SNLA364C March   2021  – June 2022 DP83TD510E

 

  1.   Abstract
  2.   Trademarks
  3. 1 Introduction
  4. 2 1-V and 2.4-V p2p Mode Scripts
  5. 3 Time-Domain Reflectometry
    1. 3.1 TDR Application Startup
      1. 3.1.1 TDR_CFG (Address = 0x001E) [Reset = 0x0000]
      2. 3.1.2 TDR_Fault_Status (Address = 0x030C) [Reset = 0x0000]
    2. 3.2 TDR Test Procedure
  6. 4 Active Link Cable Diagnostics
    1. 4.1 ALCD Application Startup
    2. 4.2 ALCD Test Procedure
      1. 4.2.1 Cable Calibration
      2. 4.2.2 Cable Quality Measurement
  7. 5 Signal Quality Indicator
    1. 5.1 SQI Application Startup
      1. 5.1.1 MSE Detection (Address = 0x0A85 ) [Reset = 0x0000]
    2. 5.2 SQI Test Procedure
  8. 6 Cable Diagnostics Summary
  9. 7 Loopback Modes
    1. 7.1 BISCR (Address = 0x0016) [Reset = 0x0100]
  10. 8 Pseudo-Random Bit Sequence Functions
    1. 8.1 PRBS_CFG_1 (Address = 0x0119) [Reset = 0x0574]
    2. 8.2 PRBS_STATUS_4 (Address = 0x011F) [Reset = 0x0000]
  11. 9 USB to MDIO Procedure
  12. 10IEEE 802.3cg PMA Compliance
  13. 11Revision History

4.1 ALCD Application Startup

While TDR offers a way to measure cable length of a system without an established link, Active Link Cable Diagnostic (ALCD) allows the PHY to determine the cable length during an active link with its link partner. The PHY uses passive digital signal processing along with pre-defined cable parameters to achieve the highest accuracy in its cable length estimate. The estimated cable length can be cross verified with the physical length of the cable to determine whether there is deviation in cable characteristics and understand how the PHY may perform as the cable ages.

It is important to note that in single-pair Ethernet applications, cable selection varies more widely than in standard Ethernet applications (where CAT5, CAT5e, CAT6 cables are dominantly used). As such, the ALCD feature in the DP83TD510E allows designers to tailor their cable diagnostic tool to the specific cable in their application to generate the most accurate cable length estimate.

The ALCD usage is divided into two steps:
  1. Calibration of the cable characteristics
  2. Measurement of the cable quality