CODEWITHSUNDEEP
verilogfpgaxilinx
Nic
Nic

Reputation: 93

Push button link with blink LED

I'm very new to HDL coding. I'm using Xilinx verilog for HDL coding.

I'm trying to implement a push btn to activate the LED blinking code below and when button is released, blinking stops. Below is the blinking LED code

`timescale 1ns / 1ps
module blinkyslow(
    input CLOCK, SW,
    output LED
    );
    reg [24:0] COUNT = 25'b0000000000000000000000000;
    reg LED=1;
    always @(posedge CLOCK) begin
    COUNT <= COUNT + 1;
    LED <= (COUNT == 25'b0000000000000000000000000)?~LED:LED;
    end
endmodule

I'm using basys 3 board and i'm trying to link variable SW as the switch

Upvotes: 2

Views: 3940

Answers (3)

Hamid
Hamid

Reputation: 311

You can use this code: 

`timescale 1ns / 1ps  
module blinkyslow(  
    input CLOCK, SW,reset,  
    output reg LED  
    );  
    reg [24:0] COUNT;  
    always @(posedge CLOCK) begin  
      if ( reset ==1'b1)  
        LED <= 1'b0;
        COUNT <= 0;
      else  
        begin  
    COUNT <= COUNT + 1;  
    LED <= SW & ((COUNT == 25'b0)?~LED:LED);  
        end  
      end  
endmodule

Since the always block is only sensitive to the rising edge of the CLOCK signal, the reset signal is a synchronous reset.

Upvotes: 2

Sourabh
Sourabh

Reputation: 674

@Nicholas Chan. In your original code, you have defined the following line not in initial block. Hence, LED is hardwired to zero.

reg LED=1;

so either define a reset signal for LED and COUNT (as in earlier answer )or you can try using the following code using initial block

timescale 1ns / 1ps module blinkyslow( input CLOCK, SW, output LED ); initial:begin reg [24:0] COUNT = 25'b0000000000000000000000000; reg LED=1; end always @(posedge CLOCK) begin COUNT <= COUNT + 1; LED <= (COUNT == 25'b0000000000000000000000000)?~LED:LED; end endmodule

Upvotes: 0

MikeCAT
MikeCAT

Reputation: 75062

For example, you can implement it by having the counter increment only if the button is pressed.

(Strictly speaking, this is not good because if COUNT stays zero, LED will be toggled at evely clock. Toggling LED only if the button is pressed will solve this)

`timescale 1ns / 1ps
module blinkyslow(
    input CLOCK, SW,
    output LED
    );
    reg [24:0] COUNT = 25'b0000000000000000000000000;
    reg LED=1;
    always @(posedge CLOCK) begin
        if (SW) begin
            COUNT <= COUNT + 1;
            LED <= (COUNT == 25'b0000000000000000000000000)?~LED:LED;
        end
    end
endmodule

(not tested, assuming SW = 1 means the switch on the board is pressed)

Upvotes: 1

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