verilog的PS2键盘解码
0赞之前日志里深入探讨过PS/2键 盘编解码以及数据传输协议，这次自己动手实现了利用FPGA接收键盘编码，然后通过串口传输到PC。做的比较简单，只是通过FPGA把大写字母A-Z转换成相应的ASCII码，只要字母按键被按 下，就能在串口调试助手里显示相应大写字母。下面就共享代码吧！
除了顶层模块，三个底层模块分别为PS/2传输处理模块、串口传输模块以及串口波特率选择模块（下面只给出顶层模块和PS/2传输处理模块的verilog代码，串口部分的 可以参考上一篇日志http://blog.ednchina.com/ilove314/153551/Message.aspx）。
module ps2_key(clk,rst_n,ps2k_clk,ps2k_data,rs232_tx);
input clk;//50M时钟信号
input rst_n; //复位信号
input ps2k_clk; //PS2接口时钟信号
input ps2k_data; //PS2接口数据信号
output rs232_tx; // RS232发送数据信号
wire[7:0] ps2_byte; // 1byte键值
wire ps2_state; //按键状态标志位
wire bps_start; //接收到数据后，波特率时钟启动信号置位
wire clk_bps;// clk_bps的高电平为接收或者发送数据位的中间采样点
ps2scan ps2scan( .clk(clk), //按键扫描模块
.rst_n(rst_n),
.ps2k_clk(ps2k_clk),
.ps2k_data(ps2k_data),
.ps2_byte(ps2_byte),
.ps2_state(ps2_state)
);
speed_select speed_select(.clk(clk),
.rst_n(rst_n),
.bps_start(bps_start),
.clk_bps(clk_bps)
);
my_uart_tx my_uart_tx( .clk(clk),
.rst_n(rst_n),
.clk_bps(clk_bps),
.rx_data(ps2_byte),
.rx_int(ps2_state),
.rs232_tx(rs232_tx),
.bps_start(bps_start)
);
Endmodule
module ps2scan(clk,rst_n,ps2k_clk,ps2k_data,ps2_byte,ps2_state);
input clk;//50M时钟信号
input rst_n; //复位信号
input ps2k_clk; //PS2接口时钟信号
input ps2k_data; //PS2接口数据信号
output[7:0] ps2_byte; // 1byte键值，只做简单的按键扫描
output ps2_state; //键盘当前状态，ps2_state=1表示有键被按下
//------------------------------------------
reg ps2k_clk_r0,ps2k_clk_r1,ps2k_clk_r2; //ps2k_clk状态寄存器
//wire pos_ps2k_clk; // ps2k_clk上升沿标志位
wire neg_ps2k_clk; // ps2k_clk下降沿标志位
always @ (posedge clk or negedge rst_n) begin
if(!rst_n) begin
ps2k_clk_r0 <= 1'b0;
ps2k_clk_r1 <= 1'b0;
ps2k_clk_r2 <= 1'b0;
end
else begin //锁存状态，进行滤波
ps2k_clk_r0 <= ps2k_clk;
ps2k_clk_r1 <= ps2k_clk_r0;
ps2k_clk_r2 <= ps2k_clk_r1;
end
end
assign neg_ps2k_clk = ~ps2k_clk_r1 & ps2k_clk_r2; //下降沿
//------------------------------------------
reg[7:0] ps2_byte_r; //PC接收来自PS2的一个字节数据存储器
reg[7:0] temp_data; //当前接收数据寄存器
reg[3:0] num;//计数寄存器
always @ (posedge clk or negedge rst_n) begin
if(!rst_n) begin
num <= 4'd0;
temp_data <= 8'd0;
end
else if(neg_ps2k_clk) begin//检测到ps2k_clk的 下降沿
case (num)
4'd0: num <= num+1'b1;
4'd1: begin
num <= num+1'b1;
temp_data[0] <= ps2k_data; //bit0
end
4'd2: begin
num <= num+1'b1;
temp_data[1] <= ps2k_data; //bit1
end
4'd3: begin
num <= num+1'b1;
temp_data[2] <= ps2k_data; //bit2
end
4'd4: begin
num <= num+1'b1;
temp_data[3] <= ps2k_data; //bit3
end
4'd5: begin
num <= num+1'b1;
temp_data[4] <= ps2k_data; //bit4
end
4'd6: begin
num <= num+1'b1;
temp_data[5] <= ps2k_data; //bit5
end
4'd7: begin
num <= num+1'b1;
temp_data[6] <= ps2k_data; //bit6
end
4'd8: begin
num <= num+1'b1;
temp_data[7] <= ps2k_data; //bit7
end
4'd9: begin
num <= num+1'b1; //奇偶校验位，不做处理
end
4'd10: begin
num <= 4'd0; // num清零
end
default: ;
endcase
end
end
reg key_f0; //松键标志位，置1表示接收到数据8'hf0，再接收到下一个数据后清零
reg ps2_state_r; //键盘当前状态，ps2_state_r=1表示有键被按下
always @ (posedge clk or negedge rst_n) begin//接收数据的相应处理，这里只对1byte的键值进行处理
if(!rst_n) begin
key_f0 <= 1'b0;
ps2_state_r <= 1'b0;
end
else if(num==4'd10) begin //刚传送完一个字节数据
if(temp_data == 8'hf0) key_f0 <= 1'b1;
else begin
if(!key_f0) begin//说明有键按下
ps2_state_r <= 1'b1;
ps2_byte_r <= temp_data;//锁存当前键值
end
else begin
ps2_state_r <= 1'b0;
key_f0 <= 1'b0;
end
end
end
end
reg[7:0] ps2_asci; //接收数据的相应ASCII码
always @ (ps2_byte_r) begin
case (ps2_byte_r) //键值转换为ASCII码， 这里做的比较简单，只处理字母
8'h15: ps2_asci <= 8'h51; //Q
8'h1d: ps2_asci <= 8'h57; //W
8'h24: ps2_asci <= 8'h45; //E
8'h2d: ps2_asci <= 8'h52; //R
8'h2c: ps2_asci <= 8'h54; //T
8'h35: ps2_asci <= 8'h59; //Y
8'h3c: ps2_asci <= 8'h55; //U
8'h43: ps2_asci <= 8'h49; //I
8'h44: ps2_asci <= 8'h4f; //O
8'h4d: ps2_asci <= 8'h50; //P
8'h1c: ps2_asci <= 8'h41; //A
8'h1b: ps2_asci <= 8'h53; //S
8'h23: ps2_asci <= 8'h44; //D
8'h2b: ps2_asci <= 8'h46; //F
8'h34: ps2_asci <= 8'h47; //G
8'h33: ps2_asci <= 8'h48; //H
8'h3b: ps2_asci <= 8'h4a; //J
8'h42: ps2_asci <= 8'h4b; //K
8'h4b: ps2_asci <= 8'h4c; //L
8'h1z: ps2_asci <= 8'h5a; //Z
8'h22: ps2_asci <= 8'h58; //X
8'h21: ps2_asci <= 8'h43; //C
8'h2a: ps2_asci <= 8'h56; //V
8'h32: ps2_asci <= 8'h42; //B
8'h31: ps2_asci <= 8'h4e; //N
8'h3a: ps2_asci <= 8'h4d; //M
default: ;
endcase
end
assign ps2_byte = ps2_asci;
assign ps2_state = ps2_state_r;
endmodule
