ISO IEC 14443-3:2018 pdf free.Cards and security devices for personal identification一Contactless proximity objects一 Part 3: Initialization and anticollision.
5 General requirements
5.1 Alternating P1CC and PCD support (PXD)
A proximity extended device (PXD) shall alternately support P1CC requirements (P1CC Mode) and PCD requirements (PCD Mode).
The alternation between the P1CC Mode and the PCD Mode may be either automatic or a Mode (P1CC Mode or PCD Mode) may be explicitly selected by the user.
The P1CC Mode and the PCD Mode are defined as P1CC and PCD in the ISO/IEC 14443 series of standards. The automatic alternation is defined as follows:
— the PXD shall alternate between the P1CC Mode and the PCD Mode with maximum cycle time = 1 s and shall stay in P1CC Mode (ready for receiving REQA/WUPA or REQB/WUPB commands, except for the first 5 ms) longer than in PCD Mode (generating operating field), until a communication to either a P1CC, a PCD or another PXD is established;
— the PXD shall randomly set the P1CC Mode duration for each cycle to a value chosen from a set of at least two different values differing by at least tdff = 5 ms between each of them;
— in P1CC Mode, after reception of a valid REQA/WUPA or REQB/WUPB command, the PXD shall not go in PCD Mode before a POWER-OFF state;
— when leaving the PCD Mode after processing of a P1CC (or a PXD in P1CC mode), the PXD shall resume its automatic mode alternation with the P1CC Mode first.
The PXD may check the presence of external operating field to decide not to enter PCD Mode, i.e. to stay in P1CC Mode for a further random P1CC Mode duration.
The detection of the removal of a P1CC (or PXD in P1CC Mode) should be done by a P1CC presence check method without switching off the operating field to keep the same UID/PUPI and to avoid PXD entering the PCD Mode.
5.2 Alternating between Type A and Type B commands
5.2.1 Polling
In order to detect PICCs which are in the operating field, the PCD shall send repeated request commands. The PCD shall send REQA (or WUPA) and REQB (or WUPB) in any sequence using an equal or configurable duty cycle when polling Type A and Type B. In addition, the PCD may send other commands as described in Annex C.
7.2 CRC_B
A frame shall only be considered correct ifit is received with a valid CRC_B value.
The frame CRC_B is a function of k data bits, which consist of all the data bits in the frame, excluding start bits, stop bits, delays between bytes, SOF and EOF, and the CRC_B Itself. Since data is encoded in bytes, the number of bits k is a multiple of 8.
For error checking, the two CRC_B bytes are included in the frame, after the data bits and before the EOF. The CRC_B shall be as defined in ISO/IEC 13239. The initial register content shall be all ones: ‘FFFF’. For examples, refer to Annex B.
7.3 Anticollision sequence
An anticollision sequence is managed by the PCD through a set of commands detailed in this subclause.
The PCD is the master of the communication with one or more PICCs. It initiates P1CC communication activity by issuing a REQB/WUPB command to prompt for PICCs to respond.
During the anticollision sequence, it may happen that two or more PICCs respond simultaneously: this is a collision. The command set allows the PCD to handle sequences to separate P1CC transmissions in time. The PCD may repeat its anticollision procedure until it finds all PICCs in the operating volume.ISO IEC 14443-3 pdf download.