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Valued Contributor III
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DE0 NANO running LED schematic design not running as expected

I just bought a DE0-Nano Development and Education Board from: 

http://www.terasic.com.tw/cgi-bin/page/archive.pl?language=english&no=593 

 

This is my first FPGA. 

I use Quartus II 32-bit Version 13.0.1 Web Edition 

Start with a simple design I made a running LED 

- Use the on-board oscillator. PLL and lpm counter to make the frequency lower 

- another lpm counter to feed the lpm decode. 

- lpm decode to output the running LED 

running OK 

 

Then I tried add a DFF to make the running LED bidirectional (see my pic). 

- The DFF is controlled by the lpm decode edge output. The DFF output is controlling the lpm counter. 

 

The running LED is not running as I expected. The led7 only ON at startup and never reach back. 

So it run with sequence like this from startup: 

led7 - led6 - led5 - led4 - led3 - led2 - led1 - led0 - led1 - led2 - led3 - led4 - led5 - led6 - led5 - led4 - ... (not reaching led7) 

 

Something wrong in my design? 

http://www.alteraforum.com/forum/attachment.php?attachmentid=12201&stc=1
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