SNLA443A December   2023  – August 2025 DP83869HM

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1DP83869 Application Overview
  5. 2Troubleshooting the Application
    1. 2.1 Schematic and Layout Checklist
    2. 2.2 Device Health Checks
      1. 2.2.1 Voltage Checks
      2. 2.2.2 Probe the RESET_N Signal
      3. 2.2.3 Probe RBIAS
      4. 2.2.4 Probe the XI Clock
      5. 2.2.5 Probe the Strap Pins During Initialization
        1. 2.2.5.1 Configuring Correct Operational Mode
      6. 2.2.6 Probe the Serial Management Interface (MDC, MDIO)
        1. 2.2.6.1 Read and Check Register Values
    3. 2.3 MDI Health Checks
      1. 2.3.1 Magnetics
      2. 2.3.2 Probe the MDI Signals
      3. 2.3.3 Check the Link Quality
        1. 2.3.3.1 Improving Short Cable Link Margin
        2. 2.3.3.2 Improving Inter-channel Link Margin
      4. 2.3.4 Compliance
    4. 2.4 MII Health Checks
      1. 2.4.1 MII Check
      2. 2.4.2 RGMII Check
      3. 2.4.3 SGMII Check
    5. 2.5 Loopback and PRBS
      1. 2.5.1 Loopback Modes
      2. 2.5.2 Transmitting and Receiving Packets with the MAC
      3. 2.5.3 Transmitting and Receiving Packets with BIST
  6. 3Operational Mode Clarification
    1. 3.1 Bridge Modes
    2. 3.2 Fiber Configuration
      1. 3.2.1 Fiber Registers
      2. 3.2.2 Media Converter LED Behavior
  7. 4Tools and References
    1. 4.1 Extended Register Access
      1. 4.1.1 Read (No Post Increment) Operation
      2. 4.1.2 Write (No Post Increment) Operation
    2. 4.2 Software and Driver Debug on Linux
      1. 4.2.1 Common Terminal Outputs
  8. 5Summary
  9. 6References
  10. 7Revision History

3.2 Fiber Configuration

DP83869HM is capable of 100Base-FX and 1000Base-X fiber communication. When using fiber, speed is not determined by auto-negotiation. Both sides of the link must be configured to the same operating speed. The pins used for fiber are the same pins used for SGMII: SIP/SIN and SOP/SON. The DP83869HM must be set to either SGMII to Copper, RGMII/MII to fiber, or Copper to fiber. A SGMII to fiber connection is not possible. For more information on debugging a fiber interface, please see our Ethernet PHY Fiber Debug Guide.