V4070 EM Microelectronic, V4070 Datasheet - Page 8

• Manufacturer Part Number: V4070
• Description: Crypto Contactless Identification Device
• Manufacturer: EM Microelectronic

Communication from Transponder to the Transceiver ( READ MODE)
The V4070 modulates the amplitude of the RF field to transmit data to the transceiver. The data is output
serially from the EEPROM and manchester encoded.
The V4070 uses different patterns to send status information to the transceiver. Their structure cannot be
confused with a bit pattern sequence. These patterns are the Listen Window (LIW) to inform the transceiver that
data can be accepted, the Acknowledge (ACK) indicating proper communication and end of EEPROM write,
and the No Acknowledge (NAK) when something is wrong.
Communication from the Transceiver to the Trans-
ponder (RECEIVE MODE)
The V4070 can be switched to the Receive Mode ONLY
DURING A LISTEN WINDOW. The Transceiver is syn-
chronized with the incomming data from the trans-
ponder. During the phase when the chip has its modu-
lator “ON” (32 periods of RF), the transceiver has to
send a bit “0”. At reception of the first “0”, the chip
stops immidiately the LIW sequence and expects then
another bit “0” to switch to receive mode. The trans-
ceiver and the chip are now synchronized and further
data is sent with a bit rate of 32 periods of the RF field.
The V4070 turns “ON” its modulator at the beginning
of each frame of 32 clock periods corresponding to
one bit. To send a logic “1” bit, the transceiver contin-
ues to send clocks without modulation. After 16 clocks,
the modulation device of the V4070 is turned “OFF”
allowing recharge of the internal supply capacitor. To
send a logic “0” bit, the transceiver stops sending clocks
All numbers represent number of periods of RF field
16 16
EM MICROELECTRONIC-MARIN SA
64
LIW
32
32
Measured on
Coded Data
Data from
EEPROM
the COIL
32 periods of
RF field
1 bit
16 16
16 periods
48
ACK
1 bit
(100% modulation) during the first half of a bit period
(first 16 periods). The transceiver must not turn “OFF”
the field earlier than clock 1 of a bit period. It is recom-
mended to turn “OFF” the field after 4 clocks of the bit
period. The field is stopped from clock 5 to 16 of the
bit period, and then turned “ON” again for the remain-
ing 16 periods.
To ensure synchronisation between the transceiver and
the transponder, a logic bit set to “0” has to be trans-
mitted at regular intervals. The RM pattern consists of
two bits set to “0” thus allowing initial synchronisation.
While the transceiver is sending data to the trans-
ponder, two different modulations will be observed on
both coils. During the first 16 clocks of a bit period, the
V4070 is switching “ON” its modulation device caus-
ing a modulation of the RF field. This modulation can
also be observed on the transceiver’s coil. The trans-
ceiver to send a bit “0” will switch “OFF” the field, and
this 100% modulation will be observed on the trans-
ponder coil.
16
48
1 bit
16
Figure 15
1 bit
16 16
48
NAK
V4070
16
32
Figure 16
16 16
8