Xilinx FPGA:vivado关于真双端口的串口传输数据的实验
一、实验内容
用一个真双端RAM，端口A和端口B同时向RAM里写入数据0-99，A端口读出单数并存入单端口RAM1中，B端口读出双数并存入但端口RAM2中，当检测到按键1到来时将RAM1中的单数读出显示到PC端，当检测到按键2到来时，将RAM2中的双数显示到pc端。
二、信号流向图
TIPS：这里我本来想将single_ram_1和single_ram_2分成两个单独的模块，但是经过实验后发现，如果分成两个单独的模块的话会导致：
①两个单端RAM模块的tx_start（0或1）都会有值给uart_tx模块，即使是RAM1给【1】，RAM2中没有值【0】，uart_tx模块是无法判断 tx_start 到底来自于哪个模块，所以此时uart_tx模块只是能接收到一个tx_start的脉冲信号，但是无法判断信号来自哪个RAM模块，无法获取到相应的uart_data ,最终导致tx_flag都无法变成高电平，那就更不会返回给RAM模块tx_done信号了。
②如果单独为了正确信号能赋值给tx_start而重新去写一个ctrl模块的话，那么在ctrl模块中将无法使用判断条件，因为我们将状态作为了赋值条件而不仅仅是key_flag信号。
那么我的解决方法就是把single_ram_2例化到single_ram_1当中，将single_ram_2输出的数据（uart_data_b及tx_start_b）和single_ram_1输出的数据（douta即tx_start_a）全部放在一个模块即single_ram_1中去做判断，但是我们仍然无法将single_ram_2的状态作为赋值的条件，所以只能采用这种比较粗暴的方式，也就是除了（ cur_state == REG || cur_state == READ ）时候tx_start <= tx_start_a ;那么其他情况就是tx_start <= tx_start_b ; uart_data的处理也是同样。详见后面程序。
其实最好的方式是将single_ram_2和single_ram_1写在同一个模块中，程序放在文章最后了。
三、程序设计
（1）按键消抖模块：
这里注意key1和key2不能使用同一个计数器，不然在同一个模块中也会判断出问题。
`timescale 1ns / 1ps
module key_debounce(input sys_clk ,input rst_n ,input key1 ,input key2 ,output key_flag_1 ,output key_flag_2);
// parameter delay = 100_000_0 ; //20msparameter delay = 100;// 测试用reg[19:0] cnt1 ;reg[19:0] cnt2 ;key_flag_1 always@(posedge sys_clk )if(!rst_n)cnt1 <= 0 ;else if ( key1 == 0 )beginif ( cnt1 == delay -1 )cnt1 <= cnt1 ;else cnt1 <= cnt1 +1 ;endelsecnt1 <= 0 ;assign key_flag_1 = ( cnt1 == delay -2 )?1:0 ;///key_flag_2always@(posedge sys_clk )if(!rst_n)cnt2 <= 0 ;else if ( key2 == 0 )beginif ( cnt2 == delay -1 )cnt2 <= cnt2 ;else cnt2 <= cnt2 +1 ;endelsecnt2 <= 0 ;assign key_flag_2 = ( cnt2 == delay -2 )?1:0 ; endmodule
（2）真双端模块：
IP参数：
`timescale 1ns / 1ps
module the_true_ram(input sys_clk ,input rst_n ,output [7:0] ram_odd_data ,output [7:0] ram_even_data);A端口reg wea ;reg [6 : 0] addra ;reg [7 : 0] dina ;wire [7 : 0] douta ;always@(posedge sys_clk )if(!rst_n)wea <= 0 ;else if ( addra >= 99 )wea <= 0 ;elsewea <= 1 ;always@(posedge sys_clk )if(!rst_n)addra <= 0 ;else if ( addra >= 99 )addra <= 99 ;elseaddra <= addra +1 ;always@(posedge sys_clk )if(!rst_n)dina <= 0 ;else if (dina >= 99)dina <= 99 ;elsedina <= dina +1 ;wire [7:0] data_a ;assign data_a = douta ;assign ram_odd_data = (data_a%2 == 1)?data_a : ram_odd_data ;///b端口reg web ; reg [6 : 0] addrb ;reg [7 : 0] dinb ;wire [7 : 0] doutb ;always@(posedge sys_clk )if(!rst_n)web <= 0 ;else if ( addrb >= 99 )web <= 0 ;elseweb <= 1 ;always@(posedge sys_clk )if(!rst_n)addrb <= 0 ;else if ( addrb >= 99 )addrb <= 99 ;elseaddrb <= addrb +1 ;always@(posedge sys_clk )if(!rst_n)dinb <= 0 ;else if ( dinb >= 99 )dinb <= 99 ;elsedinb <= dinb +1 ;wire[7:0] data_b ;assign data_b = doutb ;assign ram_even_data = (data_b %2 == 0 )? data_b : ram_even_data ;//----------- Begin Cut here for INSTANTIATION Template ---// INST_TAG
