Verilog 之随机波形产生-可综合

// Poisson process generator.

// Generate Poisson process with desired inversed rate (number of clocks per hit).

// The rate is defined by parameter LN2_PERIOD. For example, the LN2_PERIOD=4 will generate

// in average one pulse per 16 clocks.

目的：产生Poisson 分布的随机数

方法：Verilog ；LFSR伪随机数发生器 ；

程序part1：LFSR伪随机数发生器

module pseudo_random(input  clk, ce, rst, output reg [31:0] q);
// 32-bit uniform pseudo-random number generator, based on fibonacci LFSR
// Other 32-bit uniform random generators can be used as well.

wire feedback = q[31]^q[29]^q[28]^ q[27]^ q[23]^q[20]^ q[19]^q[17]^ q[15]^q[14]^q[12]^ q[11]^q[9]^ q[4]^ q[3]^q[2];
//feedback term B89ADA1C, other terms can be found from this table
// http://www.ece.cmu.edu/~koopman/lfsr/index.html 
always @(posedge clk or posedge rst)
if (rst)    //高电平复位
q <= 32'haaaaaaaa;   // the start is more random with this initialization
else if (ce)
q <= {q[30:0], feedback} ;
endmodule

程序part2：

module random_pulse_generator( input clk, ce, rst, output reg q);

parameter LN2_PERIOD = 4; // 1 < LN2_PERIOD < 31
// log2 of the inversed process rate ,

parameter MASK = {LN2_PERIOD{1'b0}}; // any number with LN2_PERIOD bits can be used as a MASK
wire [31:0] uniform_random;
wire [LN2_PERIOD-1:0] sample;
pseudo_random pseudo_random_gen(clk, ce, rst, uniform_random);

assign sample = uniform_random[LN2_PERIOD-1:0]; // any subset of LN2_PERIOD bits can be used as a sample
always @ (posedge clk)
if(ce) begin
if (sample == MASK) q <= 1'b1;
if (q) q <= 1'b0;
end
endmodule

程序modelsim仿真: