Proximity Communication Interface Implementation Specifications

12.1.4.2 ATQA-Answer To Request
(1) Basic Specifications
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After a REQA Command is transmitted by the PCD, all PICCs in the IDLE State shall respond
synchronously with answer to request signal (ATQA).
After a WUPA Command is transmitted by the PCD, all PICCs in the IDLE or HALT State shall
respond synchronously with answer to request signal (ATQA).
The PCD shall detect any collision that may occur when multiple PICCs respond.
An example is given in "12.3 Communication Example Type A".
(a) Coding of ATQA
Encoding of an answer to request signal (ATQA) is shown in "Table 12.1-3 Coding of ATQA".
Table 12.1-3 Coding of ATQA
MSB LSB
b16 b15 b14 b13 b12 b11 b10 b9 b8 b7 b6 b5 b4 b3 b2 b1
(0000)b Proprietary coding UID size R Bit frame anticollision
Other values are RFU
bit frame F
U