gateware/simple: Demo tweaks

Signed-off-by: David Shah <dave@ds0.me>

gateware/simple/demo.v

@@ -7,10 +7,11 @@ module demo_top(
 	output [11:0] led
 );
 	
-	reg [11:0] ctr_scroll = 1'b1;
+	reg [35:0] ctr_scroll;
+	reg [35:0] ctr_scroll_swapped;
 	reg clk_div = 0;
 	
-	localparam DIV = 21;
+	localparam DIV = 20;
 	reg [DIV-1:0] div_ctr = 0;
 
 	always @(posedge clk_12) begin
@@ -18,17 +19,29 @@ module demo_top(
 
 		if (clk_div) begin
 			if (!(|ctr_scroll))
-				ctr_scroll <= 1'b1;
+				ctr_scroll <= {1'b1, {10{1'b0}}, 1'b1, {13{1'b0}}, 1'b1};
 			else
-				ctr_scroll <= {ctr_scroll[10:0], ctr_scroll[11]};
+				ctr_scroll <= {ctr_scroll[34:24], ctr_scroll[35],
+				               ctr_scroll[22:12], ctr_scroll[23],
+				               ctr_scroll[10:0], ctr_scroll[11]};
 		end
 	end
 
+	integer i, j;
+	always @(posedge clk_12) begin
+		for (i = 0; i < 36; i = i + 6)
+			for (j = 0; j < 6; j = j + 1)
+				if ((i % 12) == 0)
+					ctr_scroll_swapped[i+j] <= ctr_scroll[i+j];
+				else
+					ctr_scroll_swapped[i+j] <= ctr_scroll[i+5-j];
+	end
+
 	led_ctrl led_ctrl_i (
 		.clk(clk_12),
-		.led_in_yr({ctr_scroll[5:0], dip_sw[1:0], btn}),
-		.led_in_bg({dip_sw[7:2], ctr_scroll[11:6]}),
+		.led_in_yr({ctr_scroll_swapped[23:12] | ctr_scroll_swapped[35:24]}),
+		.led_in_bg({ctr_scroll_swapped[11:0] | ctr_scroll_swapped[35:24]}),
 		.led_pin(led)
 	);
 
-endmodule
+endmodule

gateware/simple/led_ctrl.v

@@ -16,6 +16,10 @@ module led_ctrl (
 
 	always @(posedge clk) ctr <= ctr + 1'b1;
 
+	wire pwm_1_4 = ctr[DIV_FACTOR - 1 : DIV_FACTOR - 2] > 2'b10;
+	wire pwm_7_8 = ctr[DIV_FACTOR - 1 : DIV_FACTOR - 3] > 2'b000;
+
+
 	genvar i;
 	wire [11:0] led_o, led_en;
 	generate
@@ -23,14 +27,16 @@ module led_ctrl (
 			/*
 				Only YR asserted : LED at constant 1'b0
 				Both YR & BG asserted : blend colour by connecting LED to divider MSB
+				    NB: bias towards yellow (i<6) or green (i>=6) for better white/orange
 				Only BG asserted : LED at constant 1'b1
 				Neither asserted : LED off (1'bz)
 			*/
 			assign led_o[i] = led_in_yr[i] ?
-								(led_in_bg[i] ? ctr[DIV_FACTOR - 1] : 1'b0) :
+								(led_in_bg[i] ? (i < 6 ? pwm_1_4 : pwm_7_8) : 1'b0) :
 								1'b1;
 			assign led_en[i] = led_in_yr[i] || led_in_bg[i];
 			assign led_pin[i] = led_en[i] ? led_o[i] : 1'bz;	
+			//BB bb_i (.I(led_o[i]), .T(~led_en[i]), .B(led_pin[i]));
 		end
 	endgenerate