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Altera_Forum's avatar
Altera_Forum
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13 years ago

object assigned a value but never read - does this effect synthesis?

Hello, I have the following small module which is intended to store the value 0xFF in a register when a button is pressed. module connector_test(button, txd); input button; output reg t...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
13 years ago

Check out this link

http://quartushelp.altera.com/11.1/mergedprojects/hdl/vlog/vlog_file_dir_noprune.htm

It gives two ways to use the attribute.

Plus one more way to give a switch through the .qsf file to preserve fanout free node.

In my opinion use the attributes rather than switches.

Coming to the warning i agree with FVM that the attribute will work and the warning will come even though the tool is preserving the registers, as you are not using your signal "data" anywhere in your module.

Check the map.rpt and see whether your register has been preserved.