SNLA437A December 2023 – October 2025 DP83822H , DP83822HF , DP83822I , DP83822IF , DP83826I
After establishing a valid link and confirming the key status register values and visually verifying that the link LED is lit, the link may still be seeing any packet errors.
There are several possible sources of link problems:
Link partner transmit problem
With the PHY powered and connected to a link partner, the following register can be read from to determine the health of the link:
| Channel | Register Address |
|---|---|
| A | 0x218 |
For a given channel, read the register value to determine the MSE (Mean Square Error), and see Table 2-11 to determine link quality.
| Link Quality | Register Content |
|---|---|
| Excellent | < 0x20A |
| Good | 0x20A - 0x33B |
| Poor | > 0x33B |
A Time-Domain Reflectometry (TDR) test can also be performed on the PHY to detect problems within the wire's connections and where the fault occurred. For more details regarding different TDR configurations and test modes as well as how to run a TDR test on the PHY, see How to use the TDR Feature of DP83822.