mirror of
https://github.com/sehugg/8bitworkshop.git
synced 2024-12-22 12:30:01 +00:00
43 lines
851 B
Verilog
43 lines
851 B
Verilog
|
|
`include "hvsync_generator.v"
|
|
`include "lfsr.v"
|
|
|
|
/*
|
|
Scrolling starfield generator using a period (2^16-1) LFSR.
|
|
*/
|
|
|
|
module starfield_top(clk, reset, hsync, vsync, rgb);
|
|
|
|
input clk, reset;
|
|
output hsync, vsync;
|
|
output [2:0] rgb;
|
|
wire display_on;
|
|
wire [8:0] hpos;
|
|
wire [8:0] vpos;
|
|
wire [15:0] lfsr;
|
|
|
|
hvsync_generator hvsync_gen(
|
|
.clk(clk),
|
|
.reset(reset),
|
|
.hsync(hsync),
|
|
.vsync(vsync),
|
|
.display_on(display_on),
|
|
.hpos(hpos),
|
|
.vpos(vpos)
|
|
);
|
|
|
|
// enable LFSR only in 256x256 area
|
|
wire star_enable = !hpos[8] & !vpos[8];
|
|
|
|
// LFSR with period = 2^16-1 = 256*256-1
|
|
LFSR #(16'b1000000001011,0) lfsr_gen(
|
|
.clk(clk),
|
|
.reset(reset),
|
|
.enable(star_enable),
|
|
.lfsr(lfsr));
|
|
|
|
wire star_on = &lfsr[15:9]; // all 7 bits must be set
|
|
assign rgb = display_on && star_on ? lfsr[2:0] : 0;
|
|
|
|
endmodule
|