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AR# 29118

9.2i System Generator - How do I use the Viterbi block with discontinuous input data, or data at a slower rate?

Description

How do I use the System Generator Viterbi block with discontinuous data, or data at a slower rate?

Solution

The Vin/Vout ports on the System Generator Viterbi block correspond to the Block_in/ Block_out ports on the Virterbi Core and should not be used to facilitate discontinuous input data, or input data at a slower rate.

The System Generator Viterbi block has an EN input port that is connected to the CE port of the Viterbi Core and this port should be used to "freeze" the core when needed. From the Viterbi data sheet: "When CE is deasserted (Low), all synchronous inputs are ignored and the core remains in its current state. The state of the core is frozen while CE is Low."

When using the core with data at a slower rate, the EN input port can be used as a clock enable port to slow the block down.

There was a problem with the System Generator wrapper for Viterbi v5.0 and discontinuous data will not work with this version. You can bring in v5.0 of the Viterbi Core with a black box to work around this issue. Also, v6.0 of the Viterbi Core does not have this issue and is now available in System Generator.

AR# 29118
Date Created 11/26/2007
Last Updated 12/15/2012
Status Active
Type General Article