ZHCSKM7G december 2019 – july 2023 DP83826E , DP83826I
PRODUCTION DATA
The DP83826 includes advanced link-drop capabilities that support various real-time applications. The link-drop mechanism is configurable and includes enhanced modes that allow extremely fast link-drop reaction times.
The DP83826 supports an enhanced link-drop mechanism, also called fast link-drop (FLD), which shortens the observation window for determining link. There are multiple ways of determining link status, which can be enabled or disabled based on user preference.
Depending on what mode the DP83826 is in, the default state of FLD will differ. In ENHANCED mode, FLD and all its detection mechanisms are disabled by default through pulling down Strap7. For EtherCAT applications or applications with Fast link drop enabled and expect to handle Baseline wander packets, it is recommended to disable signal energy detect, which can be done by setting Strap8. The table below summarizes the modes enabled by strap.
Strap Configuration | RX Error Count | MLT3 Error Count | Low SNR Threshold | Signal/Energy Loss | Descrambler Link Loss |
---|---|---|---|---|---|
(Default) Strap7 = LOWStrap1 = X Strap8 = X | Disabled | Disabled | Disabled | Disabled | Disabled |
Strap7 = HIGH Strap1 = HIGH Strap8 = LOW | Enabled | Enabled | Enabled | Enabled | |
Strap7 = HIGH Strap1 = LOW Strap8 = LOW | Enabled | Disabled | Enabled | Disabled | |
Strap7 = HIGH Strap1 = LOW Strap8 = HIGH | Enabled | Disabled | Disabled | Disabled |
In BASIC mode, fast link-drop is enabled by default. The default mechanisms in BASIC mode will be RX error and signal/energy loss.
In both modes, FLD can be configured using the Control Register #3 (CR3, register address 0x000B). Bits[3:0] and bit[10] allow for various FLD conditions to be enabled. When link-drop occurs, indication of a particular fault condition can be read from the Fast Link Drop Status Register (FLDS, register address 0x000F).
Fast link-drop criteria include:
The fast link-drop functionality allows the use of each of these options separately or in any combination.