ps2shortkey.v

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`timescale 1ns / 1ps
//////////////////////////////////////////////////////////////////////////////////
// Company: 
// Engineer: 
// 
// Create Date:    20:28:42 08/01/2007 
// Design Name: 
// Module Name:    ps2shortkey 
// Project Name: 
// Target Devices: 
// Tool versions: 
// Description: 
//
// Dependencies: 
//
// Revision: 
// Revision 0.01 - File Created
// Additional Comments: 
//
//////////////////////////////////////////////////////////////////////////////////
`define LEFT_SHIFT   8'h12//16'h12????
`define RIGHT_SHIFT  8'h59
`define RELEASE_CODE	8'hf0
//`define EXTEND_CODE

module ps2shortkey(clk, rst_n, ps2c, ps2d, dout, ready);
    input clk;
    input rst_n;
    input ps2c;
    input ps2d;
    output [7:0] dout;
    output ready;
reg ready;
reg ps2c_delay;
//reg ps2d_delay;
wire ps2clk_l;
//wire ps2data;
wire clk10u;

wire release_key;
wire shift_on;
reg pull_down;

reg enstart;
reg [8:0] cnt10u;//84
reg [4 : 0] scan_count;
always @ (posedge clk or negedge rst_n)
if(!rst_n) cnt10u <= 0 ;
else cnt10u <= cnt10u + 1;


assign clk10u = (cnt10u == 9'b111111111) ;
//wire clk10u_up ;
//assign clk10u= (cnt10u == 5'b11111); 
always @ (posedge clk)
if(clk10u)
	ps2c_delay <= ps2c;
	
reg [15:0] delay1ms; //15

//debounce delay (prevent error fall)
always @ (posedge clk or negedge rst_n)
if(!rst_n) delay1ms <= 0 ;
else if(delay1ms == 16'hffff) delay1ms <=0;
else if(enstart) delay1ms <= delay1ms + 1;



always @ (posedge clk)
if (!rst_n) enstart <= 0 ;
else if(delay1ms == 16'hffff) enstart <= 0 ;
else if(ps2clk_l&&(scan_count == 0)) enstart <= 1;

assign ps2clk_l =~ps2c&&(ps2c_delay); //if ps2c down >>>ps2clk_1 set up 


always @ (posedge clk or negedge rst_n)
if(!rst_n)
		scan_count <= 0 ;
else if ((scan_count == 11)||(~enstart)) scan_count <= 0 ;
else if (ps2clk_l&&clk10u) scan_count <= scan_count + 1;

reg [10 :0 ] rxbuf ;

/*reg [3:0] ready_delay; 
always @ (posedge clk or negedge rst_n)
if(!rst_n) ready_delay <= 0 ;
else if (scan_count == 11) ready_delay <= 0 ;
else if ((scan_count == 10) && ready_delay <= 4'b1110)
			ready_delay <= ready_delay + 1 ;*/
	

always @ (posedge clk or negedge rst_n)
if(!rst_n) rxbuf<=0 ;
//
else if (ps2clk_l)
		rxbuf[scan_count]<=ps2d;

reg [7:0] keydata;
reg [8:0] q;
always @ (posedge clk or negedge rst_n)
if (!rst_n) q <= 0 ;
else q <= rxbuf [9:1] ;

always @ (posedge clk or negedge rst_n)
if(!rst_n) ready <= 0 ;
else if( 
	(q[0]^q[1]^q[2]^q[3]^q[4]^q[5]^q[6]^q[7]==(~q[8]))&&
		(scan_count == 10)  &&
//		 ~ready_delay[3]&&
			ps2clk_l  &&
			(~shift_on) &&
		 pull_down)

		ready <= 1 ;

else ready <= 0 ;
reg rx_shift_on;
assign release_key =( q[7:0] == `RELEASE_CODE)  ;
assign shift_on =((q[7:0] ==`LEFT_SHIFT)||(q[7:0] ==`RIGHT_SHIFT));

always @ (posedge clk or negedge rst_n)
if(!rst_n) rx_shift_on <= 0 ;

else if ((~pull_down)&&(shift_on)) rx_shift_on <= 0;
//else if ()
else if (shift_on&&(scan_count == 9)) rx_shift_on <= 1;

always @ (posedge clk or negedge rst_n)
if(!rst_n) pull_down <= 1;//1
else if (release_key) pull_down <= 0 ;
else 
	begin
	if((scan_count == 11)&& (~release_key))
	pull_down <= 1'b1 ;
	end

always @ (posedge clk or negedge rst_n)
begin
if(!rst_n) keydata <= 0;
else if(pull_down && (~shift_on))
	begin 
	if ((scan_count == 10))
	keydata <= q[7:0];
	
	end

end

//assign ready = (scan_count == 10);
wire [11:0] keycode;

reg [7:0] ascii;
//assign rx_shift_on = 0 ;
assign keycode = {3'b0,rx_shift_on,keydata};
always @(keycode)
begin
  casez (keycode)
	 // SHORT KEY
    12'h079 : ascii <= 8'h2b;  // +
    12'h07c : ascii <= 8'h2a;  // *
    12'h070 : ascii <= 8'h30;  // 0
    12'h069 : ascii <= 8'h31;  // 1
    12'h072 : ascii <= 8'h32;  // 2
    12'h07a : ascii <= 8'h33;  // 3
    12'h06b : ascii <= 8'h34;  // 4
    12'h073 : ascii <= 8'h35;  // 5
    12'h074 : ascii <= 8'h36;  // 6
    12'h06c : ascii <= 8'h37;  // 7
    12'h075 : ascii <= 8'h38;  // 8
    12'h07d : ascii <= 8'h39;  // 9
    12'h07b : ascii <= 8'h2d;  // -
    12'h04a : ascii <= 8'h2f;  // /
	 12'h066 : ascii <= 8'h08;  // Backspace ("backspace" key)
	 12'h071 : ascii <= 8'h02;// (Delete OR DEL on numeric keypad)
	 12'h077 : ascii <= 8'h04;// numeric keypad)
    12'h05a : ascii <= 8'h01;  // Carriage return ("enter" key)
	 //short key
	 
    default : ascii <= 8'h2e;  // '.' used for unlisted characters.
	   endcase
end
assign dout = ascii ;
endmodule