true_ram your_instance_name (.clka(sys_clk ), // input wire clka.ena(1), // input wire ena.wea(wea), // input wire [0 : 0] wea.addra(addra), // input wire [6 : 0] addra.dina(dina), // input wire [7 : 0] dina.douta(douta), // output wire [7 : 0] douta.clkb(sys_clk ), // input wire clkb.enb(1), // input wire enb.web(web), // input wire [0 : 0] web.addrb(addrb), // input wire [6 : 0] addrb.dinb(dinb), // input wire [7 : 0] dinb.doutb(doutb) // output wire [7 : 0] doutb
);
// INST_TAG_END ------ End INSTANTIATION Template ---------endmodule
（3）单端RAM2模块：
但其实深度在50就够用了。（100里面的奇数和偶数50）
`timescale 1ns / 1ps
module single_ram_2_FMS(input sys_clk ,input rst_n ,input key_flag_2 ,input tx_done ,input [7:0] ram_even_data ,output reg tx_start_b ,output reg[7:0] uart_data_b);存双数的RAMreg ena ;reg [0 : 0] wea ;reg [6 : 0] addra ;reg [7 : 0] dina ;wire [7 : 0] douta ;//先写再读出localparam IDLE = 3'd0 ;localparam WRITE = 3'd1 ;localparam REG = 3'd2 ;localparam READ = 3'd3 ;reg[2:0] cur_state ;reg[2:0] next_state ;//state1always@(posedge sys_clk )if(!rst_n)cur_state <= IDLE ;else cur_state <= next_state ;//state2always@(*)case(cur_state)IDLE :beginnext_state = WRITE ;endWRITE :beginif ( key_flag_2 )next_state = REG ;elsenext_state = cur_state ;endREG :beginnext_state = READ ;endREAD :beginif(addra == 49)next_state = IDLE ;elsenext_state <= cur_state ;enddefault:;endcase//state3always@(posedge sys_clk )if(!rst_n)beginena <= 0 ;wea <= 0 ;addra <= 0 ;dina <= 0 ;tx_start_b <= 0 ;endelsecase(cur_state)IDLE :beginena <= 0 ;wea <= 0 ;addra <= 0 ;dina <= ram_even_data ;endWRITE :beginena <= 1 ;wea <= 1 ;if(addra == 49)addra <= 49 ;elseaddra <= addra +1 ;dina <= ram_even_data ;endREG :beginaddra <= 0 ;ena <= 0 ;wea <= 0 ;dina <= 0 ;tx_start_b <= 1 ;endREAD :beginena <= 1 ;wea <= 0 ;dina<= 0 ;if(tx_done)begintx_start_b <= 1 ;addra <= addra +1 ;endelse begintx_start_b <= 0 ;addra <= addra ;endenddefault:;endcase//----------- Begin Cut here for INSTANTIATION Template ---// INST_TAG
single_ram ram2 (.clka(sys_clk ), // input wire clka.ena(ena), // input wire ena.wea(wea), // input wire [0 : 0] wea.addra(addra), // input wire [6 : 0] addra.dina(dina), // input wire [7 : 0] dina .douta(douta) // output wire [7 : 0] douta
);
// INST_TAG_END ------ End INSTANTIATION Template ---------always@(posedge sys_clk )if(!rst_n)uart_data_b <= 0 ;else if ( cur_state == READ )uart_data_b <= douta ;elseuart_data_b <= uart_data_b ;always@(posedge sys_clk )if(!rst_n)tx_start_b <= 0 ;else if ( cur_state == REG || cur_state == READ )tx_start_b <= 1 ;elsetx_start_b <= tx_start_b ; endmodule
