SNLA443 December   2023 DP83869HM

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1DP83869 Application Overview
  5. 2Troubleshooting the Application
    1. 2.1 Configuring Correct Operational Mode
    2. 2.2 Schematic and Layout Checklist
    3. 2.3 Component Checklist
    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 Built-In Self Test with Various Loopback Modes
    6. 2.6 Debugging MAC Interface
      1. 2.6.1 RGMII
      2. 2.6.2 SGMII
  6. 3Operational Mode Clarification
    1. 3.1 Bridge Modes
    2. 3.2 Fiber Configuration
      1. 3.2.1 Fiber Registers
  7. 4Tools and References
    1. 4.1 DP83869HM Register Access
    2. 4.2 Extended Register Access
      1. 4.2.1 Read (No Post Increment) Operation
      2. 4.2.2 Write (No Post Increment) Operation
    3. 4.3 Software and Driver Debug on Linux
      1. 4.3.1 Common Terminal Outputs
  8. 5Summary
  9. 6References

2.5 Built-In Self Test with Various Loopback Modes

There are several options for loopback that test and verify various functional blocks within the PHY. Enabling loopback mode allows in-circuit testing of the digital and analog data paths. Generally, the DP83869HM can be configured to one of the near-end loopback modes or to the far-end (reverse) loopback. The Loopback Mode section in the data sheet provides additional details on loopbacks and how to configure them.

The availability of Loopback depends on the operational mode of the PHY. The Link Status in these loopback modes is also effected by the operational mode. Table 2-5 lists out the exceptions where Loopbacks are not available.

GUID-C4030C84-3472-45F8-AA28-940E52FB9CE4-low.gif Figure 2-9 Loopbacks
Table 2-5 Loopback Availability Exception
OP MODE LOOPBACK EXCEPTION
Copper PCS 10M
Fiber MII 100M
PCS 100M
Analog 100M, 1000M
SGMII to RGMII PCS 10M, 100M, 1000M
Digital 10M, 100M, 1000M
Analog 10M, 100M, 1000M
External 10M, 100M, 1000M
RGMII to SGMII PCS 10M, 100M, 1000M
External 10M, 100M, 1000M
Media Convertor MII 100M, 1000M
Analog 100M on Fiber Interface
External 100M on Fiber Interface
100M, 1000M on Copper Interface