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I have a simple VHDL file which can be simulated correctly and that synthesizes with Quartus II-11.0 (web edition). I can interact with switches,leds, seven segments and push buttons.

My problem is that among the 9 Altera DE2 boards I have, only 3 of them behave as expected. The FPGA seems the same...

Visually however, there are little differences on the two kind of boards, but I cannot understand why they don't behave the same :

This one works as expected, while this one does not (notice that e.g capacitors are not the same on the top left).

I am using exactly the same bitstream (pof or sof).

What I am missing ? Where can I find the exact info about these differences ?

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    \$\begingroup\$ What are the differences? \$\endgroup\$ – Some Hardware Guy Jan 18 '13 at 16:43
  • \$\begingroup\$ the differences are : push buttons do not react on 6/9 of the boards, nor probably the sliders \$\endgroup\$ – JCLL Jan 18 '13 at 16:48
  • \$\begingroup\$ what are the differences ? That is my question ! Apparently same "DE2" board with same FPGA "cyclone II C35F672C6N"...so how can I guess the differences ? \$\endgroup\$ – JCLL Jan 18 '13 at 16:51
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    \$\begingroup\$ Are you sure the FPGA part numbers match exactly? Over the last several years I have helped lots of kids with their DE1 issues, and this kind of issue is almost always them selecting the wrong FPGA in the project wizard. \$\endgroup\$ – Matt Young Jan 18 '13 at 17:48
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    \$\begingroup\$ Well, given the environment, perhaps they were quite forceful with the switches/sliders to where they got damaged. Wouldn't be the first time. \$\endgroup\$ – Gustavo Litovsky Jan 19 '13 at 0:10
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I posted my question on altera forum : here

The answer is that it is mandatory to put all unused pins to tri-state.

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  • \$\begingroup\$ So, did changing that constraint fix the problem? \$\endgroup\$ – apalopohapa Jan 20 '13 at 11:06

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