EM4205-EM4305
Return Link Encoder
(Communication from Tag to Reader)
transmitted, the output is High during the first half of the
bit period and is Low during the second half of the bit
period.
In read mode, the NRZ data coming from the EEPROM
flows (Default read or answer to Read Word command)
through the Encoder before it is transferred to the
Modulator. A logic 1 (high) means the Modulator is on.
Bi-phase:
In Bi-phase coding, there is a transition from High to Low
or from Low to High at the beginning of each bit period.
When a logic 0 is transmitted there is an additional
transition in the middle of the bit period. When a logic 1 is
transmitted there is no transition in the middle of bit
period.
Manchester
In Manchester coding, there is a transition from High to
Low or from Low to High in the middle of the bit period.
When a logic 0 is transmitted, the output is Low during
the first half of the bit period and is High during the
second half of the bit period. When a logic 1 is
NRZ in
Manchester
Bi-phase
Figure 14
Examples of possible configurations
Pigeon Races: Manchester – RF/64 mode
In pigeon races, the EM4205/4305 uses a Manchester data encoding. The duration of a data bit corresponds to 64 periods
of the magnetic field (data rate of RF/64).
Pigeon configuration bit (Co25) has to be set to logic 1.
The pigeon code is programmed in Words 5, 6 and 7. The EM4205/4305 starts to read the 32 bits of Word 5, then reads the
16 LSB bits of Word 6 and continues with the 16 LSB bits of Word 7.
The pigeon code has to be programmed as following:
Word 5: 32 first bits which corresponds to bit 0 up to bit 31 of the pigeon code
Word 6: 16 LSB bits which corresponds to bit 32 up to bit 47 of the pigeon code
Word 7: 16 LSB bits which corresponds to bit 48 up to bit 63 of the pigeon code
This data structure permits to lock 48 bits of the pigeon code and allows the modification of 16 bits before the race.
FDX-B: Livestock Applications
In FDX-B mode, the EM4205/4305 sends back to the reader, its memory contents from word 5 up to word 8 (128 bits) using
a bi-phase data encoding and a data rate of RF/32. The duration of one bit is 32 magnetic field periods.
13
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4205-4305-DS-01.doc, Version 4.0, 22-Oct-13
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