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Does anybody know verilog?

  1. Apr 17, 2008 #1
    Hi. I'm new to verilog and I'm trying to do something that to me, seems very simple. I have a file with some logic and outputs, and all I want is for the outputs to hold their values, like registers.

    In other words, if output = 001, I want it to stay that way until it is re-assigned. The problem I am having, is that verilog won't let me assign my output or a wire to a register value.

    Here is my code so far:
    Code (Text):
    module coin_input(CI, button_out_signal, button_in);
        output [1:0] CI;
        output button_out_signal;
        input [3:0] button_in;
        wire [2:0] button_id;
        reg [1:0] CItemp;
        wire [1:0] CItemp2;
        assign CI[1] = CItemp2[1];
        assign CI[0] = CItemp2[0];
        assign CItemp2[1] = CItemp[1];
        assign CItemp2[0] = CItemp[0];
        //Connect buttons to button stabilizers
        //Button_Stabilizer(button_out, button1_in, enter)
        Button_Stabilizer   bs2(button_id[2], button_in[3], button_in[0]),
                            bs1(button_id[1], button_in[2], button_in[0]),
                            bs0(button_id[0], button_in[1], button_in[0]);
        //Convert button_id's to CI to give precedence to higher-value coins
        always @(posedge button_in[3]) begin
            {CItemp[1], CItemp[0]} <= 2'b11;
        always @(posedge button_in[2]) begin
            {CItemp[1], CItemp[0]} <= 2'b10;
        always @(posedge button_in[1]) begin
            {CItemp[1], CItemp[0]} <= 2'b01;

        //Set button_out_signal to 1
        assign button_out_signal = button_in | 1'b0;
    You can see that I am using the register CItemp to hold the values that I want to store. I want to assign the output, CI, to this register value. How in the world do I do that?
  2. jcsd
  3. Apr 17, 2008 #2
    I'm really very sorry, but I believe I have figured out what I was doing wrong above. I've traced it back to a different issue, actually.

    The problem is that I have a circuit with three different inputs, and the circuit is supposed to react based on a positive edge from any of the inputs. For example, if input1 has a positive edge, the output should be set to 01. If input2 has a positive edge, the output should be set to 10.

    I am having a serious issue coding this. I have one procedural statement to excute a bunch of code when there is a positive edge in either input:
    Code (Text):
    always @(posedge button_id[2] or posedge button_id[1] or posedge button_id[0]) begin
    But, I am not able to write good logic after that, because once inside that procedural statement, how can the code be aware of WHICH input generated a positive edge?
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