一、 程序说明

FPGA通过串口定时发送数据，每秒发送1字节，数据不断自增
参考小梅哥教程

二、 uart_tx.v

`timescale 1ns / 1psmodule uart_tx(input		wire 				    sclk,input		wire				    rst_n,output		reg	                   uart_tx);parameter  		CLK_FREQ 	    = 50000000;	//时钟频率50M
parameter  		UART_BAUD 	    = 115200;	//时钟频率50M
parameter  		MAX_BIT_COUNT 	= 9;	//时钟频率50M
localparam 		MAX_BAUD_CNT 	= CLK_FREQ / UART_BAUD;//434reg [7:0] write_data;   //发送数据//运行计数器
reg [31:0] run_cnt;	//波特率计数器
always @(posedge sclk or negedge rst_n)
beginif(rst_n == 1'b0)run_cnt <= 32'd0;else if(run_cnt == CLK_FREQ)run_cnt <= 0;elserun_cnt <= run_cnt + 1;
end//波特率计数器
reg [8:0] baud_cnt;	//波特率计数器
reg en_baud_cnt;	//波特率计数器开关
always @(posedge sclk or negedge rst_n)
beginif(rst_n == 1'b0)baud_cnt <= 8'd0;else if(en_baud_cnt == 1'b1) beginif(baud_cnt == MAX_BAUD_CNT)baud_cnt <= 8'd0;elsebaud_cnt <= baud_cnt + 1;endelsebaud_cnt <= baud_cnt;
end//发送位计数器
reg [4:0] bit_cnt = 0;	//波特率计数器
always @(posedge sclk or negedge rst_n)
beginif(rst_n == 1'b0)bit_cnt <= 4'd0;else if(baud_cnt == MAX_BAUD_CNT)beginif(bit_cnt ==  MAX_BIT_COUNT)bit_cnt <= 4'd0;elsebit_cnt <= bit_cnt + 1;endelsebit_cnt <= bit_cnt;
end //位发送逻辑
always @(posedge sclk or negedge rst_n)
beginif(rst_n == 1'b0)uart_tx <= 1'b0;else if(baud_cnt == MAX_BAUD_CNT/2)beginif(bit_cnt ==  0)uart_tx <= 1'b0;else if(bit_cnt == MAX_BIT_COUNT)uart_tx <= 1'b1;elsebegincase(bit_cnt)1:uart_tx <= write_data[0];2:uart_tx <= write_data[1];3:uart_tx <= write_data[2];4:uart_tx <= write_data[3];5:uart_tx <= write_data[4];6:uart_tx <= write_data[5];7:uart_tx <= write_data[6];8:uart_tx <= write_data[7];default:uart_tx <= uart_tx;endcaseend//uart_tx <= write_data[bit_cnt-1];endelseuart_tx <= uart_tx;
endalways @(posedge sclk or negedge rst_n)
beginif(rst_n == 1'b0)en_baud_cnt <= 1'b0;else if(run_cnt == 0) beginen_baud_cnt <= 1'b1;endelse if(bit_cnt ==  MAX_BIT_COUNT && baud_cnt == MAX_BAUD_CNT)en_baud_cnt <= 1'b0;elseen_baud_cnt <= en_baud_cnt;
endalways @(posedge sclk or negedge rst_n)
beginif(rst_n == 1'b0)write_data <= 8'd0;else if(run_cnt == 0)write_data <= write_data + 1;elsewrite_data <= write_data;
endendmodule

三、 运行截图