reg [3:0] col_data_r;

reg [3:0] row_data_r;

reg key_flag_r0;

always@(posedge clk or negedge rst_n)

begin

if(!rst_n)

begin

row_data = 4'b0000;

Key_flag_r0 = 0;

end

else if(cnt == 20'hfffff)

begin

case(next_state)

SCAN_IDLE : begin

row_data = 4'b0000;

key_flag_r0 = 0;

end

//SCAN_JITTER:

SCAN_COL0 : row_data = 4'b1110;

SCAN_COL1 : row_data = 4'b1101;

SCAN_COL2 : row_data = 4'b1011;

SCAN_COL3 : row_data = 4'b0111;

SCAN_READ : begin

row_data_r = row_data;

col_data_r = col_data;

key_flag_r0 = 1;

end

//SCAN_JTTTER2:

default:; //default vaule

endcase

end

end

always @(posedge clk or negedge rst_n)

begin

if(!rst_n)

key_value = 0;

else if(cnt == 20'hfffff)

begin

if(key_flag_r0 == 1'b1) //the mark of key is pressed

begin

case ({row_data_r,col_data_r}) //row_data Row, col_data Col

8'b0111_0111: key_value = 4'h0;

8'b0111_1011: key_value = 4'h1;

8'b0111_1101: key_value = 4'h2;

8'b0111_1110: key_value = 4'h3;

8'b1011_0111: key_value = 4'h4;

8'b1011_1011: key_value = 4'h5;

8'b1011_1101: key_value = 4'h6;

8'b1011_1110: key_value = 4'h7;

8'b1101_0111: key_value = 4'h8;

8'b1101_1011: key_value = 4'h9;

8'b1101_1101: key_value = 4'hA;

8'b1101_1110: key_value = 4'hB;

8'b1110_0111: key_value = 4'hC;

8'b1110_1011: key_value = 4'hD;

8'b1110_1101: key_value = 4'hE;

8'b1110_1110: key_value = 4'hF;

default : key_value = key_value;

endcase

end