Add a several cycle "dead zone" to 7-segment decoder segment select lines to more accurately emulate real hardware

1 files changed, 55 insertions, 16 deletions

diff --git a/fpga/serial/common/remote_access.v b/fpga/serial/common/remote_access.v
index b7f0592..6d14ed4 100644
--- a/fpga/serial/common/remote_access.v
+++ b/fpga/serial/common/remote_access.v
@@ -144,12 +144,27 @@ module remote_access(
 	reg [17:0] digit_blanker_3 = 0;
 	reg [17:0] digit_blanker_4 = 0;
 
+	reg [3:0] digit_activity_counter_1 = 0;
+	reg [3:0] digit_activity_counter_2 = 0;
+	reg [3:0] digit_activity_counter_3 = 0;
+	reg [3:0] digit_activity_counter_4 = 0;
+
 	reg [7:0] led_segment_bus_latch;
+	reg [7:0] led_segment_bus_latch_1;
+	reg [7:0] led_segment_bus_latch_2;
+	reg [7:0] led_segment_bus_latch_3;
+	reg [7:0] led_segment_bus_latch_4;
 	reg [3:0] led_digit_select_latch;
+	reg [3:0] led_digit_select_latch_prev;
 	
 	always @(negedge clk_div_by_eight) begin
-		led_segment_bus_latch = led_segment_bus;
-		led_digit_select_latch = led_digit_select;
+		led_segment_bus_latch <= led_segment_bus_latch_4;
+		led_segment_bus_latch_4 <= led_segment_bus_latch_3;
+		led_segment_bus_latch_3 <= led_segment_bus_latch_2;
+		led_segment_bus_latch_2 <= led_segment_bus_latch_1;
+		led_segment_bus_latch_1 <= led_segment_bus;
+		led_digit_select_latch <= led_digit_select;
+		led_digit_select_latch_prev <= led_digit_select_latch;
 
 		if (led_digit_select_latch[0] == 1) begin
 			digit_blanker_1 = digit_blanker_1 + 1;
@@ -167,24 +182,48 @@ module remote_access(
 			digit_blanker_4 = digit_blanker_4 + 1;
 		end
 
-		if (led_digit_select_latch[0] == 0) begin
-			led_display_bytes[0] = led_segment_bus_latch;
-			digit_blanker_1 = 0;
+		if ((led_digit_select_latch[0] == 0) && (led_digit_select_latch_prev[0] == 0)) begin
+			if (digit_activity_counter_1 > 6) begin
+				led_display_bytes[0] = led_segment_bus_latch;
+				digit_blanker_1 = 0;
+			end else begin
+				digit_activity_counter_1 <= digit_activity_counter_1 + 1;
+			end
+		end else begin
+			digit_activity_counter_1 <= 0;
 		end
-		
-		if (led_digit_select_latch[1] == 0) begin
-			led_display_bytes[1] = led_segment_bus_latch;
-			digit_blanker_2 = 0;
+
+		if ((led_digit_select_latch[1] == 0) && (led_digit_select_latch_prev[1] == 0)) begin
+			if (digit_activity_counter_2 > 6) begin
+				led_display_bytes[1] = led_segment_bus_latch;
+				digit_blanker_2 = 0;
+			end else begin
+				digit_activity_counter_2 <= digit_activity_counter_2 + 1;
+			end
+		end else begin
+			digit_activity_counter_2 <= 0;
 		end
 		
-		if (led_digit_select_latch[2] == 0) begin
-			led_display_bytes[2] = led_segment_bus_latch;
-			digit_blanker_3 = 0;
+		if ((led_digit_select_latch[2] == 0) && (led_digit_select_latch_prev[2] == 0)) begin
+			if (digit_activity_counter_3 > 6) begin
+				led_display_bytes[2] = led_segment_bus_latch;
+				digit_blanker_3 = 0;
+			end else begin
+				digit_activity_counter_3 <= digit_activity_counter_3 + 1;
+			end
+		end else begin
+			digit_activity_counter_3 <= 0;
 		end
-		
-		if (led_digit_select_latch[3] == 0) begin
-			led_display_bytes[3] = led_segment_bus_latch;
-			digit_blanker_4 = 0;
+
+		if ((led_digit_select_latch[3] == 0) && (led_digit_select_latch_prev[3] == 0)) begin
+			if (digit_activity_counter_4 > 6) begin
+				led_display_bytes[3] = led_segment_bus_latch;
+				digit_blanker_4 = 0;
+			end else begin
+				digit_activity_counter_4 <= digit_activity_counter_4 + 1;
+			end
+		end else begin
+			digit_activity_counter_4 <= 0;
 		end
 
 		if (digit_blanker_1 > 128000) begin