SNLU324 March   2023

 

  1.   Abstract
  2.   Trademarks
  3. 1Hardware Description and Setup
    1. 1.1 Required Hardware
    2. 1.2 General Hardware Test Setup Procedure
    3. 1.3 Hardware Configuration to Use External 25 MHz Oscillator for CAL_CLK_IN
  4. 2Software Description
    1. 2.1 Software Installation Sequence
    2. 2.2 Latte Functional Overview
    3. 2.3 Useful Latte Short-Cuts
    4. 2.4 DS560DF410EVM Initialization Through the Latte GUI
      1. 2.4.1 Connect Latte to Board
      2. 2.4.2 Compile Libraries
      3. 2.4.3 Example: Programming DS560DF410EVM for 26.5625 GBd PAM4 Test Case
      4. 2.4.4 Retimer Configuration
      5. 2.4.5 Retimer Useful Functions (Contained in the usefulFunctions.py Latte Script)
      6. 2.4.6 Vertical Eye Monitor
  5. 3Related Documentation
    1. 3.1 Supplemental Content
  6. 4EVM Cable Assemblies

2.4.5 Retimer Useful Functions (Contained in the usefulFunctions.py Latte Script)

  • Readback channel init status/lock status: The CDR lock status for the selected channel can be read using the following function.
  • Get tempsense result: The user may perform a coarse reading of the retimer internal temperature.
  • Readback channel init info: Channel initialization info such as CTLE settings and bring-up stage status can be read using the following function.
  • Readback FOM: The internal figure of merit used by the retimer to guide the EQ auto adaptation process can be read by the user.
  • Readback BER: The internal BER checker for the retimer channel currently selected can be used when the length of the PRBS data is known a priori. The prbsBERCheck function prints the BER and the total number of bits over which it is computed.
    Note: Observing Total bits = 1 on the log window means PRBS sync is not achieved. Change the input data to one of the supported PRBS patterns.
  • Readback RX coefficients: Can be used to read the weights of several FFE and DFE EQ taps.
  • Check RX input level: After the channel initialization process has been completed, the signalDetect function can be used to check presence of signal at the Rx input of the selected retimer channel.

  • Configure Transmitter: The transmit data can be configured by mode and pattern variables.

    • mode = 0: Transmits re-timed data irrespective of the pattern variable.
    • mode = 1: Transmits clock pattern, frequency of which is determined by the pattern variable.
    • mode = 2: Set transmitter to PRBS pattern generator.
    • pattern: Select the desired pattern by entering the numeric value. Table 2-1 provides more information.
Table 2-1 PRBS Pattern Codes
Pattern:PRBS:
07
19
315
423
531
813

PRBSQ pattern can be enabled by setting prbsQEn = 1. To configure transmitter to send PRBS13Q pattern, set mode = 2, pattern = 8 and prbsQEn = 1. The PRBSQ pattern is only applicable to PAM4.

  • Swing and the pre or post emphasis setting of the transmitter can be controlled by the function ds560.setTxParams.
    • swing:
      • 0 -> 1 V
      • 1 -> 880 mV
      • 3 -> 760 mV
    • pre2: value of 0 to 7 correspond to 0 to 15%.
    • pre: value of 0 to 15 correspond to 0 to 31.25%.
    • post: value of 0 to 15 correspond to 0 to 31.25%.