1 Introduction

The TRF7970A supports three operational modes: reader/writer, card emulation, and peer-to-peer. This document describes on how to use the TRF7970A in card emulation mode. Card emulation allows an NFC enabled system to act as or 'emulate' a tag platform. In the case of the TRF7970A, it is possible to emulate both Type 4A and Type 4B tags concurrently. This feature is a differentiator when compared to static tags that typically offer a single tag type platform.

Card emulation for Type 4A uses ISO/IEC 14443A technology at a baud rate of 106 kbps. Card emulation for Type 4B uses ISO/IEC 14443B technology at a baud rate of 106 kbps. After technology selection for either mode has been completed, the higher layers are the same (as shown in Figure 1).

When configured for the aforementioned mode, the TRF7970A transceiver behaves as an emulated card, so it does not produce its own RF field. When a RF field is presented from a reader, and properly formatted commands are issued, the transceiver load modulates the reader's field to communicate with it.

Figure 1. Card Emulation Layers Including the PHY (TRF7970A)

A 16-bit and a 32-bit microcontroller are used to interface with the TRF7970A to demonstrate a reference example of the card emulation mode. The firmware supports flexible functions that allow the user to enable or disable the supported card emulation modes. Additionally, the firmware demonstrates how to format various NDEF message types for card emulation applications, and allows NFC-enabled smart phones to write custom NDEF content to the device.

Table 1 lists the NFC-enabled devices that were used to validate the firmware.