SBAS940 December   2018 DAC8742H

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Timing Requirements
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  HART Modulator
      2. 7.3.2  HART Demodulator
      3. 7.3.3  FOUNDATION FIELDBUS / PROFIBUS PA Manchester Encoder
      4. 7.3.4  FOUNDATION FIELDBUS / PROFIBUS PA Manchester Decoder
      5. 7.3.5  Internal Reference
      6. 7.3.6  Clock Configuration
      7. 7.3.7  Reset and Power-Down
      8. 7.3.8  Full-Duplex Mode
      9. 7.3.9  I/O Selection
      10. 7.3.10 Jabber Inhibitor
    4. 7.4 Device Functional Modes
      1. 7.4.1 UART Interfaced HART
      2. 7.4.2 UART Interfaced FOUNDATION FIELDBUS / PROFIBUS PA
      3. 7.4.3 SPI Interfaced HART
      4. 7.4.4 SPI Interfaced FOUNDATION FIELDBUS / PROFIBUS PA
      5. 7.4.5 Interface
        1. 7.4.5.1 UART
          1. 7.4.5.1.1 UART Carrier Detect
        2. 7.4.5.2 SPI
          1. 7.4.5.2.1 SPI Cyclic Redundancy Check
          2. 7.4.5.2.2 SPI Interrupt Request
    5. 7.5 Register Maps
      1. 7.5.1 CONTROL Register (Offset = 2h) [reset = 0x8042]
        1. Table 4. CONTROL Register Field Descriptions
      2. 7.5.2 RESET Register (Offset = 7h) [reset = 0x0000]
        1. Table 5. RESET Register Field Descriptions
      3. 7.5.3 MODEM_STATUS Register (Offset = 20h) [reset = 0x0000]
        1. Table 6. MODEM_STATUS Register Field Descriptions
      4. 7.5.4 MODEM_IRQ_MASK Register (Offset = 21h) [reset = 0x0024]
        1. Table 7. MODEM_IRQ_MASK Register Field Descriptions
      5. 7.5.5 MODEM_CONTROL Register (Offset = 22h) [reset = 0x0048]
        1. Table 8. MODEM_CONTROL Register Field Descriptions
      6. 7.5.6 FIFO_D2M Register (Offset = 23h) [reset = 0x0200]
        1. Table 9. FIFO_D2M Register Field Descriptions
      7. 7.5.7 FIFO_M2D Register (Offset = 24h) [reset = 0x0200]
        1. Table 10. FIFO_M2D Register Field Descriptions
      8. 7.5.8 FIFO_LEVEL_SET Register (Offset = 25h) [reset = 0x0000]
        1. Table 11. FIFO_LEVEL_SET Register Field Descriptions
      9. 7.5.9 PAFF_JABBER Register (Offset = 27h) [reset = 0x0000]
        1. Table 12. PAFF_JABBER Register Field Descriptions
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Design Recommendations
      2. 8.1.2 Selecting the Crystal/Resonator
      3. 8.1.3 Included Functions and Filter Selection
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 DAC8742H HART Modem
        2. 8.2.2.2 2-Wire Current Loop
        3. 8.2.2.3 Regulator
        4. 8.2.2.4 DAC
        5. 8.2.2.5 Amplifiers
        6. 8.2.2.6 Diodes
        7. 8.2.2.7 Passives
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

7.5.5 MODEM_CONTROL Register (Offset = 22h) [reset = 0x0048]

This register controls various modem features including: FF/PA Manchester data polarity, number of FF/PA preamble bits, analog output amplitude, modem enable, duplex mode, and request to send.

MODEM_CONTROL is shown in Figure 27 and described in Table 8.

Return to Summary Table.

Figure 27. MODEM_CONTROL Register
15 14 13 12 11 10 9 8
FFPA_POL FFPA_PREAMBLE RESERVED TX_AMP
R/W R/W R R/W
7 6 5 4 3 2 1 0
TX_AMP MOD_EN DUP_EN RESERVED RTS
R/W R/W R/W R R/W

Table 8. MODEM_CONTROL Register Field Descriptions

Bit Field Type Reset Description
15 FFPA_POL R/W 0 Sets the transmitted polarity of the Manchester encoded data
0 = Logical 1 is transmitted as a transition from high-to-low (default)
1 = Logical 1 is transmitted as a transition from low-to-high
14-12 FFPA_PREAMBLE R/W 0 Number of preamble bytes sent is the value programmed in this register plus 1
11-9 RESERVED R 0 Reserved
8-4 TX_AMP R/W 00100 Unsigned binary value that controls the amplitude (HART mode only) of the transmitted waveform in 25mVpp steps. Default value 00100 for 500mVpp output amplitude. Amplitude may vary from 400mVpp to 800mVpp.
3 MOD_EN R/W 1 0 = Disables TX/RX of the modem
1 = Enables TX/RX of the modem (default)
2 DUP_EN R/W 0 0 – TX FIFO is not connected to RX FIFO (default)
1 = Connects TX FIFO to RX FIFO
1 RESERVED R 0 Reserved
0 RTS R/W 0 0 = No active request to send in HART mode (default)
1 = Active request to send in HART mode