ATA559001-6DSY Atmel, ATA559001-6DSY Datasheet - Page 85

• Manufacturer Part Number: ATA559001-6DSY
• Description: RF Wireless Misc UHF (1k bit r/w anti-collision)
• Manufacturer: Atmel

Specifications of ATA559001-6DSY

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

13.3
13.4
13.5
13.5.1
13.5.2
4817C–RFID–03/07
CRC Calculation During Anticollision and Group Selection
CRC Condition
Set and Reset Conditions of Status1 Register Flags
Common
Set Condition of Pre_select
The arbitration works bit by bit. The reader itself defines the selected priority by the PIE signal
during the arbitration. The timing reference is defined in the return link header. After each bit, the
tag decides whether the arbitration is won or lost. If the arbitration is lost, the tag does not
change the state of the modulator, meaning that it no longer modulates the antenna impedance.
The decision is under control of the reader station because the reader observes the backscat-
tered modulation during the bit, and can therefore decide which data is backscattered by the tag.
The control mechanism is based on the timing information between two notches and the refer-
ence time transmitted during the header. If the time is less than the reference length (2nd
symbol of the return header), then the tag which has backscattered a “0” has won the arbitration.
If this time is longer, the tag which has backscattered the “1” status has won otherwise lost.
Note:
The tag calculates a CRC over the command, the parameter, and the arbitration field. The
header and the EOT symbols are not part of the calculation. During arbitration, the calculation is
based on the internal values of the memory and, if activated, over the random value.
The flag nCRC_adapt in the parameter field decides the function of the CRC communication.
If it is set to “1”, the tag expects the inverted 16-bit CRC information from the reader to decide if
the result of the arbitration will be accepted.
If it is set to “0”, the tag backscatters the inverted value. The tag backscatters the CRC in a loop
(rot_l), and expects from the reader a “0” for each bit (shorter than the second symbol of the
return header). If the tag detects a “1”, it sets an arbitration_lost flag internally, and stops back-
scattering. No status register flag of register status1 will be set.
Note:
Set and reset conditions are based on the result of the arbitration over the data field in conjunc-
tion with the result of the CRC field. If the tag receives an error during the CRC field, the result of
the arbitration over the data field will be ignored.
• If the pre_select flag was set and a power-on reset has occurred (reload function after POR)
• If a group command was in use, the tag has won the arbitration, and the tag did not receive
an error during CRC
The time for a logical 1 shall be less than the time for the EOF.
It is enough to send one logical 1 (nCRC_adapt = 1). Directly following, the reader can send the
EOF sequence.
ATA5590
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