Tool/software:
Hi All,
Could you please tell me about the loop back function of the DP83867I?
Can the loopback function be used even if the DP83867I is not linked up with the connected PHY?
Best Regards,
Ishiwata
Hi Ishiwata-san,
Can the loopback function be used even if the DP83867I is not linked up with the connected PHY?
MAC-side loopback modes (PCS/MII/...) do not require a link partner, while reverse loopback will require a link partner to route the data back through the cable-side.
Reverse loopback is typically used to validate the MDI signal chain through the cable, e.g. :
PHY1 -> PHY2 (reverse loopback) -> PHY1
PHY1 transmits data, and should receive the same data looped back from PHY2 to validate MDI signal path.
The remaining loopback modes (PCS/MII/...) route the data back to the MAC from varying parts of the PHY's internal DSP blocks. These modes are typically used to validate the MAC-side communication, e.g. :
MAC -> PHY (MII loopback) -> MAC
MAC transmits data, and should receive the same data looped back to validate MAC-side signal path.
Please let me know if I can clarify further.
Thank you,
Evan
