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AR# 260

XBLOX 5.x: Implementing DATA_REG in IOB resources


Keywords: XBLOX, data_reg, IOB

Urgency: Standard

General Description:

How do I force DATA_REG to be implemented in an I/O block?


The following STYLE attributes, new in XACT 5.0, are available on the
DATA_REG module to control where the DATA_REG flip-flops are placed.

* STYLE=IOB: Implement as either IFDs or OFDs (input FF or output FF)
* STYLE=IFD: Implement as IFDs (input FFs)
* STYLE=OFD: Implement as OFDs (output FFs).
* STYLE=ILD: Implement as ILDs (level-sensive input latches)
* STYLE=CLB: Implement in CLB FFs

If you do not specify a style, XBLOX will select the appropriate style
based on how the DATA_REG is connected. For example, in an XC4000, if the
DATA_REG is connected to an INPUTS symbol and does not use a clock enable,
the DATA_REG will be merged into the input flip-flops. Otherwise, the
DATA_REG will use CLB flip-flops.
AR# 260
Date 05/24/1999
Status Archive
Type General Article
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