SLOS743M August   2011  – March 2020

PRODUCTION DATA.  

  1. 1Device Overview
    1. 1.1 Features
    2. 1.2 Applications
    3. 1.3 Description
    4. 1.4 Functional Block Diagram
  2. 2Revision History
  3. 3Device Characteristics
    1. 3.1 Related Products
  4. 4Terminal Configuration and Functions
    1. 4.1 Pin Diagram
    2. 4.2 Signal Descriptions
      1. Table 4-1 Terminal Functions
  5. 5Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Electrical Characteristics
    5. 5.5 Thermal Resistance Characteristics
    6. 5.6 Switching Characteristics
  6. 6Detailed Description
    1. 6.1  Overview
      1. 6.1.1 RFID and NFC Operation – Reader and Writer
      2. 6.1.2 NFC Device Operation – Initiator
      3. 6.1.3 NFC Device Operation – Target
        1. 6.1.3.1 Active Target
        2. 6.1.3.2 Passive Target
        3. 6.1.3.3 Card Emulation
    2. 6.2  System Block Diagram
    3. 6.3  Power Supplies
      1. 6.3.1 Supply Arrangements
      2. 6.3.2 Supply Regulator Settings
      3. 6.3.3 Power Modes
    4. 6.4  Receiver – Analog Section
      1. 6.4.1 Main and Auxiliary Receivers
      2. 6.4.2 Receiver Gain and Filter Stages
    5. 6.5  Receiver – Digital Section
      1. 6.5.1 Received Signal Strength Indicator (RSSI)
        1. 6.5.1.1 Internal RSSI – Main and Auxiliary Receivers
        2. 6.5.1.2 External RSSI
    6. 6.6  Oscillator Section
    7. 6.7  Transmitter – Analog Section
    8. 6.8  Transmitter – Digital Section
    9. 6.9  Transmitter – External Power Amplifier and Subcarrier Detector
    10. 6.10 TRF7970A IC Communication Interface
      1. 6.10.1 General Introduction
        1. 6.10.1.1 Continuous Address Mode
        2. 6.10.1.2 Noncontinuous Address Mode (Single Address Mode)
        3. 6.10.1.3 Direct Command Mode
        4. 6.10.1.4 FIFO Operation
      2. 6.10.2 Parallel Interface Mode
      3. 6.10.3 Reception of Air Interface Data
      4. 6.10.4 Data Transmission From MCU to TRF7970A
      5. 6.10.5 Serial Interface Communication (SPI)
        1. 6.10.5.1 Serial Interface Mode With Slave Select (SS)
      6. 6.10.6 Direct Mode
    11. 6.11 TRF7970A Initialization
    12. 6.12 Special Direct Mode for Improved MIFARE Compatibility
    13. 6.13 NFC Modes
      1. 6.13.1 Target
      2. 6.13.2 Initiator
    14. 6.14 Direct Commands from MCU to Reader
      1. 6.14.1 Command Codes
        1. 6.14.1.1  Idle (0x00)
        2. 6.14.1.2  Software Initialization (0x03)
        3. 6.14.1.3  Initial RF Collision Avoidance (0x04)
        4. 6.14.1.4  Response RF Collision Avoidance (0x05)
        5. 6.14.1.5  Response RF Collision Avoidance (0x06, n = 0)
        6. 6.14.1.6  Reset FIFO (0x0F)
        7. 6.14.1.7  Transmission With CRC (0x11)
        8. 6.14.1.8  Transmission Without CRC (0x10)
        9. 6.14.1.9  Delayed Transmission With CRC (0x13)
        10. 6.14.1.10 Delayed Transmission Without CRC (0x12)
        11. 6.14.1.11 Transmit Next Time Slot (0x14)
