeated changing of the MF RC522’s analog parameters, and thus the repeated updating of the corresponding register values. Using the conventional approach, the firmware would have to be updated for every new iteration. It is much more efficient in this case to adjust the register values using a PC program (e.g. a Smart Card Magic.Net script) and then perform the RF measurements. It’s only necessary to load a modified version of the reader firmware into flash memory after successful analog performance optimization. copyright Elektor 9.1.2 Program Examples 9.1.2.1 Changing the RF Parameter Configuration This example shows how one overwrites the modulator and demodulator default values, for test purposes. The default values are automatically restored from the reader firmware when power is supplied to the RFID Reader. Note The MF RC522 offers the possibility of connecting different antenna configurations. Therefore, you should not change the Elektor RFID Reader MF RC522 SFRs that define the output driver circuit. Otherwise, in extreme cases, this could lead to a short circuit that could destroy the reader IC or other circuit components. 386
Programming the MF RC522 Reader IC 9.1 Listing 9.1. Excerpt from RC522RfParameterConfig.cs. (from www.smartcard-magic. net/smart-card-magic-net/) ▌▌ ▌▌ ▌▌ ▌ ▌ ▌▌ ▌ ▌ ▌ ▌ ▌ ▌ ▌ ▌ ▌ ▌ ▌ ▌ ▌ ▌ ▌ ▌ ▌ ▌ ▌ ▌ ▌ ▌ ▌ ▌ ▌ ▌ ▌ ▌ ▌ ▌ ▌ using System; using GS.Util.Hex; using GS.ElektorReader; using GS.ISO14443_Reader; namespace GS.ElektorRfidReader ▌ { ▌ class RC522RfParameterConfig ▌ { ▌ const byte RxThresholdReg = 0x18; // selects threshold for the bit decoder ▌ const byte DemodReg = 0x19; // defines demodulator settings ▌ const byte ModWidthReg = 0x24; // controls the ModWidth setting ▌ const byte RFCfgReg = 0x26; // configures the receiver gain ▌ public static void Main(MainForm script, string[] args) ▌ { ▌ ElektorISO14443Reader reader = new ElektorISO14443Reader(); ▌ try ▌ { ▌ reader.OpenPort(); ▌ // RF parameter configuration ▌ reader.RC522.WriteSFR(RxThresholdReg, 0x55); // Bit decoder threshold ▌ // MinLevel, CollLevel ▌ reader.RC522.WriteSFR(DemodReg, 0x4D); // Demodulator Setting ▌ reader.RC522.WriteSFR(ModWidthReg, 0x26); // Modulation width ▌ reader.RC522.WriteSFR(RFCfgReg, 0x59); // Receiver Gain ▌ int ret; ▌ Console.WriteLine(“Wait for new Card...”); ▌ do ▌ { ▌ ret = reader.ActivateCard(RequestCmd.REQA); ▌ } ▌ while((ReaderStatus)ret != ReaderStatus.OK); copyright Elektor Figure 9.2. Any of the MF RC522 parameters can be changed using a script. 9.1.2.2 MF RC522 SFR Programming — Card Activation The programming of the MF RC522 is presented with a card activation example. In this implementation, the bit frame anti-collision algorithm is omitted for clarity. Should more 387
Page 1 and 2: copyright Elektor
Page 3 and 4: Contents 2.1.4 Part 4: communicatio
Page 5 and 6: Contents 5 Introduction to Cards an
Page 7 and 8: Contents 7.6.2.2 A Scripting Tool o
Page 9 and 10: Contents 8.8.1.1 Class Byte (CLA) .
Page 11 and 12: Preface Dr. Thomas Wille RFID techn
Page 13 and 14: 5 Introduction to Cards and Tags Re
Page 15 and 16: Overview 5.1 A typical application
Page 17 and 18: MIFARE 5.2 MIFARE Classic chip and
Page 19 and 20: 8 Cards and Tags in Application 8.1
Page 21: 9 Elektor RFID Projects Gerhard H.
Page 25: copyright Elektor

RFID - Elektor

Create successful ePaper yourself

Delete template?

Save as template?