EM4069
EM4169
EM4069 Modes of operation
IDLE
RF-field detected
INIT
The EM4069 additionally holds a unique 64 bit read only
identification code, which can be accessed by using the
Read ROM command.
Manchester encoding
One bit period lasts 64 (or 32) field frequency periods
(512 (or 256)
µs
at 125 kHz). The Manchester coding
shows a transition from ON to OFF or from OFF to ON in
the middle of bit period. At the transition from logic bit “1”
to logic bit “0” or logic bit “0” to logic bit “1” the phase
change. Value "high" of data stream presented below
represents modulator switch OFF, "low" represents
switch ON (see figure 6a).
Reset
Command
EEPROM Read Mode
Sync-Pattern
Command finished
Bi-phase encoding
Command State
Fig. 5
Read Mode
The EM4069 holds 128 bits of user EEPROM. These 128
bits are cyclically read out by default. Using the write
command, the EEPROM words can be modified. The
EEPROM contains an additional configuration word used
to protect writing in the EEPROM
One bit period lasts 64 (or 32) field frequency periods
(512 (or 256)
µs
at 125 kHz). The BI-phase coding shows
a transition from ON to OFF or from OFF to ON in the
middle of a bit period when the data bit is a logical “0”. A
logical bit set to “1” will keep its ON or OFF state for the
whole bit period. There is always a transition from ON to
OFF or from OFF to ON at the beginning of a bit period.
The picture below shows part of a data stream. Value
“high” of data stream represents modulator load OFF,
“low” represents modulator load ON (see figure 6b).
Manchester encoding
Binary data
Memory output
Modulator control
X
1
1
1
1
1
1
1
1
1
0
1
0
1
0
0
0
1
1
0
Modulation control “low” means high current
Fig. 6a
Bi-phase encoding
Binary data
Memory output
Modulator control
0
1
1
0
1
0
0
1
Modulation control “low” means high current
Fig. 6b
Copyright
2003, EM Microelectronic-Marin SA
5
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EMMICRO [ EM MICROELECTRONIC - MARIN SA ]