（4）单端RAM1模块
配置和前面一样
`timescale 1ns / 1ps
module single_ram_1_FMS(input sys_clk ,input rst_n ,input key_flag_1 ,input key_flag_2 ,input tx_done ,input[7:0] ram_odd_data ,input[7:0] ram_even_data,output reg tx_start ,output reg[7:0] uart_data );/读单数的RAMreg ena ; reg wea ;reg [6 : 0] addra ;reg [7 : 0] dina ;wire [7 : 0] douta ;reg tx_start_a ;wire tx_start_b ; wire[7:0] uart_data_b ; 先写再读出localparam IDLE = 3'd0 ;localparam ERITE = 3'd1 ;localparam REG = 3'd2 ;localparam READ = 3'd3 ;reg[2:0] cur_state ;reg[2:0] next_state ;//state1always@(posedge sys_clk )if(!rst_n)cur_state <= IDLE ;elsecur_state <= next_state ;//state2always@(*)case(cur_state)IDLE :beginnext_state = ERITE ;endERITE :beginif(key_flag_1)next_state = REG ;elsenext_state <= cur_state ;endREG :beginnext_state = READ ;//用来发送tx_startendREAD :beginif(addra == 49)//100内的单数是50next_state = IDLE ;elsenext_state = cur_state ;enddefault:;endcase//state3always@(posedge sys_clk )if(!rst_n)beginena <= 0 ;wea <= 0 ;addra<= 127 ;dina <= 0 ;tx_start_a <= 0 ;endelsecase(cur_state)IDLE :beginena <= 0 ;wea <= 0 ;addra<= 7'd127 ;dina <= ram_odd_data ;endERITE :beginena <= ~ena ;wea <= ~wea ;if( addra == 49 && wea)addra <= 49 ;else if(wea)addra <= addra +1 ;dina <= ram_odd_data ;endREG :beginena <= 0 ; wea <= 0 ; addra<= 0 ; dina <= 0 ; tx_start_a <= 1 ; endREAD :beginena <= 1 ;wea <= 0 ;dina<= 0 ;if(tx_done)begintx_start_a <= 1 ;addra <= addra +1 ;endelse begintx_start_a <= 0 ;addra <= addra ;endenddefault:;endcase//----------- Begin Cut here for INSTANTIATION Template ---// INST_TAG
single_ram ram1 (.clka(sys_clk ), // input wire clka.ena(ena), // input wire ena.wea(wea), // input wire [0 : 0] wea.addra(addra), // input wire [6 : 0] addra.dina(dina), // input wire [7 : 0] dina.douta(douta) // output wire [7 : 0] douta
);
// INST_TAG_END ------ End INSTANTIATION Template ---------always@(posedge sys_clk )if(!rst_n)uart_data <= 0;else if ( cur_state == READ )uart_data <= douta ;elseuart_data <= uart_data_b ;always@(posedge sys_clk )if(!rst_n)tx_start <= 0 ;else if ( cur_state == REG || cur_state == READ )tx_start <= tx_start_a ;elsetx_start <= tx_start_b ; 例化ram2 single_ram_2_FMS single_ram_2_FMS_u(. sys_clk (sys_clk ) ,. rst_n (rst_n ) ,. key_flag_2 (key_flag_2 ) ,. tx_done (tx_done ) ,. ram_even_data (ram_even_data) ,. tx_start_b (tx_start_b ) ,. uart_data_b (uart_data_b )); endmodule
（5）uart_tx模块：
`timescale 1ns / 1ps
