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?
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.
The addresses for the LEDs are like this:
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;