11 Conclusion

Peer-to-peer is one of three modes supported by the TRF7970A transceiver. The existing P2P NFC stack supports active and passive communication for both initiator and target at 106 kbps, 212 kbps, and 424 kbps. The transceiver that is initially polling and initiates the communication is the initiator. The transceiver that is initially listening is the target. The initiator always generates the RF field for both active and passive communication modes. However, the target generates its own RF field for active communication and load modulates the initiator's RF field for passive communication. To avoid two devices enabling their RF field at the same time, one must perform an initial RF collision (see Section 2) before enabling its own RF field.

The P2P demo has two modes: a stand-alone mode and a TI NFC Tool GUI mode. The stand-alone mode is the only way to test sending a large NDEF packet (3.6kB), however, using the TI NFC Tool GUI allows you to modify the default peer-to-peer modes enabled at power up. Furthermore, the GUI can be used to test for throughput rates when NDEF packets (larger than 1000 bytes) are sent from an NFC-enabled device to the TRF7970A transceiver.

Based on the tests executed with NFC-enabled devices in Table 1, the newer NFC-enabled devices interoperability with the TRF7970A is better. For legacy devices, the active communication may not be supported at all for either target or initiator at all bit rates. For newer devices, active communication has mixed results in terms of support, reliability and robust connections. Therefore, it is recommended to use passive communication over active communication.

As downloaded, the firmware example includes the full TI NFC stack which supports peer-to-peer, card emulation, and reader/writer modes. For applications that do not require all NFC operating modes, there are configuration options available to reduce the NFC stack memory footprint (only compiling required operating modes). These configurations can be made by modifying the #define statements within the nfc_config.h file, located at [Install Path]\nfclink\Source\headers.

For more information about NFC card emulation operation, see NFC card emulation using the TRF7970A.

For more information about NFC reader/writer, see NFC/HF RFID reader/writer using the TRF7970A.