用Verilog实现串并转换/并串装换

摘要

一、串并转换模块

       串转并就是将低3位信号和输入信号一起赋值。因为经过转换后，码元速率会将为原来四分之一，所以设置4分频时钟，将其输出。而并转串就是不断右移，取高位输出。

module serial2para(input clk, rst_n,input ser_data_in,output reg [3:0] para_data_out
);parameter N = 4;//四分频模块
reg [13:0]  cnt;
reg         clk_out;
reg [3:0]   data;always @(posedge clk or negedge rst_n) beginif(cnt == N/2 - 1) begincnt     <= 14'b0;clk_out <= ~clk_out;end elsecnt <= cnt + 1'b1;
endalways @(posedge clk or negedge rst_n) beginif(~rst_n) data <= 4'h0;else       data <= {data[2:0], d};
endalways @(posedge clk_out or negedge rst_n) beginif(~rst_n) para_data_out <= 4'h0;else       para_data_out <= data;
endendmodule

1.1 利用移位寄存器

        串行转并行数据输出：采用位拼接技术（移位寄存器），将串行的数据总数先表示出来，然后发送一位数据加一，后面的接收的这样标志：para_data_o <= {para_data_o[6:0], ser_data_i };

module serial_parallel #(parameter DATA_WIDTH     = 8
)(input                          clk,input                          rst_n,input                          left_shift,input                          ser_data_in,   //1位串行输入output                         valid,output reg [DATA_WIDTH-1:0]    para_data_o	//8位并行输出
);parameter CNT_WIDTH = $clog2(DATA_WIDTH);reg [CNT_WIDTH-1:0]              ser_bit_cnt;always @(posedge clk or negedge rst_n) beginif (~rst_n)para_data_o <= {DATA_WIDTH{1'b0}};else if (left_shift == 1'b1)para_data_o <= {para_data_o[DATA_WIDTH-2:0], ser_data_in};	//低位先赋值，左移else if(left_shift == 1'b0)para_data_o <= {ser_data_in, para_data_o[DATA_WIDTH-1:1]};	//高位先赋值,右移
endalways @(posedge clk or negedge rst_n) beginif(~rst_n) beginser_bit_cnt <= {CNT_WIDTH{1'b0}};valid       <= 1'h0;endelse if(ser_bit_cnt == DATA_WIDTH-1) beginser_bit_cnt <= {CNT_WIDTH{1'b0}};valid = 1'b1;endelse beginser_bit_cnt <= ser_bit_cnt + 1'b1;valid       <= 1'b0;end
endendmodule

1.2 利用计数器

        利用计数器cnt 时钟计数，开始数据先给高位，每过一个时钟周期，数据便给低一位。这样便可以达到串转并的效果。

module serial_parallel(parameter         DATA_WITH = 8
)(input                      clk,input                      rst_n,input                      ser_data_in,input                      valid,output reg [DATA_WITH-1:0] para_data_o
);parameter                      CNT_WIDTH = $clog2(DATA_WITH);//msb first   most significant bit 表示二进制数据的最高位
reg   [DATA_WITH-1:0]   cnt; 	//计数器0-7  always @(posedge clk or negedge rst_n)beginif(rst_n == 1'b0) beginpara_data_o <= {DATA_WITH{1'b0}};cnt <= {CNT_WIDTH{1'd0}};endelse beginpara_data_o[DATA_WITH-1 - cnt] <= ser_data_in;	//高位先赋值cnt <= cnt + 1'b1;end
end/*
//lsb first	(least significant bit) 表示二进制数据的最低位reg     [2:0]   cnt;always @(posedge clk or negedge rst_n)beginif(rst_n == 1'b0) beginpara_data_o <= {DATA_WITH{1'b0}};cnt <= {CNT_WIDTH{1'd0}};endelse beginpara_data_o[cnt] <= data_i;   //低位先赋值cnt <= cnt + 1'b1;end
end
*/endmodule