        12. 6.14.1.12 Block Receiver (0x16)
        13. 6.14.1.13 Enable Receiver (0x17)
        14. 6.14.1.14 Test Internal RF (RSSI at RX Input With TX ON) (0x18)
        15. 6.14.1.15 Test External RF (RSSI at RX Input with TX OFF) (0x19)
    15. 6.15 Register Description
      1. 6.15.1 Register Preset
      2. 6.15.2 Register Overview
      3. 6.15.3 Detailed Register Description
        1. 6.15.3.1 Main Configuration Registers
          1. 6.15.3.1.1 Chip Status Control Register (0x00)
          2. 6.15.3.1.2 ISO Control Register (0x01)
        2. 6.15.3.2 Control Registers – Sublevel Configuration Registers
          1. 6.15.3.2.1  ISO/IEC 14443 TX Options Register (0x02)
          2. 6.15.3.2.2  ISO/IEC 14443 High-Bit-Rate and Parity Options Register (0x03)
          3. 6.15.3.2.3  TX Timer High Byte Control Register (0x04)
          4. 6.15.3.2.4  TX Timer Low Byte Control Register (0x05)
          5. 6.15.3.2.5  TX Pulse Length Control Register (0x06)
          6. 6.15.3.2.6  RX No Response Wait Time Register (0x07)
          7. 6.15.3.2.7  RX Wait Time Register (0x08)
          8. 6.15.3.2.8  Modulator and SYS_CLK Control Register (0x09)
          9. 6.15.3.2.9  RX Special Setting Register (0x0A)
          10. 6.15.3.2.10 Regulator and I/O Control Register (0x0B)
        3. 6.15.3.3 Status Registers
          1. 6.15.3.3.1  IRQ Status Register (0x0C)
          2. 6.15.3.3.2  Interrupt Mask Register (0x0D) and Collision Position Register (0x0E)
          3. 6.15.3.3.3  RSSI Levels and Oscillator Status Register (0x0F)
          4. 6.15.3.3.4  Special Functions Register (0x10)
          5. 6.15.3.3.5  Special Functions Register (0x11)
          6. 6.15.3.3.6  Adjustable FIFO IRQ Levels Register (0x14)
          7. 6.15.3.3.7  NFC Low Field Level Register (0x16)
          8. 6.15.3.3.8  NFCID1 Number Register (0x17)
          9. 6.15.3.3.9  NFC Target Detection Level Register (0x18)
          10. 6.15.3.3.10 NFC Target Protocol Register (0x19)
        4. 6.15.3.4 Test Registers
          1. 6.15.3.4.1 Test Register (0x1A)
          2. 6.15.3.4.2 Test Register (0x1B)
        5. 6.15.3.5 FIFO Control Registers
          1. 6.15.3.5.1 FIFO Status Register (0x1C)
          2. 6.15.3.5.2 TX Length Byte1 Register (0x1D), TX Length Byte2 Register (0x1E)
  7. 7Applications, Implementation, and Layout
    1. 7.1 TRF7970A Reader System Using SPI With SS Mode
      1. 7.1.1 General Application Considerations
      2. 7.1.2 Schematic
    2. 7.2 Layout Considerations
    3. 7.3 Impedance Matching TX_Out (Pin 5) to 50 Ω
    4. 7.4 Reader Antenna Design Guidelines
  8. 8Device and Documentation Support
    1. 8.1 Getting Started and Next Steps
    2. 8.2 Device Nomenclature
    3. 8.3 Tools and Software
    4. 8.4 Documentation Support
    5. 8.5 Support Resources
    6. 8.6 Trademarks
    7. 8.7 Electrostatic Discharge Caution
    8. 8.8 Glossary
  9. 9Mechanical, Packaging, and Orderable Information

