SNLA423 March   2023 DP83826E

 

  1. 1Trademarks
  2. 2DP83826 Application Overview
  3. 3Troubleshooting the Application
    1. 3.1 Read and Check Register Values
    2. 3.2 Schematic and Layout Checklist
    3. 3.3 Component Checklist
    4. 3.4 Peripheral Pin Checks
      1. 3.4.1 Power Supplies
      2. 3.4.2 Probe the XI Clock
      3. 3.4.3 Probe the RESET_N Signal
      4. 3.4.4 Probe the Strap Pins During Initialization
      5. 3.4.5 Probe the Serial Management Interface Signals (MDC, MDIO)
      6. 3.4.6 Probe the MDI Signals
    5. 3.5 Link Quality Check
    6. 3.6 Built-In Self Test with Various Loopback Modes
    7. 3.7 Debugging MAC Interface
    8. 3.8 Tools and References
      1. 3.8.1 DP83826 Register Access
      2. 3.8.2 Extended Register Access
      3. 3.8.3 Application Note References
  4. 4Conclusion
  5. 5Revision History

3.4.6 Probe the MDI Signals

In the default configuration, Auto-negotiation and Auto-MDIX will be enabled. A link pulse should be visible on the channel transmit and receive differential pair (TD_P, TD_M).

A short Ethernet cable with 100 Ohm terminations can be used for measuring the MDI signals. A terminated cable is shown in Figure 3-2. A connection diagram for making measurements with the terminated cable is shown in Figure 3-3.

GUID-50F93AF4-1E27-4B57-83A0-2C3DF68F2B65-low.gifFigure 3-2 100 Ω Terminated Cable for MDI Signal Measurement
GUID-74588587-DC9F-4F35-B7FC-E94AD26D2D41-low.gifFigure 3-3 Connection Diagram for 100 M Terminated Cable

Auto-Negotation link pulses are nominally 100ns wide. Pulses are spaced by 62 µs or 125 µs and are transmitted in bursts. The bursts are nominally 2 ms in duration and occur every 16 ms. Figure 3-4shows a link pulse.

GUID-F36104C6-D7E6-40F5-A124-A4418C320C0F-low.gifFigure 3-4 DP83826 Link Pulse