examples/up5k_rgb/rgb.v

module top(
  output RGB0, RGB1, RGB2
);

wire clk;

SB_HFOSC inthosc (
  .CLKHFPU(1'b1),
  .CLKHFEN(1'b1),
  .CLKHF(clk)
);

localparam  counter_width = 32;

reg [counter_width-1:0] ctr;

always@(posedge clk)
begin
  ctr <= ctr + 1;
end

localparam  pwm_width = 12;

localparam pwm_max = (2**pwm_width) - 1;
localparam pwm_max_div4 = (2**(pwm_width-2)) - 1;


wire [1:0] phase = ctr[counter_width - 1 : counter_width - 2];
wire [pwm_width-1:0] fade = ctr[counter_width - 3 : counter_width - (2 + pwm_width)];
wire [pwm_width-1:0] fade_div4 = ctr[counter_width - 3 : counter_width - (pwm_width)];

wire [pwm_width-1:0] r_val, g_val, b_val;

//  Fade R->G->B->W->
assign r_val = (phase == 0) ? pwm_max_div4 + (3 * fade_div4) :
               (phase == 1) ? pwm_max - fade :
               (phase == 3) ? fade_div4 :
               0;
              
assign g_val = (phase == 0) ? pwm_max_div4 - fade_div4:
               (phase == 1) ? fade :
               (phase == 2) ? pwm_max - fade :
               (phase == 3) ? fade_div4 :
               0;

assign b_val = (phase == 0) ? pwm_max_div4 - fade_div4:
               (phase == 2) ? fade :
               (phase == 3) ? pwm_max - (3 * fade_div4) :
               0;

reg [pwm_width-1:0] pwm_ctr;

reg pwm_r, pwm_g, pwm_b;

always@(posedge clk)
begin
  pwm_ctr <= pwm_ctr + 1;
  pwm_r <= (pwm_ctr < r_val) ? 1'b1 : 1'b0;
  pwm_g <= (pwm_ctr < g_val) ? 1'b1 : 1'b0;
  pwm_b <= (pwm_ctr < b_val) ? 1'b1 : 1'b0;
end

SB_RGBA_DRV RGBA_DRIVER (
  .CURREN(1'b1),
  .RGBLEDEN(1'b1),
  .RGB0PWM(pwm_g),
  .RGB1PWM(pwm_b),
  .RGB2PWM(pwm_r),
  .RGB0(RGB0),
  .RGB1(RGB1),
  .RGB2(RGB2)
);


defparam RGBA_DRIVER.CURRENT_MODE = "0b1";
defparam RGBA_DRIVER.RGB0_CURRENT = "0b000111";
defparam RGBA_DRIVER.RGB1_CURRENT = "0b000111";
defparam RGBA_DRIVER.RGB2_CURRENT = "0b000111";


endmodule