6.10.1 General Introduction

The communication interface to the reader can be configured in two ways: with a eight line parallel interface (D0:D7) plus DATA_CLK, or with a 4-wire Serial Peripheral Interface (SPI). The SPI interface uses traditional Master Out/Slave In (MOSI), Master In/Slave Out (MISO), Slave Select, and DATA_CLK lines.

These communication modes are mutually exclusive; that is, only one mode can be used at a time in the application.

When the SPI interface is selected, the unused I/O_2, I/O_1, and I/O_0 pins must be hard-wired as shown in Table 6-10. At power up, the TRF7970A samples the status of these three pins and then enters one of the possible SPI modes.

The TRF7970A always behaves as the slave device, and the microcontroller (MCU) behaves as the master device. The MCU initiates all communications with the TRF7970A, and the TRF7970A makes use of the Interrupt Request (IRQ) pin in both parallel and SPI modes to prompt the MCU for servicing attention.

Table 6-10 Pin Assignment in Parallel and Serial Interface Connection or Direct Mode

PIN PARALLEL PARALLEL (DIRECT MODE) SPI WITH SS SPI WITHOUT SS(5)
DATA_ CLK DATA_CLK DATA_CLK DATA_CLK from master DATA_CLK from master
I/O_7 A/D[7] Not used MOSI(1) = data in (reader in) MOSI(1) = data in (reader in)
I/O_6 A/D[6] Direct mode, data out (subcarrier or bit stream) MISO(2) = data out (MCU out) MISO(2) = data out (MCU out)
I/O_5(3) A/D[5] Direct mode, strobe – bit clock out See (3). See (3).
I/O_4 A/D[4] Not used SS – slave select(4) Not used
I/O_3 A/D[3] Not used Not used Not used
I/O_2 A/D[2] Not used At VDD At VDD
I/O_1 A/D[1] Not used At VDD At VSS
I/O_0 A/D[0] Not used At VSS At VSS
IRQ IRQ interrupt IRQ interrupt IRQ interrupt IRQ interrupt
(1) MOSI = master out, slave in
(2) MISO = master in, slave out
(3) I/O_5 pin is used only for information when data is put out of the chip (for example, reading 1 byte from the chip). It is necessary first to write in the address of the register (8 clocks) and then to generate another 8 clocks for reading out the data. The I/O_5 pin goes high during the second 8 clocks. But for normal SPI operations, I/O_5 pin is not used.
(4) Slave select pin is active low
(5) FIFO is not accessible in SPI without SS mode. See the TRF7970A Silicon Errata for detailed information.

Communication is initialized by a start condition, which is expected to be followed by an Address/Command word (Adr/Cmd). The Adr/Cmd word is 8 bits long, and Table 6-11 shows its format.

Table 6-11 Address and Command Word Bit Distribution

BIT DESCRIPTION BIT FUNCTION ADDRESS COMMAND
B7 Command control bit 0 = Address
1 = Command		 0 1
B6 Read/Write 0 = Write
1 = Read		 R/W 0
B5 Continuous address mode 1 = Continuous mode R/W 0
B4 Address/Command bit 4 Adr 4 Cmd 4
B3 Address/Command bit 3 Adr 3 Cmd 3
B2 Address/Command bit 2 Adr 2 Cmd 2
B1 Address/Command bit 1 Adr 1 Cmd 1
B0 Address/Command bit 0 Adr 0 Cmd 0

The MSB (bit 7) determines if the word is to be used as a command or as an address. The last two columns of Table 6-11 show the function of the separate bits if either address or command is written. Data is expected once the address word is sent. In continuous-address mode (Cont. mode = 1), the first data that follows the address is written (or read) to (from) the given address. For each additional data, the address is incremented by one. Continuous mode can be used to write to a block of control registers in a single stream without changing the address; for example, setup of the predefined standard control registers from the MCU nonvolatile memory to the reader. In noncontinuous address mode (simple addressed mode), only one data word is expected after the address.

Address Mode is used to write or read the configuration registers or the FIFO. When writing more than 12 bytes to the FIFO, the Continuous Address Mode should be set to 1.

Command Mode is used to enter a command resulting in reader action (for example, initialize transmission, enable reader, and turn reader on or off).

The following sections give examples of the expected communications between an MCU and the TRF7970A.