module uart_tx(input sys_clk ,input rst_n ,input wire[7:0] uart_data ,input rx_done , output reg tx_data , output reg tx_done);parameter SYSCLK = 50_000_000 ;parameter Baud = 115200 ;parameter COUNT = SYSCLK/Baud ;//434 传输1比特所需要的时钟周期parameter MID = COUNT/2 ;wire start_flag ;reg tx_flag ;reg tx_reg1 ;reg tx_reg2 ;reg[4:0] cnt_bit ;reg[10:0] cnt ;//tx_startalways@(posedge sys_clk)if(!rst_n)begintx_reg1 <= 0 ;tx_reg2 <= 0 ;endelse begintx_reg1 <= rx_done ;tx_reg2 <= tx_reg1 ;endassign start_flag = tx_reg1 & ~tx_reg2 ;///tx_flagalways@(posedge sys_clk)if(!rst_n)tx_flag <= 0 ;else if ( start_flag == 1 )tx_flag <= 1 ;else if ( cnt == COUNT -1 && cnt_bit == 10)
// else if ( cnt == MID -1 && cnt_bit == 10)tx_flag <= 0 ;elsetx_flag <= tx_flag ;///计时器// cnt 434 always@(posedge sys_clk )if(!rst_n)cnt <= 0;else if ( tx_flag == 1 )beginif ( cnt == COUNT -1) ///一定要减一，如果不减一，实际会计到435次，反算回去波特率就不是115200了cnt <= 0;elsecnt <= cnt +1 ;endelsecnt <= 0 ;// /计数器always@(posedge sys_clk )if(!rst_n)cnt_bit <= 0 ;else if ( tx_flag )beginif ( cnt == COUNT -1)beginif(cnt_bit == 10)///0123456789 10cnt_bit <= 0 ;elsecnt_bit <= cnt_bit +1 ;endelsecnt_bit <= cnt_bit ;endelsecnt_bit <= 0 ;parameter MODE_CHECK = 0 ;always@(posedge sys_clk )if(!rst_n)tx_data <= 1 ; //表示没有数据else if ( tx_flag )beginif ( cnt_bit > 0 && cnt_bit < 9 )///cnt_bit 0 12345678 9 ///tx_data 0123456789///uart_data 01234567tx_data <= uart_data [cnt_bit-1]; //这里uart_data是不断随着cnt_bit变化的，只有在第九位的时候才有正确的最终值else if(cnt_bit == 0)tx_data <= 0 ;else if(cnt_bit == 9)tx_data <= (MODE_CHECK == 0)? ^uart_data: ~^uart_data;/*MODE_CHECK == 0是偶校验，假如uart_data是1110_0000，其异或的结果是1，将异或的结果作为校验位，让数据位和校验位异或的结果为0，满足偶校验。假如uart_data是1110_1000，其异或的结果是0，将异或的结果作为校验位，让数据位和校验位异或的结果为0，满足偶校验。奇校验则相反。*/else if (cnt_bit == 10)///停止位tx_data <= 1 ;elsetx_data <= tx_data ;endelsetx_data <= 1 ;always@(posedge sys_clk )if(!rst_n) tx_done <= 0 ;else if (tx_flag)beginif ( cnt_bit == 10 && cnt == COUNT -1)
// if ( cnt_bit == 10 && cnt == MID/2 -1)tx_done <= 1 ;elsetx_done <= 0 ; endelsetx_done <= 0 ;
endmodule四、仿真模块
（1）仿真true_ram模块
代码：
`timescale 1ns / 1ps
module test_the_true_ram( );reg sys_clk ;reg rst_n ;wire [7:0] ram_odd_data ;wire [7:0] ram_even_data ;initialbeginsys_clk = 0 ;rst_n = 0 ;#10 rst_n = 1 ;endalways #1 sys_clk = ~sys_clk ; the_true_ram the_true_ram_1(. sys_clk (sys_clk ) ,. rst_n (rst_n ) ,. ram_odd_data (ram_odd_data ) ,. ram_even_data (ram_even_data));endmodule
仿真结果：
（2）仿真TOP：
代码：
`timescale 1ns / 1ps
module test_TOP( );reg sys_clk ;reg rst_n ;reg key_1 ;reg key_2 ;wire tx_data ;initialbeginsys_clk = 0 ;rst_n = 0 ;key_1 = 1 ;key_2 = 1 ;#10rst_n = 1 ;#10000key_1 = 0 ;endalways #1 sys_clk = ~sys_clk ;TOP TOP_1(. sys_clk (sys_clk) ,. rst_n (rst_n ) ,. key_1 (key_1 ) ,. key_2 (key_2 ) ,. tx_data (tx_data) );endmodule
仿真结果：
TOP：
single_ram_1 :
五、需要注意的一些问题
（1）
（2）
