SLOA192B April   2014  – March 2019 TRF7970A , TRF7970A

 

  1.   NFC active and passive peer-to-peer communication using the TRF7970A
    1.     Trademarks
    2. 1  Introduction
    3. 2  Initial RF Collision
    4. 3  TRF7970A Register Settings
    5. 4  Peer-to-Peer at 106 kbps
      1. 4.1 Active Communication
        1. 4.1.1 Initiator
        2. 4.1.2 Target
      2. 4.2 Passive Communication
        1. 4.2.1 Initiator
        2. 4.2.2 Target
    6. 5  Peer-to-Peer at 212 kbps and 424 kbps
      1. 5.1 Active Communication
        1. 5.1.1 Initiator
        2. 5.1.2 Target
      2. 5.2 Passive Communication
        1. 5.2.1 Initiator
        2. 5.2.2 Target
    7. 6  Hardware Description
      1. 6.1 LaunchPad™ Development Kit and BoosterPack™ Plug-in Module Setup
        1. 6.1.1 BoosterPack Plug-in Module: DLP-7970ABP
        2. 6.1.2 LaunchPad Development Kit: MSP-EXP430F5529LP
        3. 6.1.3 LaunchPad Development Kit: MSP-EXP432P401R
      2. 6.2 Bundle Available for Purchase
    8. 7  Passive and Active Peer-to-Peer Firmware Example
      1. 7.1 Peer-to-Peer APIs
      2. 7.2 Implementing a Peer-to-Peer Sample Application
        1. 7.2.1 Low-Level Initialization
        2. 7.2.2 Peer-to-Peer NFC Stack Setup
        3. 7.2.3 Sending NDEF Packets
        4. 7.2.4 Receiving NDEF Packets
    9. 8  Quick Start Guide
    10. 9  Operational Overview
    11. 10 Peer-to-Peer Interoperability Results
    12. 11 Conclusion
    13. 12 References
  2.   Revision History

3 TRF7970A Register Settings

After powering up the TRF7970A, the MCU must send SOFT_INIT (0x03) and IDLE (0x00) direct commands to enable the passive target mode at 106 kbps. Table 2 shows the default value of registers 0x00 through 0x16 and 0x18 through 0x1C after the commands are issued. The table also shows the registers that must be modified for both target and initiator modes.

The ISO Control (0x01) register is modified whenever the peer-to-peer technology or bit rate changes. The Chip Status Control (0x00) register is modified after initialization and whenever the RF field is enabled or disabled. The Modulator and SYS_CLK Control (0x09), RX Special Settings (0x0A), and Regulator and I/O Control (0x0B) registers need to be modified only once, right after initialization. The NFC Low Field Detection Level (0x16) register needs to be modified only for Target mode operation. The NFC Target Detection Level (0x18) register must be modified after initialization for Target mode operation, and also for Initiator mode operation based on the TRF7970A silicon errata.

Table 2. TRF7970A Default Register Values After Receiving SOFT_INIT and IDLE Direct Commands

Address Register Value Notes Requires Modification
Initiator Target
0x00 Chip status control 0x01 5-V operation Yes Yes
0x01 ISO control 0x21 Passive target Yes Yes
0x02 ISO14443B TX options 0x00 Automatic single device detection (SDD) disabled No No
0x03 ISO14443A high bit-rate options 0x00 See TRF7970A data sheet No No
0x04 TX timer setting, H-byte 0xC1 See TRF7970A data sheet No No
0x05 TX timer setting, L-byte 0xC1 See TRF7970A data sheet No No
0x06 TX pulse-length control 0x00 See TRF7970A data sheet No No
0x07 RX no response wait 0x0E See TRF7970A data sheet No No
0x08 RX wait time 0x07 See TRF7970A data sheet No No
0x09 Modulator and SYS_CLK control 0x91 27-MHz crystal enabled, SYS_CLK enabled, OOK (100%) Yes Yes
0x0A RX special setting 0x10 Band-pass 100 kHz to 1.5 MHz Yes Yes
0x0B Regulator and I/O control 0x87 Automatic VDD RF Yes Yes
0x0C IRQ status 0x00 See TRF7970A data sheet No No
0x0D Collision position and interrupt mask 0x3E See TRF7970A data sheet No No
0x0E Collision position 0x00 See TRF7970A data sheet No No
0x0F RSSI levels and oscillator status 0x40 See TRF7970A data sheet No No
0x10 Special function 0x00 See TRF7970A data sheet No No
0x11 Special function 0x00 See TRF7970A data sheet No No
0x12 RAM 0x00 See TRF7970A data sheet No No
0x13 RAM 0x00 See TRF7970A data sheet No No
0x14 Adjustable FIFO IRQ levels 0x00 See TRF7970A data sheet Optional Optional
0x15 Reserved 0x00 N/A No No
0x16 NFC low field detection level 0x00 See TRF7970A data sheet No Yes
0x18 NFC target detection level 0x00 See TRF7970A data sheet Yes Yes
0x19 NFC target protocol 0x00 See TRF7970A data sheet No No
0x1A Test 0x00 See TRF7970A data sheet No No
0x1B Test 0x00 See TRF7970A data sheet No No
0x1C FIFO status 0x00 See TRF7970A data sheet No No