I can program LEDs 0 to 3 to light up, but I get an error when I try to assign LEDs 4 to 7. Why is that?
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asked Mar 10, 2011 at 22:09
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\$\begingroup\$ What is a Nexsys2 board? \$\endgroup\$– Leon HellerCommented Mar 10, 2011 at 23:04
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\$\begingroup\$ Betting it should have been Nexys2? \$\endgroup\$– KellenjbCommented Mar 10, 2011 at 23:08
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\$\begingroup\$ digilentinc.com/Products/Detail.cfm?Prod=NEXYS2 \$\endgroup\$– Leon HellerCommented Mar 10, 2011 at 23:15
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1\$\begingroup\$ What error do you get? \$\endgroup\$– Nick TCommented Mar 10, 2011 at 23:26
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3\$\begingroup\$ Load the self test program, it lets you switch all LEDs on and off via the corresponding slide switches. If you can switch on the LEDs that way, then nothing is wrong with your board. \$\endgroup\$– freespaceCommented Mar 11, 2011 at 11:59
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2 Answers
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LD4 is connected to both E16 and E17 and LD5 is connected to both P15 and P16, which is rather strange. There is a similar problem with LD6 and LD7. Perhaps you have to enable both outputs in each case. It might be best to contact Digilent support about the anomaly.
answered Mar 10, 2011 at 23:28
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1\$\begingroup\$ This isn't true. The UCF at first glance appears to say this, but it doesn't: for s3e500 led4 is connected to E17, otherwise E16. This is true for led4-led7. You need to comment out definition line that doesn't match the chip you have on the board. \$\endgroup\$ Commented Mar 11, 2011 at 12:05
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\$\begingroup\$ I was going off the schematic, it should have a note against those connections about the PCB being suitable for two versions of the FPGA. \$\endgroup\$ Commented Mar 11, 2011 at 15:09
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The addresses for the LEDs are like this:
P4,E4,P16,E16,K14,K15,J15,J14
Apparently the following code can be used to test them:
(* LOC="P4,E4,P16,E16,K14,K15,J15,J14" *) output reg [7:0] LEDs=0;
answered Mar 18, 2011 at 20:53