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EM4069B5WP7E Datasheet(PDF) 9 Page - EM Microelectronic - MARIN SA |
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EM4069B5WP7E Datasheet(HTML) 9 Page - EM Microelectronic - MARIN SA |
9 / 15 page EM4069 EM4169 Copyright 2003, EM Microelectronic-Marin SA 9 www.emmicroelectronic.com The bit pattern of the Write configuration word command is compatible to Write Word command: 1101 0011 [8 bits protecting 8 words] [8 bits don’t care] [8 bit CRC] 8 bits protecting 8 words: Bit first sent in is protecting word 0, the second bit protects word 1 and so on. 8 bits don’t care: Any 8-bit pattern, all 0 pattern is not suggested for power supply reasons. CRC has to be correct including also don’t care bits. Example of Write Configuration Word command: D3 02 55 2F (hex) The above command (1101 0011) will protect word 6 (0000 0010) from being written. in Sync. wcw out Read Read tWee 1ms Fig. 11 If later on, word 1 has to be protected, the protection bit of already protected word 6 has to be set to logic 1 again. The new command will have to be sent with the following protection bits: 0100 0010. Read Configuration word Command To enter this command the IC has to be in default mode (read EEPROM bits). After execution of this command the IC will cyclically read 128 bits. 16 of them will represent the configuration word the rest is 0. It is suggested that don’t care bits of configuration word are programmed with some pattern which will be easy to recognize during read out. Command Timing for 8-bit command While IC is in Read mode it is sampling the peak level of coil voltage (during the time modulator switch is ON) once every bit period. The peak to peak value is compared with an internal reference in order to get a one-bit information (high field or low field). The measured level is compared with previous samples in order to detect whether there is a reader-induced modulation present on the magnetic field. Commands are accepted in the range where normal field (100% strength) is higher than internal reference (considered as high field) and modulated field is lower than internal reference (considered as low field). An 65% modulation on the reader signal is proposed (high field 100%, low field 20%). When the synchronization pattern of modulation on magnetic field is detected (Command Envelope) the EM4069 waits for a Start Bit (SB). If the start bit is detected before tS3 time-out is expired, the Command Processing mode is entered. Eight command bits are serially entered. After the last bit was shifted, the 8-bit pattern is compared to one of the 5 possible commands. In the case one of the commands is recognized the appropriate action is performed otherwise the IC returns in Read mode. Detection of Command Envelope The Peak Detector performs the measurement once every bit period. The Peak Detector circuit compares the peak value of voltage on the coil to the internal voltage reference. The result of comparison is one bit of information, which tells to Control Logic whether the field is strong (HIGH field) or weak (LOW field). The Peak Detector circuit has a built-in hysteresis of typically 100mV which prevents unwanted Envelope detection in field strength which is at the level of the Detector threshold. Detection of Start Bit (SB) and Command Word After the Synchronization pattern Envelope was detected, the EM4069 is sampling the incoming signal at a TRDB /8 rate. The start bit is accepted as valid when three consecutive samples are LOW. Duration of start bit (version 64 clocks/bit) and following command bits are expected to be 512 µs (same as one bit period in read mode). In the version 32 clocks/bit, the duration is 256 µs When the start bit is detected, the Control Logic starts switching Modulator load OFF and ON (First half of bit period OFF and second half of bit period ON) to assure enough power for operation of the IC. Samples of incoming bits are taken during the time the modulator load is ON (connected). The command, address, data and CRC bits are sent in non coded form (NRZ), reader induced high field (non modulated) corresponds to logic one, low field (modulated) to logic zero. |
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