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Altera_Forum
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17 years ago

Dangerous bug in DE2-70 demonstrations

If I'm not mistaken, there is a very serious bug on several of the DE2-70 demonstrations that could create bus contention in one signal. It seems to affect all NIOS based designs except the Control P...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
17 years ago

I am trying to contact Terasic, but without success so far.

The fix is simple. Edit the top module of the design (i.e.: DE2_70_NET.v). Find the following line: 

assign AUD_ADCLRCK = AUD_DACLRCK;

Replace with a permanent tri-state assignment: 

assign AUD_ADCLRCK = 1'bz;

This should be done on all the designs that use the audio codec in master mode. Seems all NIOS samples do, and seems all have the bug except the Control Panel.

Note that in same cases there are two identical lines with the assignment causing the bug, one is commented and the other is not. This was possibly, the origin of the bug.

Check the fitter report to verify the bug was fixed. The AUD_ADCLRCK pin should have a permanently disabled output enable.