Question

我在verilog编码七段显示器时遇到了一些问题。我希望将1位增加1并在9之后将其翻转为0.我已经进行了大量调试并查看了示例但我似乎无法找到问题。我的代码：

module counter(output sega, segb, segc, segd, sege, segf, segg);

OSCH #("2.08") osc_int (                    //"2.03" specifies the operating frequency, 2.03 MHz. Other clock frequencies can be found in the MachX02's documentation
        .STDBY(1'b0),                           //Specifies active state
        .OSC(clk),                              //Outputs clock signal to 'clk' net
        .SEDSTDBY());

reg [21:0] cnt;
wire clk_slow = cnt[21];  //clock at 1 Hz

reg [3:0] BCD;   //represents the states of the counter
always @(posedge clk) 
begin
    begin
        cnt <= cnt+1;  
    end

    begin
        if(clk_slow) BCD <= (BCD ==4'h9 ? 4'h0 : BCD+4'b0001);   //increments state by 1
    end
end

reg [6:0] seg;  
always @(*)
begin
    case(BCD)
                    //gfedcba

    4'b0000: seg = 7'b1000000; //0
    4'b0001: seg = 7'b1111001; //1
    4'b0010: seg = 7'b0100100; //2
    4'b0011: seg = 7'b0110000; //3
    4'b0100: seg = 7'b0011001; //4
    4'b0101: seg = 7'b0010010; //5
    4'b0110: seg = 7'b0000010; //6
    4'b0111: seg = 7'b1111000; //7
    4'b1000: seg = 7'b0000000; //8
    4'b1001: seg = 7'b0011000; //9
    default seg = 7'b0111111;

    endcase
end

assign {segg, segf, sege, segd, segc, segb, sega} = seg;

endmodule

因此，当它运行时，我的LED会每隔一段时间点亮正确的数字。在这种情况下，它会亮起0,2,4,6,8并重复。在每个数字之间，LED点亮，但不亮（昏暗的'8'）。当我切换机箱的顺序但是将数字保持在同一位置时（例如现在的情况b0000为9号），LED点亮了9,7,5,3,1 ......由于某种原因，我的LED arnt响应任何“奇怪”情况（即0001,0011 ......）。非常感谢任何帮助排序，因为我已经花了很多时间尝试调试。

我正在使用Diamond Lattice FPGA。它有一个板载时钟（我的代码中的第一个模块）。我在clock_slow将它减慢到1赫兹。

Answer 1

您的问题与这些问题有关：

always @(posedge clk) 
begin
    cnt <= cnt+1; 
    if(clk_slow) BCD <= (BCD ==4'h9 ? 4'h0 : BCD+4'b0001);   //increments state by 1
end

由于clk比clk_slow快，因此if条件将在多个时钟周期内为真（'clk_slow为clk个周期的原因BCD为高。这就是always将不止一次递增的原因。我建议你将这两条指令分成两个独立的always @(posedge clk) begin cnt <= cnt + 1; end always @(posedge clk_slow) begin BCD <= (BCD ==4'h9 ? 4'h0 : BCD+4'b0001); //increments state by 1 end块：

#include <pic.h>
#include <stdint.h>
#define _XTAL_FREQ 20000000

void main()
{
   unit8_t pressed = 0;
   bool blink = 0;

   TRISB = 0x01;
   PORTB = 0x00;
   while(1)
   {
       // Button pressed for the first time
       if ((RB0 == 1) && (pressed == 0))
       {
           pressed = 1;
       }
       // Button released = valid 
       else if ((RB0 == 0) && (pressed == 1))
       {
           pressed = 2;
       }

       if (pressed == 2)
       {
          blink ^= 1;
          pressed = 0;
       }

       if (blink == 1)
       {
          PORTB ^= 0xFE;
          __delay_ms(250);
       }
    }
}

七段展示

1 个答案: