SLOA192B April 2014 – March 2019 TRF7970A , TRF7970A
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NFC active and passive peer-to-peer communication using the TRF7970A
- Trademarks
- 1 Introduction
- 2 Initial RF Collision
- 3 TRF7970A Register Settings
- 4 Peer-to-Peer at 106 kbps
- 5 Peer-to-Peer at 212 kbps and 424 kbps
- 6 Hardware Description
- 7 Passive and Active Peer-to-Peer Firmware Example
- 8 Quick Start Guide
- 9 Operational Overview
- 10 Peer-to-Peer Interoperability Results
- 11 Conclusion
- 12 References
- Revision History
4.2.2 Target
Initially the TRF7970A must be receiving without CRC. After receiving commands from the initiator, the following registers must be modified before and after the anticollision is completed:
- ISO Control register (0x01) → 0xA4 (ISO14443A 106 kbps, receive without CRC during anticollision, before Select command)
or
ISO Control register (0x01) → 0x24 (ISO14443A 106 kbps, receive with CRC, after anticollision is completed). - 2. Send packet:
- Reset FIFO (0x0F) direct command.
- Transmission without (0x10, anticollision before Select command) or with (0x11, after anticollision is completed) CRC direct command.
- c. TX Length Byte 1 and 2 (0x1D and 0x1E) registers.
- Write the command to the FIFO.
The ISO control register needs to be modified for the anticollision state to receive without CRC for the required commands. For more information, see the ISO14443-3 specification. Once the anticollision is completed the ISO Control register needs to be modified to receive with CRC. Step 2 must be used to send commands to the initiator.
Figure 9. Peer-to-Peer 106-kbps Initiator Anticollision for Passive Communication