added LED ring driver code

src/debounce.v

@@ -6,9 +6,10 @@
 `default_nettype none
 
 module debounce (
-  input wire clock, // clock
-  input wire res_n, // active low reset
-  input wire in,    // the input to be debounced
+  input  wire clock, // clock
+  input  wire res_n, // active low reset
+  input  wire in,    // the input to be debounced
+
   output reg out    // debounced output
 );
 

src/led_ring_driver.v

@@ -0,0 +1,133 @@
+/*
+ * Copyright (c) 2024 Fabio Ramirez Stern
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+`default_nettype none
+
+module led_ring_driver (
+  input  wire clock,   // clock (40 Mhz)
+  input  wire res_n,   // active low reset
+  input  wire refresh,
+  input  wire [11:0] led_mask, // one hot mask of which LEDs to turn on and which to keep off
+  input  wire [ 1:0] colour,   // GRB mask
+  input  wire [ 7:0] intensity,  // intensity for LEDs that are 1
+
+  output reg led_dout, // digital output to LEDs
+  output reg busy
+);
+
+  wire skip_calc;
+
+  // input latches
+  reg [11:0] reg_led_mask;
+  reg  [1:0] reg_colour;
+  reg  [7:0] reg_intensity;
+
+  // FSM states
+  reg [3:0] state;
+  localparam IDLE = 2'b00; // idle, wait for refresh
+  localparam CALC = 2'b01; // calc next timings
+  localparam OUTP = 2'b10; // send data to LEDs, retun to CALC
+  localparam TRES = 2'b11; // wait 50us (minimum reset time)
+
+  // timing counters
+  reg  [5:0] tl_counter; // counter for low time (34/18 clk cycles)
+  reg  [5:0] tl_max;
+  reg  [5:0] th_counter; // counter for high time (16/32 clk cycles)
+  reg  [5:0] th_max;
+  reg [11:0] rs_counter; // counter for reset time (4000 clk cycles)
+  reg  [3:0] led_pos;    // led position counter (0..11)
+  reg  [1:0] grb_pos;    // green, red, blue counter (0..2)
+  reg  [3:0] byte_pos;   // grb byte counter (0..7)
+
+
+  always @(posedge clock) begin
+
+    if (!res_n) begin
+      led_dout <= 0;
+      state <= IDLE;
+    end else begin
+    case(state)
+
+      IDLE: begin // wait for refresh to go high, initiate all registers for transmission
+        if (refresh) begin
+          reg_led_mask  <= led_mask;
+          reg_colour    <= colour;
+          reg_intensity <= intensity;
+          rs_counter <= 0;
+          tl_counter <= 0;
+          tl_counter <= 0;
+          tl_counter <= 0;
+          skip_calc <= 0;
+          led_pos  <= 0;
+          grb_pos  <= 0;
+          byte_pos <= 0;
+          state <= CALC;
+        end
+      end // IDLE
+
+      CALC: begin // calculate the timings needed to transmit the next bit, count through bytes of colour, the three colours and the 12 LEDs
+        if(reg_led_mask[led_pos]) begin // if current LED should be on
+          if(reg_colour[grb_pos] && reg_intensity[byte_pos]) begin // if current colour should be on and current intensity bit is 1
+            tl_max <= 32;
+            th_max <= 18;
+          end else begin
+            tl_max <= 16;
+            tl_max <= 34;
+          end
+
+          if (byte_pos < 7) begin // advance to next bit
+            byte_pos = byte_pos + 1;
+          end else begin // end of colour byte, advance to next colour byte
+            if (gbr_pos < 2) begin
+              byte_pos <= 0;
+              grb_pos <= grb_pos + 1;
+            end else begin // end of LED colour word, advance to next LED
+              if (led_pos < 11) begin
+                byte_pos <= 0;
+                grb_pos <= 0;
+                led_pos <= led_pos + 1;
+              end else begin // last bit of last colour of last LED, ie end of transmission, do not go back
+                skip_calc <= 1;
+              end
+            end
+          end
+        end
+
+        state <= OUTP;
+      end // CALC
+
+      OUTP: begin // output one bit according to the WS281B
+        if (tl_counter < tl_max) begin // hold low, count cycles
+          led_dout <= 0;
+          tl_counter = tl_counter + 6'b1;
+        end else begin // hold high, count cycles
+          if(th_counter < th_max) begin
+            led_dout <= 1;
+            th_counter <= th_counter + 6'b1;
+          end else begin
+            if(skip_calc) begin // end of transmission? don't go to CALC, advance to TRES
+              state <= TRES;
+            end else begin
+              state <= CALC;
+            end
+          end
+        end
+      end // OUTP
+
+      TRES: begin // wait for the minimum reset time (t_res), then advance to IDLE
+        led_dout <= 0;
+        if (rs_counter == 11'b111_1101_0000) begin
+          state <= WAIT;
+        end else begin
+          rs_counter <= rs_counter + 11'b1;
+        end
+      end // TRES
+
+      default:;
+    endcase
+    end
+
+  end
+endmodule

src/rotary_decoder.v

@@ -13,10 +13,11 @@ module rotary_decoder (
   * rotary_clk and rotary_dt can be swapped to change direction, their connection should be arbitrary.
   */
 
-  input wire clk, // 40MHz clock
-  input wire res_n, // active low reset
-  input wire rotary_clk, // output labeled clk of the rotary encoder (active low)
-  input wire rotary_dt,  // output labeled dt  of the rotary encoder (active low)
+  input  wire clk, // 40MHz clock
+  input  wire res_n, // active low reset
+  input  wire rotary_clk, // output labeled clk of the rotary encoder (active low)
+  input  wire rotary_dt,  // output labeled dt  of the rotary encoder (active low)
+
   output reg rotation_up,  // goes high for one clock cycle if rotated upwards (clockwise)
   output reg rotation_dn   // goes high for one clock cycle if rotated downwards (counter clockwise)
 );
@@ -71,7 +72,7 @@ module rotary_decoder (
           if (pause_counter == 16'b1001_1100_0011_1111) begin
             state <= WAIT;
           end else begin
-            pause_counter = pause_counter + 16'b1;
+            pause_counter <= pause_counter + 16'b1;
           end
         end // PAUSE