:FUNCtion:PARameters:DFEQualizer:SEED

Command Syntax

:FUNCtionN:PARameters:DFEQualizer:SEED {ON | OFF | 1 | 0}

Where N identifies one of sixty four {1:64} math functions that you can create. For example, :FUNCtion2.

Query Syntax

:FUNCtionN:PARameters:DFEQualizer:SEED

Query Response

{1 | 0}

Description

Normally DFE will exclude the first several symbols from the real-time eye because they are used to seed the DFE. For example, if you are using a 4-tap DFE, the first four UIs are not included in the real-time eye.

However, if you want to include all of the unit intervals in the real-time eye, you can use this command to enable seeding of DFE taps.

When enabled, initial symbols are all seeded to the Seed Value (see :FUNCtion:PARameters:DFEQualizer:SEED:VALue) so that the DFE can start working on the first UI.

DFE tap seeding is useful for DDR buses that turn on and off frequently.

When read-write separation is used to generate a real-time eye for DDR read or write bursts, there are bursts of DQS (Strobe) clocks associated with the bursts of read or write data, and then there are intervals with no clocks between bursts. DFE taps need to be reseeded after intervals with no clocks, so there is the Clock Idle Reseed Time command (see :FUNCtion:PARameters:DFEQualizer:SEED:RTIMe) for specifying the time between clocks after which the DFE needs to be reseeded. This value should be slightly less than the smallest time between the end of one burst and the beginning of the next. If you do not want the DFE to be reseeded after intervals with no clocks, you can simply enter a really long "time to exceed".