SLOA227B October 2015 – March 2019 TRF7964A , TRF7964A , TRF7970A , TRF7970A
The frame format for ISO14443A packets at 106 kbps during anticollision(shown in Figure 8) is based on NFC-A technology specifications in NFCForum-TS-DigitalProtocol-1.0 and the ISO 14443-3 Specifications. The Type A frame format does not include CRC bytes when sending anticollision commands, but does include the CRC bytes when sending tag selection and data exchange command.
When the initial RF collision is completed and no RF field has been detected (as shown in Figure 7) the following registers must be modified before and after the anticollision is completed (see Figure 9). For more information, see Section 3.
In the context of Type A, anticollision refers to the mandatory process for the retrieval of the UID, and does not imply support for detecting multiple Type A tags presented at the same time.
The ISO control register must be modified for the anticollision state to receive without CRC for the required commands (see the ISO14443-3 specification for more information). When the anticollision is completed, the ISO Control register must be modified to receive with CRC. Step 2 must be used to send commands to the passive target.