6502.org

Code: Select all

module VDACif( input clk108,
					input hstart,
					input vstart,					
					input hblank,
					input vblank,
					input VSYNCout,
					output reg [4:0] Red_data = 0,
					output reg [5:0] Green_data = 0,
					output reg [4:0] Blue_data = 0,
					output reg DACBLANKn = 1
					);

reg countflag;
reg [9:0] X = 0;
reg [8:0] Y = 0;

parameter
Xmax = 640,
Ymax = 480;

always @(posedge clk108)
      if ( hstart )
         countflag <= 1;									//countflag active in display area
      else if ( hblank )
         countflag <= 0;
			
always @(posedge clk108)
	if ( countflag )
		X <= X + 1;												//count inside the border
		else 
			X <= 0;
			
always @(posedge clk108)
	if ( X == Xmax )		
		Y <= Y + 1;
	 else if ( Y == Ymax )
		Y <= 0;
			
always @(posedge clk108)								//outgoing data to videoDAC	
	if ( countflag & (( X == 0 & Y == 0 ) | ( X == 639 & Y == 479 ))) begin
		Red_data <= 0;
		Green_data <= 6'b111111;
		Blue_data <= 0;									//Priority 1, plot green pixel at Min & Max corners
	end
		else if ( vblank & VSYNCout ) begin			
			Red_data <= 0;
			Green_data <= 0;
			Blue_data <= 0;								//Priority 2, send black during vertical retrace
		end
		else if ( !countflag ) begin
			Red_data <= 0;
			Green_data <= 0;
			Blue_data <= 5'b11111;						//Priority 3, blue border
		end
		else if ( X[0] ) begin				
			Red_data <= 5'b11111;		
			Green_data <= 0;
			Blue_data <= 0;								//Priority 4, odd pixels red
		end
			else begin				
				Red_data <= 0;
				Green_data <= 0;
				Blue_data <= 5'b11111;					// even pixels blue
			end
	
endmodule

Code: Select all

RAMB16_S18_S18 line1X (
	.CLKA(clk108),
	.ADDRA(Z),
	.DIPA(2'b0),		// write 0
	.DIA(0),
	.DOA(X1),		
	.ENA(countflag),		// only in visible area
	.WEA(1'b0),		// always read
	.SSRA(1'b0),

	.CLKB(clk108),
	.ADDRB(Z),
	.DIPB(2'b0),
	.DIB(Xdata),
	.ENB(countflag),
	.SSRB(1'b0),	
	.WEB(countflag)		//always write
	);
	
	RAMB16_S18_S18 line1Y (
	.CLKA(clk108),
	.ADDRA(Z),
	.DIPA(2'b0),		// write 0
	.DIA(0),
	.DOA(Y1),		
	.ENA(countflag),		// only in visible area
	.WEA(1'b0),		// always read
	.SSRA(1'b0),

	.CLKB(clk108),
	.ADDRB(Z),
	.DIPB(2'b0),
	.DIB(Ydata),
	.ENB(countflag),
	.SSRB(1'b0),	
	.WEB(countflag)		//always write
	);

Code: Select all

always @(posedge clk108)
	if ( Z == Zmax )
		Z <= 0;
		else if ( countflag )
			Z <= Z + 1;