keypress_det.v

键盘去抖动CPLD设计经过验证,可以直接用数码管显示,同时也希望大家给于新想法

//----------------------------------------
//Detect Keyboard pression 
//Filename : keypress_det
//----------------------------------------
module keypress_det
	(
		SCAN_CODE,
		ROW,
		COLUMN,
		PRESSIN,
		PRESSOUT,
		REAL_code
	);


	input	[1:0]	SCAN_CODE;
	input	[3:0]	ROW;
	input	PRESSIN;

	output	[3:0]	COLUMN;
	output	[3:0]	REAL_code;
	output	PRESSOUT;

	reg	[3:0]	COLUMN;
	reg	[3:0]	REAL_code;
	reg	[3:0]	ROWin;


always @ (SCAN_CODE or ROW)
begin 
	case (SCAN_CODE)
	    2'b00 : COLUMN = 4'b1110;
	    2'b01 : COLUMN = 4'b1101;
	    2'b10 : COLUMN = 4'b1011;
	    2'b11 : COLUMN = 4'b0111;
		default : COLUMN = 4'b1111;
	endcase

	ROWin = ROW;

	if (PRESSIN ==1'b1)
		begin
			if (ROWin[0]==1'b0)
				REAL_code = {SCAN_CODE+2'b11, 2'b00};
					if (ROWin[1]==1'b0)
						REAL_code = {SCAN_CODE+2'b11, 2'b01};
				if (ROWin[2]==1'b0)
						REAL_code = {SCAN_CODE+2'b11, 2'b10};
			if (ROWin[3]==1'b0)
				REAL_code = {SCAN_CODE+2'b11, 2'b11};
		end
end

assign PRESSOUT = &ROWin;

endmodule