ATA559001-DBW Atmel, ATA559001-DBW Datasheet - Page 69

• Manufacturer Part Number: ATA559001-DBW
• Description: RF Wireless Misc UHF (1kbit r/w anti- collis. Ni-Au)
• Manufacturer: Atmel

Specifications of ATA559001-DBW

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

9.8
4817C–RFID–03/07
Adaptive Return Link CRC Field
During return link operation, ATA5590 supports an adaptive CRC field.
In the case of anticollision and group-selection commands, the function must be enabled by a bit
in the parameter field. The control bit is called nCRC_adapt. If this bit is set to “0”, the CRC has
a fixed length. If the bit is set to “1”, the bit count of the CRC is under the control of the reader.
To activate this mode for all the other commands, the reader has to send an EOF symbol in the
LSB position of the data frame. After receiving the EOF symbol, the tag backscatters the CRC
value in a loop.
The tag observes the data stream coming from the reader during this adaptive period. The refer-
ence for decoding this acknowledgement is the 2nd symbol of the return link header. A time
shorter than this reference results in a “0”, otherwise in a “1”.
A timing longer than the 4th symbol (EOF reference) results in an EOF.
The tag expects at minimum one acknowledge bit; then a new header can follow.
ATA5590 checks the PIE information transmitted by the reader for anticollision and group-selec-
tion commands. A “0” is interpreted as a pass, and a “1” is interpreted as a fail. An EOF is
interpreted as the end of the CRC field.
After receiving the second EOF symbol, the tag can change the status1 register contents.
Notes:
Figure 9-4.
The CRC field can also be adaptive for commands other than anticollision or group selection. If
the reader transfers an EOF symbol instead of the last data bit, the CRC field is also adaptive
after reception of this bit.
Note:
During the adaptive CRC field, the tag observes the data stream coming from the reader. The
loop function is active as long as the tag receives a “0”. If the tag receives a “1”, it expects a new
return link header. If an EOF is received, it expects an additional EOF to generate the EOT.
1. The data information which was backscattered during the EOF symbol is not part of the CRC
2. The CRC frame has a minimum length of one bit.
The data which is backscattered during the EOF field is not part of the CRC calculation.
calculation.
Reader
Adaptive CRC Field During Group-selection and Anticollision Procedures
Tag
Arbitration field
Arbitration field
CRC calculation
ignored
data(n)
EOF
adaptive CRC
loop
CRC
EOF
EOF
EOF
EOF
ATA5590
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