[Serialization] example of FPGA Series-8-3 priority encoder

8-3 encoder with priority in each node

Principle:

In a digital system, several parts may send service requests at the same time, but at the same time, only one of them can send a permitted operation signal. Therefore, you must set priorities for the operation permitted by these control objects, that is, the priority level.

The encoder has 8 inputs and 3 outputs. There is also an input enable EI, output enable EO and priority encoder working status mark GS. Encoder is effective at low cost. When EI = 0, the encoder works; the output is all high. The input priorities are 7, 6, 5 ,..., 0. When a low-level input has a lower-level input, and the input with a higher priority has no lower-level input, the output end outputs the code of the corresponding input.

II. Implementation

Enter the OpenGL code in the design file.

 1   `timescale 1 ns / 1 ps
 2 
 3 module yxbm8_3 ( A ,I ,GS ,EO ,EI );
 4 
 5 input [7:0] I ;
 6 wire [7:0] I ;
 7 input EI ;
 8 wire EI ;
 9 
10 output [2:0] A ;
11 reg [2:0] A ;
12 output GS ;
13 reg GS ;
14 output EO ;
15 reg EO ;
16 
17 always @ ( I  or EI )
18     if ( EI )
19         begin 
20             A <= 3'b111;
21             GS <= 1;
22             EO <= 1; 
23         end
24     else if ( I[7] == 0 )  
25           begin 
26             A <= 3'b000;
27             GS <= 0;
28             EO <= 1; 
29             end
30     else if ( I[6] == 0 ) 
31         begin 
32                A <= 3'b001;
33             GS <= 0;
34             EO <= 1; 
35         end
36     else if ( I[5] == 0 ) 
37         begin 
38                A <= 3'b010;
39             GS <= 0;
40             EO <= 1; 
41         end
42     else if ( I[4] == 0 ) 
43         begin 
44                A <= 3'b011;
45             GS <= 0;
46             EO <= 1; 
47         end
48       else if ( I[3] == 0 ) 
49         begin 
50              A <= 3'b100;
51             GS <= 0;
52             EO <= 1; 
53         end
54      else if ( I[2] == 0 ) 
55         begin 
56               A <= 3'b101;
57             GS <= 0;
58             EO <= 1; 
59         end
60      else if ( I[1] == 0 ) 
61         begin 
62                A <= 3'b110;
63             GS <= 0;
64             EO <= 1;   
65             end
66       else if ( I[0] == 0 ) 
67         begin 
68              A <= 3'b111;
69             GS <= 0;
70             EO <= 1; 
71         end
72         else if ( I == 8'b11111111)      
73             begin 
74               A <= 3'b111;
75             GS <= 1;
76             EO <= 0; 
77         end
78 endmodule