Forum: FPGA, VHDL & Verilog 3 bit output

von Ashuuu (Guest)

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I need to design 3 bit output, which are 000, 001, 010, 011, 100 using 
FPGA. I have already designed it. But, the problem is I can't get that 
desired output I want. I got 000, 001, 011 and 111 outputs. Here I 
attach my code and testbench and also Isim simulator waveform part.

Thank you.

von derLars (Guest)

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Hi Ashuuu,

first: the sensitivity list in your module "selectsig" is wrong. The 
whole process is only related to the clock. So only the clock should be 
in the list.

Second: in your testbench. First you assert s0, then you assert s1 -> 
what happens with s0 in that case?

Best regards,

von Ashuuu (Guest)

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Hi derLars,

Do you mean s0, s1, and s0 are output, not the input?

von Chris (Guest)

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You got what you designed.
In your testbench you set s0, s1, s2 to:
0,0,0 then
0,0,1 then
0,1,1 then

Which gives as result in your statemachine:
Don' care.

If you want different outputs you have to set them.

PS, it seems that  you get the desired output by just concatenate the 
input bits in the right oder.


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