SNLA246C October   2015  – April 2024 DP83867CR , DP83867CS , DP83867E , DP83867IR , DP83867IS

 

  1.   1
  2.   Trademarks
  3. 1Introduction
  4. 2Troubleshooting the Application
    1. 2.1 Read and Check Register Values for Basic Health Check
    2. 2.2 Schematic and Layout Checklist
    3. 2.3 Component Checklist
      1. 2.3.1 Magnetics
      2. 2.3.2 Crystal / Oscillator
    4. 2.4 Peripheral Pin Checks
      1. 2.4.1 Power Supplies
      2. 2.4.2 RBIAS Voltage and Resistance
      3. 2.4.3 Probe the XI Clock
      4. 2.4.4 Probe the RESET_N Signal
      5. 2.4.5 Probe the Strap Pins During Initialization
      6. 2.4.6 Probe the Serial Management Interface Signals (MDC, MDIO)
      7. 2.4.7 Probe the MDI Signals
    5. 2.5 Link Quality Check
    6. 2.6 Built-in Self Test With Various Loopback Modes
    7. 2.7 Debugging MAC Interface
      1. 2.7.1 RGMII Debug
      2. 2.7.2 SGMII Debug
  5. 3Application Specific Debugs
    1. 3.1 Improving Link-up Margins for Short Cables
    2. 3.2 Improving Link Margins across Different Channels
    3. 3.3 Link up in 100Mbps Full Duplex Force Mode
    4. 3.4 Unstable Link Up Debug in 1Gbps communication
    5. 3.5 DP83867PHY and DP83867PHY Cannot Link Up in 1Gbps
    6. 3.6 Compliance Debug
    7. 3.7 EMC Debug
    8. 3.8 Tools and References
      1. 3.8.1 DP83867 Register Access
      2. 3.8.2 Extended Register Access
  6. 4Conclusion
  7. 5References
  8. 6Revision History

2.4.7 Probe the MDI Signals

When Auto-negotiation enable, A link pulse should be visible on the channel A transmit and receive differential pairs (TD_P_A and TD_M_A).

A short Ethernet cable with 100 Ohm terminations can be used for measuring the MDI signals. A terminated cable is shown in Figure 2-6. A connection diagram for making measurements with the terminated cable is shown in Figure 2-7.

GUID-5E846689-66F8-48BE-8C72-8853251E70F5-low.gifFigure 2-6 100 Ohm Terminated Cable for MDI Signal Measurement
GUID-58CE164C-71FC-42DC-8F49-3F12541C2654-low.gifFigure 2-7 Connection Diagram for 100M Terminated Cable

Auto-Negotation link pulses are nominally 100ns wide. Pulses are spaced by 62µs or 125µs and are transmitted in bursts. The bursts are nominally 2ms in duration and occur every 16ms. An example link pulse is shown below in Figure 2-8.

GUID-22BD880A-9BB6-472E-9D43-9BE77F83FD04-low.gifFigure 2-8 DP83867 Link Pulse

Observing this pulse confirms the PHY is on and attempting to link.