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

5.1 SQI Application Startup

While TDR can provide information about the existence and location of cable faults, a real time monitor of the link quality can provide valuable information before a fault occurs. The DP83TD510E provides real time signal-to-noise ratio monitoring.

The cable quality, connector contact, and surrounding environment contribute to the overall channel quality. The Signal Quality Indicator (SQI) can provide insight into the physical connections in an application assembly before it ships, the link quality of a system in noisy environments and immunity testing, or the lifetime trend a of product’s health as it ages.

The DP83TD510E monitors link quality by measuring the SNR at periodic intervals whenever an active link is established. The PHY measures the accumulated mean-square error (MSE) in the received signal at the PAM3 slicer from its sliced output level. The signal quality monitoring functions are run automatically in the background of the PHY; there is no need to enable this feature through register settings.

The MSE stored as a hexadecimal value in the SQI register [0x0A85] can be converted to dB by dividing by 217 and calculating MSE (dB) = 10 * log10 MSE

  1. Convert bits [14:0] to decimal form for MSE (decimal)
  2. MSE (dB) = 10 * log10 (MSE/217)
  3. SNR(dB) = -10 * log10 (MSE/217) - 1.76 dB